CN115769502B - Transceiver system for near field communication, near field reader system and frequency division coordination automatic power control method - Google Patents

Abstract

Techniques for frequency division coordination for automatic power control (automatic power control, APC) in transceivers of near field readers are described. Such frequency-division-coordinated APC (FDC-APC) can enable continuous APC updates concurrent with communication frames to achieve field strength specifications without typically degrading communication reliability. For example, the transceiver implements an FDC-APC loop that receives a detuned signal from a signal received and/or transmitted over the near-field communication link, generates an error signal by comparing the detuned signal to a reference detuned level, and updates a power control signal according to an update frequency (e.g., corresponding to an APC loop bandwidth) that is at least a function of a filter frequency distribution and out-of-band with respect to a modulation band. The modulation signal may be transmitted over the near field communication link according to a variable power setting controlled by the power control signal.

Description

Transceiver system for near field communication, near field reader/writer system and frequency division coordinated automatic power control method

Cross-references to related applications

This patent document claims priority to and the benefit of U.S. Patent Application No. 17/110,295, filed on December 3, 2020, entitled “FREQUENCY-DIVISION-COORDINATED AUTOMATIC POWER CONTROL FOR NEAR-FIELD COMMUNICATION”. The entire contents of the above patent application are incorporated by reference as part of this patent disclosure.

Technical Field

The present invention generally relates to near field communications and more particularly to continuous field control for uninterrupted near field communications, for example, for uninterrupted dynamic control of near field wireless communications between a reader and a passive or simulated passive device.

Background technique

Various types of short-range radiofrequency (RF) communications, including Near-Field Communications (NFC), have become ubiquitous in a wide range of applications, such as contactless access cards, contactless payment cards, contactless interfaces between devices and peripherals, etc. A typical NFC system uses inductive coupling to achieve contactless data exchange within a short range (e.g., about 1.5 inches) between at least two elements: a reader or other "poller" (generally referred to as a reader in this article); and a tag, card or other "listener" (generally referred to as a tag in this article). Many NFC applications support passive devices, where the device includes one or more integrated chips and an integrated antenna, but no battery. Other NFC applications support the so-called "card emulation" or "CE" mode, in which an active device (e.g., a smartphone) can emulate a passive card or tag. During operation, the reader can send command transmissions by modulating an RF carrier that electrically induces current in the device's antenna. The electrically induced signal can be collected by the device for power, timing, receiving commands, etc., and the device can automatically respond by modulating the RF carrier according to the device data. The reader can detect and process the response to recover the device data.

Such NFC communications involve forming a near-field wireless communication link through mutual inductance and/or magnetic coupling between the reader and device antennas. This coupling effectively inserts the tag as an additional load into the reader antenna circuit, and the size of this additional load varies with the distance between the tag and the reader. Typically, when the reader is not loaded by any close-range NFC device, the reader is tuned to operate near a resonant operating frequency (e.g., 13.65 MHz for some NFC communications). However, when an NFC device is close to the reader, the change in load on the reader antenna causes its resonant frequency to detune away from the tuned operating frequency. To compensate for this detuning, some readers can detect the detuning and adjust the transmit power accordingly. However, this traditional method of compensation may tend to degrade communication quality and/or potentially damage the circuitry of the device being read.

Summary of the invention

Embodiments provide circuits, devices, and methods for frequency division coordination of automatic power control (APC) in a transceiver for a near-field reader/writer. Such frequency-division-coordinated APC (FDC-APC) can implement continuous APC updates concurrently with communication frames to achieve field strength specifications without generally degrading communication reliability. For example, the transceiver implements an FDC-APC loop that receives a detuning signal from a signal received and/or transmitted via a near-field communication link, generates an error signal by comparing the detuning signal with a reference detuning level, and updates a power control signal according to an update frequency (e.g., corresponding to an APC loop bandwidth) that is at least a function of a filter frequency distribution and is out-of-band relative to a modulation band. A modulated signal can be transmitted over a near-field communication link according to a variable power setting controlled by the power control signal.

According to one set of embodiments, a transceiver system for near field communication is provided. The transceiver system includes: a receiver for receiving a response signal through a near field communication link; a transmitter for transmitting a command signal through the near field communication link according to a power control signal, the command signal being generated by modulating a carrier within a modulation frequency band; and a frequency division coordinator coupled to the transmitter. The frequency division coordinator is used to: receive a detuning signal from the receiver and/or the variable power transmitter; generate an error signal by comparing the detuning signal with a reference detuning level; and generate the power control signal by filtering the error signal according to a filter frequency distribution, so that the power control signal is dynamically updated according to an update frequency, the update frequency being a function of at least the filter frequency distribution and being out-of-band relative to the modulation frequency band.

According to some such embodiments, a near-field reader system includes a reader antenna and a reader passive network coupled to the transceiver system. In such embodiments, the reader antenna and the reader passive network are used to: establish the near-field link through inductive coupling with the tag when the proximity of the tag to the near-field reader system is within a threshold distance, the establishment causing a variable load to the near-field reader system through the tag based at least on the proximity; receive the response signal through the near-field communication link and transmit the response information to the receiver; and receive the command signal from the transmitter and transmit the command signal through the near-field communication link.

According to another set of embodiments, a method for frequency division coordinated automatic power control of a near field transceiver is provided. The method includes: updating a power control signal by iteration according to an update frequency, the update frequency being a function of at least one filter frequency distribution and being out-of-band relative to a modulation frequency band: generating a detuning signal during communication of a signal by the near field transceiver through a near field communication link, such that the detuning signal corresponds to a current field strength of the near field communication link, the current field strength varying in response to a dynamic load on the near field transceiver by a tag inductively coupled through the near field communication link; generating an error signal by comparing the detuning signal with a reference detuning level; and generating the power control signal by filtering the error signal according to the filter frequency distribution. The signal communication by the near field transceiver through the near field communication link is according to modulation of a carrier signal in the modulation frequency band. The signal communication includes transmitting a command signal by the near field transceiver through the near field communication link according to the power control signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitute a part of this document, illustrate embodiments of the present disclosure. The drawings, together with the description, serve to explain the principles of the present invention.

FIG. 1 shows an illustrative Near-Field Communications (NFC) transaction environment as a context for various embodiments described herein.

FIG. 2 shows a schematic NFC communication environment with an example of a reader/writer implementing conventional automatic power control (APC) according to some prior art embodiments.

FIG. 3 is a schematic graph showing potential damage to an amplitude-modulated (AM) data frame caused by a conventional APC method.

FIG. 4 illustrates an exemplary NFC communication environment 400 with a reader implementing frequency division coordination (APC) according to various embodiments described herein.

FIG. 5 illustrates another exemplary NFC communication environment with a reader implementing frequency division coordination (APC) based on transmitter-side sensing according to various embodiments described herein.

6 and 7 include a number of graphs illustrating the effect of such frequency division coordination in the context of APC for a near field reader.

FIG8 illustrates an exemplary reader/writer for implementing additional frequency division coordination (APC) techniques based on transmitter-side sensing according to various embodiments described herein.

FIG. 9 shows an exemplary NFC communication environment with additional power control feedback according to various embodiments described herein.

FIG. 10 shows an exemplary NFC communication environment according to various embodiments described herein.

FIG. 11 shows a flow chart of an exemplary method for frequency division coordinated automatic power control of a near-field transceiver according to various embodiments described herein.

In the accompanying drawings, similar components and/or features may have the same reference number. In addition, individual components of the same type may be distinguished by following the reference number with a second reference number that is used to distinguish between similar components. If only the first reference number is used in the specification, the description may apply to any of the similar components having the same first reference number without regard to the second reference number.

Detailed ways

In the following description, many specific details are provided to thoroughly understand the present invention. However, it will be appreciated by those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, for the purpose of brevity, features and techniques known in the art are not described.

Various types of short-range radiofrequency (RF) communications are becoming ubiquitous in a wide range of applications. For example, passive, contactless data devices are being used to authorize access to secure facilities, conduct electronic payment transactions at points of sale, withdraw cash at ATMs, quickly register and/or connect peripheral devices (e.g., headphones, printers, drives, etc.) to electronic devices, etc. Near-Field Communications (NFC) is an RF communication technology that uses inductive coupling between devices to enable contactless data exchange between devices over a short range (e.g., about 1.5 inches). A typical NFC system includes at least two elements: a reader or other "poller" (generally referred to as a "reader" in this article); and a tag, card or other "listener" (generally referred to as a "tag" in this article). Although terms such as "reader" and "tag" are used herein, it should be understood that certain novel embodiments described herein can generally be applied to any device that communicates using automatic power control over a mutual inductive link, etc.

FIG. 1 shows a schematic near-field communication (NFC) transaction environment 100 as a context for various embodiments described herein. As shown, the NFC transaction environment includes a reader 110 and a tag 120. In some embodiments, the tag 120 is a passive device, such as a passive contactless smart card, a passive tag, etc. In such an embodiment, the passive tag 120 typically includes one or more integrated chips and an integrated antenna, but no battery. In other embodiments, the tag 120 is implemented by an active device, such as a smartphone, a wearable device (e.g., a smart watch or a fitness tracker), etc. In some such embodiments, the active device is used to support the so-called "card emulation" or "CE" mode, in which the active device emulates a passive card or tag. For example, in CE mode, even in low-power standby mode, the active device can act as an emulated passive tag to perform near-field wireless communication with the reader, or perform near-field wireless communication with minimal power consumption. The reader 110 can be implemented in any suitable device, such as an electronic lock, an access control system, a point-of-sale terminal, an automated teller machine, etc.

A typical NFC transaction may involve a reader 110 reading a tag 120 via an NFC link 130. The reader 110 uses a reader transceiver block ("Tx/Rx") 116, a reader passive network 114, and a reader antenna 112 to broadcast a "command" signal 132 on a modulated RF carrier. For example, the reader 110 modulates the RF carrier using amplitude shift keying (ASK), on-off keying (OOK), or other suitable techniques (e.g., at 13.56 MHz). The tag 120 receives the command signal 132 via the NFC link 130 using the tag antenna 122, the tag passive network 124, and the tag transceiver block 126. The command signal 132 electrically induces a current in the tag antenna 122. The electrically induced energy from the command signal 132 may be collected and conditioned by the tag 120 to generate power for circuits, derive clock information, interpret commands from the reader 110, and the like. The active circuit of the tag 120 may automatically respond by sending a response signal 134 from the tag 120 to the reader 110 through the NFC link 130. For example, the tag 120 may generate the response signal 134 by modulating the load (e.g., by active load modulation or passive load modulation) according to data stored on the tag or in a memory accessible to the tag. The reader may detect and process the response signal 134 to recover the transmitted data.

When the reader 110 interrogates the tag 120 to exchange data through the NFC link 130, both the reader antenna 112 and the tag antenna 122 are primarily inductive. When the tag 120 is within a certain distance of the reader 110 (or the reader 110 to the tag 120), the NFC link 130 is formed by mutual inductance and/or magnetic coupling between the reader antenna 112 and the tag antenna 122. The NFC link 130 effectively extends the circuit of the reader antenna 112 to include the tag 120. Therefore, the tag 120 effectively becomes an additional load on the transmitter of the reader 110 through mutual coupling. The size of this additional load varies with the distance between the tag 120 and the reader 110. For example, when the tag 120 is close to the reader 100, the effective load on the reader antenna 112 increases.

When the reader 110 is not loaded by any tag 120 (for example, when no tag 120 is close to the reader 100), the reader 110 can be calibrated to a "tuned" configuration. In such a configuration, the components of the reader transceiver block 116, the reader passive network 114, and the reader antenna 112 can be tuned to resonate around the operating carrier frequency (for example, 13.65 MHz for some NFC communications). When the tag 120 approaches the reader 110, the load of the tag 120 changes the impedance of the reader antenna 112, which causes the resonant frequency of the reader 110 circuit to detune and deviate from the tuned operating frequency. As used herein, such "detuning" can generally refer to the overall process and effect of the tag 120 approaching the reader 110, the increase in the load of the reader antenna 112 caused by this, the deviation of the resonant frequency of the reader antenna 112 and related components caused by this, etc.

Such detuning may prevent effective communication on the NFC link 130. For example, output field strength is one of the important requirements that the reader 110 must meet in order to comply with different NFC standards. The field strength generated by the reader 110 must comply with the upper and lower limits of the field strength within a specific operating volume around the reader 110. The upper and lower limits of the field strength and the operating volume are independently specified by each NFC standard. Although the field is initially generated by the reader 110, the field strength over the entire operating volume (i.e., the effective volume in which communication occurs between the reader 110 and the tag 120) does not depend entirely on the reader 110. It also depends on the structure of the tag 110 and the position in the operating volume. As described above, this is at least due to the proximity loading of the tag 120 to the reader 110 when the tag 120 is close to the reader 110 within the operating volume. In particular, the movement of the tag 120 relative to the reader 110 affects the detuning, which manifests as a change in the field strength distribution over the entire operating volume. Therefore, in order to meet field strength specifications (e.g., according to the NFC standard), a conventional reader 110 may be used to sense proximity-based detuning and accordingly dynamically update the transmit power of the transmitter of the reader 110. This sense-update loop is generally referred to as automatic power control (APC) or dynamic power control (DPC).

FIG2 shows a schematic NFC communication environment 200 with an example of a reader 110 implementing a conventional APC according to some prior art embodiments. As described with reference to FIG1 , the reader 110 and the tag 120 communicate via an NFC link 130. For example, the reader 110 and the tag 120 are close enough to be electrically inductively coupled. The tag 120 includes a tag antenna 122, a tag passive network 124, and a tag transceiver block 126. The reader 110 has a reader antenna 112, a reader passive network 114, and a reader transceiver block 116. The reader transceiver block 116 is used to implement a conventional APC loop 250, which can sense the detuning at the reader 110 and can automatically control the power of the variable power transmitter 240 accordingly.

The reader 110 receives signals, such as response signals 134, from the tag 120 via the NFC link 130. These signals are received by the receiver (Rx) 210 and fed to the receiver (Rx) 210 as processed response signals 205. The receiver 210 can use the processed response signals 205 to extract the data sent from the tag 120 and generate one or more detuning signals 215 to indicate the detuning condition caused by the tag 120 (e.g., based on the configuration and position of the tag 120 relative to the reader 110). The receiver 210 can also send the extracted data signals to the controller 220. The detuning signals 215 are fed into a set of stored APC look-up tables (LUTs) 230, which can map the detuning condition indicated by the detuning signals 215 to the corresponding pre-calibrated power settings, the values of the new power settings for the variable power transmitter 240. The power setting data from the APC LUTs 230 is also fed to the controller 220. For example, the controller 220 can be implemented using a central processing unit CPU, an application-specific integrated circuit (ASIC), an application-specific instruction-set processor (ASIP), a digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a controller, a microcontroller unit, a reduced instruction set (RISC) processor, a complex instruction set processor (CISC), a microprocessor, etc., or any combination thereof.

The controller can generate signals for the variable power transmitter 240 using data received from the receiver 210 and from the APC LUTs 230, for example, the controller 220 generates a power control signal 225 to control the power level of the variable power transmitter 240, and a data signal 227 (e.g., including baseband data and other data for transmission to the tag 120 via the NFC link 130). The variable power transmitter 240 generates a command signal 245 (e.g., including the command signal 132) based on the received data signal 227 and the power control signal 225. The command signal 244 can be passed to the reader passive network 114 and the reader antenna 112 to transmit at the adjusted power level on the NFC link 130.

While this conventional approach may work wonders, it has certain limitations. One of which is that in this implementation, the new power setting is not directly applied to the variable power transmitter 240. For example, relatively fast and/or large updates to the transmitter power may be perceived as amplitude modulation (AM) on the reader 110 side and/or the tag 120 side, which may interfere with the actual AM data frames exchanged between the two sides and ultimately interrupt communication between the tag 120 and the reader 110.

An example of these limitations can be seen by briefly referring to FIG. 3 . FIG. 3 shows a schematic graph of potential damage to an AM data frame caused by a conventional APC approach. For example, a schematic unmodulated RF carrier signal 305 and a schematic modulation signal 315 (e.g., representing a bit stream) are fed to an amplitude modulation block 310. The amplitude modulation block 310 modulates the unmodulated RF signal 305 according to the modulation signal 312 to generate a modulated carrier signal 320. As can be seen, the modulated carrier signal 320 has a modulation depth 325. At a certain time 345, APC occurs in response to a detected change in field strength. This can be seen by a reduction in the power level represented by the power control signal 225. For example, when the tag 120 is close to the reader 110, it is desirable to reduce the transmit power at the reader 120 to avoid transmitting too much power to the tag 120 and potentially damaging the tag 120 circuit. The schematic conventional APC block 330 is shown as adjusting the transmit power of the modulated carrier signal 320 according to the power control signal 225 to generate a power-adjusted modulated carrier signal 340. It can be seen that the power adjustment effectively reduces the high level of the power adjusted modulated carrier signal 340 to a level close to its previous low level, so that the power adjusted high data bits can basically appear as low data bits after the power adjustment.

Many conventional implementations recognize and address this problem. For example, returning to FIG. 2 , the updated transmitter power settings calculated by the APC LUTs 230 are not fed directly to the variable power transmitter 240. Instead, these power settings are fed to the controller 220, which can evaluate the state and timing of the communication between the reader 110 and the tag 120 using information from the transmitted and received data signals (e.g., the transmit and receive windows). Based on such state and timing information, the controller 220 can determine the appropriate time when it can update the transmitter power settings without interrupting NFC communications. Typically, the controller 220 waits for a specific time slot between communication frames to apply any new power settings, so that these power settings only take effect when neither the reader 110 nor the tag 120 is listening to each other.

While this approach is effective in some applications, it still has some limitations. For example, this time-division coordination can be effective when there are short communication frames and slow-moving tags 120. However, some communication frames have relatively long durations compared to the speed of movement of the tag 120 within the operating volume, and the rate of change of the detuned condition may be too slow to meet the field strength specification. For example, if the tag 120 changes position significantly during the communication frame duration, but the transmit power setting remains fixed throughout the frame duration, the field strength specification may be violated and/or damage may be caused to the tag 120. Therefore, many conventional implementations include protection measures. One such protection measure is, for example, if too much time has passed since the last update, or the detuned signal 215 indicates that the detected field strength has changed too much, then forcing an intermediate frame APC update. Another such protection measure is to impose a current limit on the variable power transmitter 240 so that if the power level becomes too high, the variable power transmitter 24 automatically stops transmitting. In either case, in the case of relatively long communication frames, the probability of forced APC updates and/or forced current gating occurring may be high. Either situation may interrupt the communication between the tag 120 and the reader/writer 110, causing the NFC communication to become less reliable.

The embodiments described herein include some new APC methods. For example, traditional methods tend to use time division coordination, which seeks to coordinate the timing of APC updates with the communication frame timing. The embodiments described herein may use frequency division coordination in the APC loop, which may allow APC updates to be performed simultaneously with the communication frame. For example, an embodiment may continuously run the APC loop to update the transmitter power in a substantially continuous manner, but the update frequency is very low. The update frequency can be selected to be significantly lower than the modulation frequency (e.g., bit rate) of the AM signal communicated between the reader 110 and the tag 120, thereby ensuring that the power update is not perceived as data. This frequency division coordination can achieve field strength specifications while avoiding the degradation of communication reliability common in traditional methods.

Various embodiments of a transceiver system for near field communication are described herein. The transceiver system includes at least a receiver, a transmitter, and a frequency division APC coordinator. The receiver can typically receive a response signal via a near field communication link. The transmitter can typically transmit a command signal via a near field communication link based on a power control signal. The command signal and/or the response signal are generated by modulating a carrier within a modulation band. An embodiment of the frequency division APC coordinator receives a detuning signal from a receiver and/or from a variable power transmitter, generates an error signal by comparing the detuning signal with a reference detuning level, and updates the power control signal according to an update frequency (e.g., corresponding to the APC loop bandwidth), which is a function of at least one filter frequency distribution and is out-of-band relative to the modulation band. Figures 4–10 describe various implementations of a near field reader/writer system including components that implement the features of a frequency division APC coordinator.

FIG4 shows an illustrative NFC communication environment 400 with a reader 110 implementing frequency division coordinated APC according to various embodiments described herein. As described with reference to FIG1 , the reader 110 and the tag 120 communicate via an NFC link 130. For example, the reader 110 and the tag 120 are close enough to be electrically inductively coupled. The tag 120 includes a tag antenna 122, a tag passive network 124, and a tag transceiver block 126. The reader 110 has a reader antenna 112, a reader passive network 114, and a plurality of other components that constitute a reader transceiver block (not explicitly labeled). The reader transceiver block may include at least one receiver 210, a controller 220, a reference signal generator 410, an error amplifier 420, a loop filter 430, and a variable power transmitter 240. The reference signal generator 410, the error amplifier 430, and the loop filter 430 may be considered to implement a frequency division APC coordinator. The reader 110 receives signals such as response signals 134 from the tag 120 via the NFC link 130. These signals are received by the receiver 210 and fed to the receiver 210 as processed response signals 205. The receiver 210 can use the processed response signals 205 to extract the data sent from the tag 120 and generate one or more detuning signals 215 to indicate the detuning condition caused by the tag 120 (e.g., based on the structure of the tag 120 and the position relative to the reader 110). As described with reference to FIG. 2, the receiver 210 can also send the extracted data signal to the controller 220, and the controller 220 can generate a data signal 227 (e.g., including baseband data and other data) to be transmitted to the tag 120 via the NFC link 130.

At least some of the reader transceiver block components are used to implement a frequency division coordinated APC loop 450, which can sense the detuning at the reader 110 and can automatically control the power to the variable power transmitter 240 accordingly. For example, the APC loop 450 shown does not include the controller 220. An embodiment of the reference signal generator 410 generates a reference signal 415. In some implementations, the reference signal generator 410 is programmed to generate a reference signal 415 suitable for the reader 110 and the target standard (e.g., the NFC standard). The reference signal 415 can be generated as a signal of the same type as the detuning signal 215 (e.g., which can be compared by the detuning circuit 215). For example, the reference signal 415 (and the detuning signal 215) can be represented as one or more voltage levels, current levels, power levels, digital words, etc.

In some embodiments, the reference signal 415 is a reference detuning signal based on a calibration value. During calibration of the reader 110, some such embodiments may determine and set the reference detuning signal to configure the power setting of the variable power transmitter 240 at a level that causes the reader to generate a specific field strength for a specific condition. The reference detuning signal level may be determined by a digital control word, which has a fixed value during normal operation and is stored in a non-volatile memory (NVM) 412. The NVM 412 may be part of the reference signal generator 410, or may be accessed by the reference signal generator 410, and the NVM 414 may be implemented with any suitable non-volatile memory (e.g., registers). During normal operation, the value of the digital control word used may be written to the NVM 412 during the calibration process of the reader 110 (i.e., at the end of the calibration process). In this way, the NVM 412 may be considered "programmed" and the reader 100 may be considered "calibrated".

In some embodiments, the reader calibration process is performed under specific load conditions to comply with a specific communication standard, such as the NFC standard. The specific load conditions may include one or more specific reference tags (or other suitable "listeners") and one or more specific reference volumes, which may be specified by the standard. The reference tags may effectively act as variable detuned loads so that the reader performance indicators can be checked using the appropriate load conditions for each test. Regarding the reader field strength, the NFC standard may also specify several specific combinations of reader load conditions to stimulate and check the reader minimum field strength, maximum field strength, and/or other field strength values. These combinations of reader load conditions may be considered as pass/fail criteria for the reader field strength. For example, in order to pass the calibration process, the field strength generated by the reader under each reader load combination must meet the corresponding field strength requirements under the combination, as specified by the standard used for calibration. In general, NFC and other similar standards may provide an indicator of field strength or a way to measure field strength. For example, some standards utilize reference tags to provide an "indicator" of the reader field strength at a specific location within a reference volume. The indicator may simply be a measurable electrical signal in the reference tag that is coupled in some way to the strength of the received reader field. The indicator signal may take any suitable electrical form, such as voltage, current, power, digital word, etc. The different field strength levels may ultimately be explained by the level of the reference tag's indicator signal.

During the reader calibration process, APC can be enabled and any detuned reference signal (e.g., mid-scale of a digital control word) can be selected to start calibration. The specified reader loading conditions can be scanned one by one using the specified reference tags and reference volumes. At each loading combination, the reader field is checked and compared to the specified target. Based on the result of the combination, the detuned reference signal 415 is updated. For example, if the field is above the target, the detuned reference signal 415 is reduced, and vice versa. The cycle of the specified load combination can be repeated for the new value of the detuned reference signal 415. The calibration process can continue (e.g., iterate with each updated detuned reference information 415) until the value of the detuned reference data 415 is found to satisfy all load combinations (e.g., or some threshold defined by the standard is satisfied). This satisfactory value of the detuned reference signal 415 can be stored to the NVM 412. The update of the detuned reference signal 415 from each cycle to the next cycle can be calculated based on a calibration algorithm designed to produce an effective and efficient calibration process. The above calibration process is an example of a calibration process. Other embodiments may use other calibration processes.

Embodiments of the error amplifier 420 may generate an error signal 425 by comparing the detuned signal 215 from the receiver 210 with the reference signal 415 from the reference signal generator 410. In various embodiments, the error amplifier 420 may be implemented in different ways, such as using a transconductance amplifier, a transimpedance amplifier, a voltage-voltage amplifier, a current-current amplifier, and/or any other suitable error amplifier 420. For example, the error signal 425 indicates the deviation of the detuned signal 215 from the reference signal 415. As shown, the error signal 425 passes through the loop filter 430 to generate a power control signal 435 for the variable power transmitter 240. As described herein, the loop filter 430 may be implemented as any suitable type of filter to control the bandwidth and stabilize the loop. For example, the loop filter 430 may include a low-pass filter so that the power control signal 435 may effectively be a loop-filtered version of the error signal 425. The power control signal 435 controls the transmitter power of the variable power transmitter 240, which effectively adjusts the field strength of the NFC link 130. For example, the variable power transmitter 240 generates the instruction signal 244 based on the received data signal 227 and the power control signal 435, and the instruction signal 244 can be passed to the reader passive network 114 and the reader antenna 112 for transmission at the adjusted power level over the NFC link 130. Adjustments to the transmitter power level (e.g., and accordingly, to the field strength) tend to cause corresponding changes in the received response signal from the tag 120, which may ultimately appear as an update to the detuned signal 215 generated by the receiver 210. The APC loop 450 attempts to stabilize the detuned signal 215 to be substantially equal to the reference signal 415, thereby dynamically maintaining the field characteristics within a desired range of values.

FIG5 shows another schematic NFC communication environment 500 of a reader/writer 110 that implements frequency division coordination APC based on transmitter-side sensing according to various embodiments described herein. The NFC communication environment 500 of FIG5 is similar to FIG4, and similar components are marked with the same reference numerals for increased clarity. As shown, the reader/writer 110 and the tag 120 communicate via an NFC link 130. The reader/writer 100 has a reader/writer antenna 112, a reader/writer passive network 114, and a reader/writer transceiver block assembly, including at least one receiver 210, a controller 220, a reference signal generator 410, an error amplifier 420, a loop filter 430, and a variable power transmitter 540. Unlike FIG4, the variable power transmitter 540 of FIG5 also includes one or more transmitter-side detuning sensors 510. For example, the transmitter-side detuning sensor 510 can detect the current transmitter power level, voltage level, current level, etc., and can generate a transmitter-side detuning signal 515 accordingly.

4, an embodiment of the error amplifier 420 generates an error signal 425 by comparing a transmitter-side detuning signal 515 from a variable power transmitter 540 (e.g., from a transmitter-side detuning sensor 510) with a reference signal 415 generated by a reference signal generator 410 (e.g., based on one or more calibration values stored in NVM 412 or other suitable memory). The error signal 425 can be used to generate a power control signal 435 for updating the transmitter power of the variable power transmitter 540 through a loop filter 430. The variable power transmitter 540 can generate a command signal 245 based on the received data signal 227 from the controller 220 (from the receiver 210 path) and the power control signal 435 from the loop filter 430, and the command signal 245 can be passed to the reader passive network 114 and the reader antenna 112 to transmit at an adjusted power level on the NFC link 130.

As described above (e.g., with reference to FIGS. 2 and 3 ), conventional approaches tend to pass the detuning signal 215 to the controller 220 so that the controller 220 can control the timing of the APC updates (i.e., the controller 220 is part of the conventional APC loop). In the embodiments of FIGS. 4 and 5 , the receiver-side detuning signal 215 or the transmitter-side detuning pulse signal 515 is used to generate the power control signal 435 without the involvement of the controller 220. Therefore, dynamic (e.g., continuous) changes in the detuning pulse 215/515 can directly result in dynamic changes in the error signal 425 and the power control signal 425. However, embodiments of the loop filter 430 provide frequency division coordination by effectively slowing down and smoothing changes in the power control signal 435 to produce a signal change that is much slower than any signal change that may be misinterpreted as data by the reader 110 or the tag 120. Some embodiments of the loop filter 430 determine the APC loop 450 bandwidth and filter the error signal 425 accordingly so that the corresponding power control signal 435 is updated at a frequency (fp) much slower than the modulation frequency (fm). For example, the corner frequency of the low-pass filter used as the loop filter 430 can be set to be much lower than the frequency of the data bit rate used by the reader 110 and the tag 120 for communication. When it is mentioned that the loop filter 430 "determines" the APC loop 450 bandwidth, it is meant that the APC loop 450 bandwidth is at least a function of the filter frequency distribution of the loop filter 430. In some embodiments described herein, the APC loop 450 bandwidth is also a function of other factors, such as detuned sensors, current sensors, etc.

6 and 7 include a number of graphs to illustrate the effect of this frequency division coordination in the context of APC in a near field reader. Turning first to FIG. 6, a series of frequency domain graphs 600 are shown. The first graph 600a shows an exemplary carrier frequency (fc) 610, and the second graph 600b shows the modulation bandwidth centered around the modulation frequency (fm) 620. The third graph 600c shows the frequency content of unwanted DC and very low frequency signals caused by the signal encoding scheme and random bit pattern or caused by APC. The bandwidth of these unwanted signals is represented by fp 630. The fourth graph 600d shows that the data band produced by the modulation corresponds to the modulation bandwidth around fc 610 ± fm 620. As long as fp 632 is much lower than fm 622, the filter provides a narrow frequency band around fc 610 that does not overlap with the data band. For example, when the APC update frequency (corresponding to fp 630) is much slower than the data modulation frequency (corresponding to fm 620), the data frame is retained. APC power updates can be effectively centered on frequencies close to DC, well below fm 620. Because the receiver circuitry of the reader 110 and tag 120 is typically designed to decode in the desired data band, very low frequency (substantially DC) APC effects will be filtered out (e.g., by baseband filter selectivity, etc.).

This can be further seen in FIG7. As shown in FIG3, an exemplary unmodulated RF carrier signal 305 and an exemplary modulation signal 315 (e.g., representing a bit stream) are shown as being fed to an amplitude modulation block 310. The amplitude modulation block 310 modulates the unmodulated RF carrier signal 305 according to the modulation signal 315 to generate a modulated carrier signal 320 having a modulation depth 325. Unlike FIG3, an exemplary frequency division coordinated APC block (FDC APC) 730 is shown adjusting the transmit power of the modulated carrier signal 320 according to the loop filtered power control signal 425 to generate a power regulated modulated carrier signal 640. Unlike the sharp edges produced by the conventional APC block 330 discussed in FIG3, the slowly varying power control signal 425 in FIG7 produces corresponding gradual changes in the high and low modulation levels of the power regulated modulated carrier signal 740. This gradual change does not appear as modulation (bit changes) and is less likely to be misinterpreted as data by the reader 110 or the tag 120. Thus, the reader/writer 110 and/or the tag 120 may continue to communicate (eg, may listen) even while APC adjustments are occurring.

The embodiments described above with reference to FIG. 4 and FIG. 5 represent only some methods for implementing frequency division coordinated APC. FIG. 8-10 provide other methods for implementing frequency division coordinated APC. FIG. 8 shows a schematic reader 800 for implementing additional frequency division coordinated APC techniques based on transmitter-side sensing according to various embodiments described herein. The reader 800 can be an implementation of the reader 110 of FIG. 5 or any suitable reader of the environment 100 of FIG. 1 . For example, the reader 800 can be used to implement NFC communication with a tag via an NFC link. As in the embodiments of FIG. 4 and FIG. 5 , the reader 110 has a reader antenna 112, a reader passive network 114, and a reader transceiver block component, including at least a receiver 210, a controller 220, a reference signal generator 410, an error amplifier 420, a loop filter 430, and a variable power transmitter 840.

FIG8 illustrates a specific implementation of a variable power transmitter 840 for facilitating one or more frequency division coordinated APC loops 850. The variable power transmitter 840 may be an implementation of the variable power transmitter 540 of FIG5. As shown, the variable power transmitter 840 may include an encoder 822 coupled to the controller 220. For example, the controller 220 includes a data circuit (e.g., coupled to a memory, etc.) and a clock circuit so that the controller 220 can generate data to be transmitted to the tag 120 and a carrier signal of a carrier frequency. The encoder 822 may generate a bit stream forming a transmission frame based on the data output by the controller 220. The encoder 822 may feed a modulator 824, which generates a modulated carrier 825 based on the encoded bit stream and the carrier signal generated by the controller 220 (or other clock circuit). The modulated carrier 825 is fed to a power amplifier (PA) 810, which generates a command signal 245. The PA 810 may drive the passive network 114 with the command signal 245 , thereby transmitting the command signal 245 over the NFC link 230 via the reader antenna 112 .

PA 810 defines the transmit output power of variable power transmitter 840, and APC loop 850 (or APC loop 850) can be effectively used to control the transmit output power based on transmitter-side detuning sensing. In some embodiments, primary APC loop 850a provides coarse control of the transmit output power of variable power transmitter 840. In some such embodiments, secondary APC loop 850b further provides fine control of the transmit output power of variable power transmitter 840.

A supply voltage (e.g., a direct current (DC) voltage supply) for the PA 810 may be generated using a DC-DC converter 830. The DC-DC converter 830 may convert an external DC supply voltage (VDD_IN) to a desired supply voltage (VDD_PA) 812 for the PA 810. The DC-DC converter 830 may be implemented in any suitable manner, such as using an inductive or capacitive switch mode DC-DC converter, a linear DC-DC converter (e.g., a low dropout (LDO) regulator or other linear regulator), etc. The output power of the PA 810 is highly dependent on the VDD_PA 812. Therefore, controlling the VDD_PA 812 generated by the DC-DC converter 830 may provide a rough control of the transmit output power of the variable power transmitter 840.

By properly adjusting the reader antenna 112 and the external reader passive network 114, the current drawn by the PA 810 can indicate the current detuning condition. As shown, the current sensor 820 can be used to sense the current current drawn by the PA 810 and generate a detuning signal 815 accordingly. In some embodiments, the current sensor 820 is placed in the VDD_PA 812. In other embodiments, the current sensor 820 is integrated in the DC-DC converter 830 or on the main line. For example, the loop bandwidth of the APC loop 850 may be at least partially limited by the DC-DC converter 830, and placing the current sensor 820 in the DC-DC converter, or on the main line, and due to the limited speed of the DC-DC converter 830, it may tend to provide additional bandwidth reduction. This additional bandwidth reduction can allow the size of the loop filter 430 to be reduced. The generated detuning signal 815 can represent the detuning state in any suitable manner (e.g., as a voltage, current, power, digital word, etc.). As in other embodiments (e.g., FIG. 5 ), the detuned signal 815 is fed to the error amplifier 420 (e.g., based on one or more calibration values stored in the NVM 412 or other suitable memory, not explicitly shown) along with the reference signal 415 generated by the reference signal generator 410. The error amplifier 420 may output the error signal 425 to the loop filter 430, which generates the power control signal 435 accordingly.

According to the primary APC loop 850a, the power control signal 435a is fed back to the DC-DC converter 830, which may cause the DC-DC converter 830 to adjust VDD_PA 812. In some embodiments, it is necessary to provide additional (e.g., fine) control over the output transmit power. According to the secondary APC loop 850b, the power control signal 435b can be fed back to the PA strength control of the PA 810 for fine power control. For example, the PA strength can be controlled by having a programmable number of parallel PA810 cells, determining the size of certain devices within the PA 810, controlling certain bias voltages within the PA 810, and/or in any other suitable manner. Basically, both the primary APC loop 850a and the secondary APC loop 850b can adjust the PA 810 current in response to the sensed detuning, so that the PA 810 current is stabilized near the target reference current specified by the reference signal 415.

FIG9 shows an exemplary NFC communication environment 900 with additional power control feedback according to various embodiments described herein. The NFC communication environment 900 may be an alternative embodiment of the environment 400 of FIG4 . As described with reference to FIG4 , the reader 110 and the tag 120 communicate via the NFC link 130 . The reader 100 has a reader antenna 112 , a reader passive network 114 , and a reader transceiver block, which may include at least one receiver 210 , a controller 220 , a reference signal generator 410 , an error amplifier 420 , a loop filter 430 , and a variable power transmitter 240 . The receiver 210 may generate one or more detuning signals 215 using the processed response signal 205 to indicate a detuning condition (e.g., based on the configuration of the tag 120 , a change in the position of the tag 120 relative to the reader 110 , etc.). An embodiment of the error amplifier 420 may generate an error signal 425 by comparing the detuning signal 215 from the receiver 210 with the reference signal 415 generated by the reference signal generator 410 . The error signal 425 may be passed through a loop filter 430 to generate a power control signal 435 for the variable power transmitter 240. The variable power transmitter 240 may generate a command signal 244 based on the data signal 227 and the power control signal 435 received from the controller 220, and the command signal 244 may be passed to the reader passive network 114 and the reader antenna 112 to transmit at an adjusted power level over the NFC link 130.

Unlike the implementation of FIG. 4 , the implementation of FIG. 9 includes additional feedback of the power control signal 435 to the controller 220. In this implementation, the controller 220 is part of the APC loop 950, but the APC loop 950 still works according to the APC of frequency division coordination (rather than time division coordination). In particular, in the implementation of FIG. 4 , the reference signal 415 is a time-invariant signal. For example, the reference signal 415 is a calibration signal that provides a consistent reference. According to FIG. 9 , the controller 220 can generate a reference control signal 915 based on the fed-back power control signal 435. The generated reference control signal 915 is passed to the reference signal generator 410, and the reference signal generator 410 is used to adjust the reference signal 415 based on the reference control signal 915. In this way, the reference signal 415 is a time-varying signal that can be dynamically updated by the controller 220 to further enhance the robustness of the communication. Now, the APC can keep working during the communication frame using a fixed reference signal that relies on the concept of frequency coordination, and keep an uninterrupted long communication frame. Between communication frames, the system controller can freely update the reference signal of the APC based on multiple (e.g., a large number) inputs from the transmitter, receiver, and the APC itself. This can increase the flexibility of the implementation to accommodate unexpected non-ideal situations, emerging standards, etc. For example, such a dynamic reference can be used to account for irregularities, non-monotonicity, and/or any unexpected behavior in the distribution of field strength relative to the detuned signal. Such practical problems may arise from non-idealities in the antenna 112, the passive network 114, the circuit board or other substrate, the amplifier, etc.

FIG. 10 shows an exemplary NFC communication environment 1000 according to various embodiments described herein. The NFC communication environment 1000 may be an alternative implementation of the environment 500 of FIG. 5 (or the reader 800 of FIG. 8 ). As shown, the reader 110 and the tag 120 communicate via an NFC link 130. The reader 110 has a reader antenna 112, a reader passive network 114, and a reader transceiver block assembly, including at least a receiver 210, a controller 220, a reference signal generator 410, an error amplifier 420, a loop filter 430, and a variable power transmitter 540. The variable power transmitter 540 includes one or more transmitter-side detuning sensors 510, which are used to detect a preset effect of detuning on the variable power transmitter 540 (e.g., by detecting current current consumption) and generate a transmitter-side detuning signal 515 accordingly.

The embodiment of the error amplifier 420 generates an error signal 425 by comparing a transmitter-side detuning signal 515 from a variable power transmitter 540 (e.g., from a transmitter-side detuning sensor 510) with a reference signal 415 generated by a reference signal generator 410. The error signal 425 can generate a power control signal 435 for updating the transmitter power of the variable power transmitter 540 through a loop filter 430. The variable power transmitter 540 can generate a command signal 245 based on the data signal 227 received from the controller 220 (from the receiver 210 path) and the power control signal 435 from the loop filter 430, and the command signal 245 can be passed to the reader passive network 114 and the reader antenna 112 to transmit at an adjusted power level on the NFC link 130. Similar to FIG. 9, the implementation of FIG. 10 includes additional feedback of the power control signal 435 to the controller 220. The controller 220 can generate a reference control signal 915 based on the fed-back power control signal 435. The generated reference control signal 915 is passed to the reference signal generator 410, and the reference signal generator 410 is used to adjust the reference signal 415 based on the reference control signal 915. Therefore, as shown in FIG9, the reference signal 415 is a time-varying signal that can be dynamically updated by the controller 220 to further enhance communication robustness.

FIG11 shows a flow chart of an exemplary method 1100 for frequency division coordinated automatic power control of a near field transceiver according to various embodiments described herein. An embodiment of the method 1100 begins at stage 1102 by updating a power control signal according to an update frequency that is at least a function of a filter frequency distribution and is out-of-band relative to a modulation frequency band. In some embodiments, the update at stage 1102 is a dynamic process that can be iterated through some or all of stages 1104-1116 of the method 1100.

Embodiments may proceed at stage 1104 by generating a detuning signal during communication of a signal by a near-field transceiver via a near-field communication link. The detuning signal may correspond to a current field strength of the near-field communication link, which varies in response to a dynamic load on the near-field transceiver by a tag electrically inductively coupled via the near-field communication link. In some embodiments, generation of the detuning signal at stage 1104 is based on sensing an electrical characteristic of a response signal received by the near-field transceiver via the near-field communication link, such that the sensed electrical characteristic indicates a current field strength of the near-field communication link.

At stage 1112, embodiments may generate an error signal by comparing the detune signal to a reference detune level. In some embodiments, at stage 1108, method 1100 may include generating a reference signal indicative of a reference detune level, and the error signal may be generated at stage 1112 by comparing the detune signal to the reference signal. In some embodiments, the reference signal is generated at stage 1108 based at least on the power control signal, such that the reference signal is a time-varying reference signal indicating the reference detune level as an adjustable reference detune level responsive to the power control signal.

At stage 1116, an embodiment may generate a power control signal by filtering the error signal according to a filter frequency distribution. For example, the filter frequency distribution may correspond to a frequency distribution of a low-pass filter, an integrating filter, a filter having a plurality of poles and/or zeros, and/or any suitable filter. The communication of the signal of the near-field transceiver through the near-field communication link may be based on the modulation of the carrier signal in the modulation frequency band. For example, the modulation occurs within a frequency range centered on a frequency defined by a carrier frequency plus a modulation frequency and a carrier frequency minus a modulation frequency, wherein the modulation frequency corresponds to a bit rate, etc. For example, the filter frequency distribution and/or other parameters of the APC loop may effectively set a loop bandwidth, which determines the update frequency of the power control signal. As described herein, the APC loop is designed such that the loop bandwidth causes the update frequency to be far beyond the frequency band relative to the modulation frequency band, so that the receiver and transmitter effectively ignore changes in the power control signal (e.g., regarded as DC).

The communication of the signal may include transmitting the command signal by the near field transceiver through the near field communication link according to the power control signal. In some embodiments, the communication of the signal also includes receiving the response signal by the near field communication link through the near field transceiver during the reception communication frame, and transmitting the command signal during the transmission communication frame. The frequency division coordinated APC described by the method 1100 can allow the updating of the power control signal to occur (e.g., continuously) even during the reception communication frame and/or the transmission communication frame.

As described above, in some embodiments, generating the detuning signal in stage 1104 may be based on sensing a current transmit power characteristic indicating a current field strength of the near field communication link. Some such embodiments further include, at stage 1120, dynamically controlling the power amplifier based on the power control signal, wherein the command signal is amplified by the power amplifier according to the control and transmitted through the near field communication link. In some such embodiments, the adjustable power supply voltage of the power amplifier is dynamically controlled based on the power control signal, wherein the command signal is amplified by the power amplifier at least according to the power supply voltage, and the command signal is transmitted through the near field communication link. For example, generating the detuning signal at stage 1104 is based on sensing a current current level corresponding to the adjustable power supply voltage, so that the adjustable power supply current of the power amplifier is controlled based on the power control signal in response to the current current level. In other such embodiments, the control at stage 1120 is based on the power control signal to dynamically perform fine intensity control on the power amplifier, wherein the command signal is amplified by the power amplifier at least according to the fine intensity control, and the command signal is transmitted through the near field communication link. As described above, the fine intensity control is separated from the power supply voltage of the power amplifier and separated from the gain of the power amplifier. Embodiments may control the adjustable supply voltage of the power amplifier as a coarse amplifier control while controlling the fine intensity control as a fine amplifier control.

It should be understood that when an element or component is referred to as "connected to" or "coupled to" another element or component in this article, it can be connected or coupled to another element or component, or there can also be an intervening element or component. On the contrary, when an element or component is referred to as "directly connected to" or "directly coupled to" another element or component, there is no intervening element or component between them. It should be understood that although the terms "first", "second", "third", etc. can be used to describe various elements and components, these elements, components, and regions should not be limited by these terms. These terms are only used to distinguish an element, component from another element, component. Therefore, the first element and component discussed below can be referred to as the second element and component without departing from the teachings of the present invention. As used herein, the terms "logical low", "low state", "low level", "logical low level", "low" or "0" are used interchangeably. The terms "logical high", "high state", "high level", "logical high level", "high" or "1" are used interchangeably.

As used herein, the terms "a", "an" and "the" may include singular and plural references. It should also be understood that the terms "comprising", "including", "having" and variations thereof, when used in this specification, indicate the presence of the described features, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and/or combinations thereof. In contrast, when the term "consisting of..." is used in this specification, the described features, steps, operations, elements and/or components are described, and additional features, steps, operations, elements and/or components are excluded. In addition, as used herein, the word "and/or" may refer to and may include any possible combination of one or more associated listed items.

Although the present invention is described herein with reference to illustrative embodiments, the description is not intended to be interpreted in a limiting sense. On the contrary, the purpose of the exemplary embodiments is to enable those skilled in the art to better understand the spirit of the present invention. In order not to obscure the scope of the present invention, many details of well-known processes and manufacturing techniques are omitted. With reference to this description, various modifications of the illustrative embodiments and other embodiments will be apparent to those skilled in the art. Therefore, the appended claims are intended to cover any such modifications.

In addition, some features of the preferred embodiments of the present invention can be advantageously used without the corresponding use of other features. Therefore, the above description should be considered as an illustration of the principle of the present invention only, rather than a limitation thereof. Those skilled in the art will be able to conceive of variations of the above-described embodiments that fall within the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments and descriptions discussed above, but is limited by the appended claims and their equivalents.

Claims (21)

1. A transceiver system for near field communication, the transceiver system comprising: a receiver for receiving a response signal via a near field communication link; a transmitter for transmitting a command signal through the near field communication link according to the power control signal, the command signal being generated by modulating a carrier within a modulation frequency band; and A frequency division coordinator is iteratively coupled to the transmitter and is used to: receiving a detuning signal from the receiver and/or from the transmitter; generating an error signal by comparing the detune signal to a reference detune level; and The power control signal is generated by filtering the error signal according to a filter frequency profile such that the power control signal is dynamically updated according to an update frequency that is a function of at least the filter frequency profile and is out-of-band relative to the modulation frequency band. 2. The transceiver system of claim 1, wherein: The receiver is used to receive the response signal during the reception of the communication frame; The transmitter is used to transmit the instruction signal during the transmission of the communication frame; and The frequency division coordinator is used to dynamically update the power control signal so that the power control signal is time-varying during at least a portion of the received communication frame and at least a portion of the transmitted communication frame. 3. The transceiver system of claim 1 , wherein the frequency division coordinator comprises: a reference signal generator, configured to generate a reference signal indicating the reference detuning level; an error amplifier for comparing the detuned signal with the reference signal; and A loop filter is configured to update the power control signal by filtering the error signal according to the filter frequency profile. 4. The transceiver system of claim 1 , wherein: generating, by the receiver, the detuning signal based on sensing an electrical characteristic of the response signal; and The frequency division coordinator is also coupled to the receiver to receive the detuning signal. 5. The transceiver system of claim 1 , wherein: The transmitter comprises one or more detuning sensors for sensing a current transmit power characteristic of the transmitter and generating the detuning signal based on the current transmit power characteristic; and The frequency division coordinator is configured to receive the detuning signal from the transmitter. 6. The transceiver system of claim 5, wherein the transmitter comprises: a power amplifier for amplifying the command signal for transmission via the near field communication link, the amplification being performed based on at least a supply voltage of the power amplifier; A DC-DC converter is configured to receive the power control signal from the frequency division coordinator and control the power supply voltage of the power amplifier based on the power control signal. 7. The transceiver system of claim 6, wherein the transmitter further comprises: Current sensors for: sensing a present current level corresponding to the supply voltage of the power amplifier controlled by the DC-DC converter; and The detune signal is generated based on the present current level. 8. The transceiver system of claim 6, wherein: The power amplifier includes a fine intensity control coupled to the frequency division coordinator to perform control based on the power control signal, and the amplification is further performed according to the fine intensity control. 9. The transceiver system of claim 1 , further comprising: a controller for generating a data signal for transmission via the near field communication link, The transmitter further includes a modulator to generate the instruction signal at least in part by modulating the carrier within the modulation frequency band based on the data signal. 10. The transceiver system of claim 9, wherein: The controller is coupled to the frequency division coordinator to receive the power control signal; The frequency division coordinator includes a reference signal generator coupled to the controller to generate a time-varying reference signal indicating the reference detune level as an adjustable reference detune level based on the power control signal. 11. The transceiver system of claim 1 , wherein the reference detune level is indicated by the frequency division coordinator as a reference signal having the same signal type as the detune signal, the same signal type being one or more of a power level, a voltage level, a current level, or a digital word. 12. A near field reader/writer system, comprising: A reader/writer antenna and a reader/writer passive network, coupled with the transceiver system according to claim 1, wherein the reader/writer antenna and the reader/writer passive network are used to: When the proximity of the tag to the near field reader/writer system is within a threshold distance, establishing the near field communication link by inductive coupling with the tag, the establishing causing a variable load on the near field reader/writer system by the tag based at least on the proximity; receiving the response signal via the near field communication link and communicating the response signal to the receiver; and The command signal is received from the transmitter and transmitted via the near field communication link. 13. A method for frequency division coordinated automatic power control of a near field transceiver, the method comprising: The power control signal is updated iteratively according to an update frequency that is a function of at least one filter frequency profile and is out-of-band with respect to the modulation frequency band: generating a detuning signal during communication of signals by the near field transceiver via a near field communication link, such that the detuning signal corresponds to a current field strength of the near field communication link, the current field strength varying in response to a dynamic load on the near field transceiver by a tag inductively coupled via the near field communication link; generating an error signal by comparing the detune signal to a reference detune level; and generating the power control signal by filtering the error signal according to the filter frequency profile, The signal communication performed by the near field transceiver through the near field communication link is based on the modulation of the carrier signal in the modulation frequency band, and includes the near field transceiver transmitting a command signal through the near field communication link according to the power control signal. 14. The method according to claim 13, wherein: The signal communication further includes receiving a response signal by the near field transceiver via the near field communication link during the reception of the communication frame; The transmitting of the instruction signal is during the transmitting communication frame; and The updating of the power control signal is during at least one of the receiving communication frames or at least one of the transmitting communication frames. 15. The method according to claim 13, further comprising: generating a reference signal indicative of the reference detune level, The generating of the error signal is performed by comparing the detuning signal with the reference signal. 16. The method of claim 15, wherein: The reference signal is generated based at least on the power control signal such that the reference signal is a time varying reference signal indicating the reference detune level as an adjustable reference detune level in response to the power control signal. 17. The method of claim 13, wherein: The signal communication further includes receiving, by the near field transceiver, a response signal via the near field communication link; The generating the detuning signal is based on sensing an electrical characteristic of the response signal indicative of the current field strength of the near field communication link. 18. The method of claim 13, wherein: The generating the detuning signal is based on sensing a current transmit power characteristic indicative of the current field strength of the near field communication link. 19. The method according to claim 18, further comprising: dynamically controlling an adjustable power supply voltage of the power amplifier based on the power control signal, Wherein, transmitting the command signal through the near field communication link includes amplifying the command signal through the power amplifier at least according to the power supply voltage. 20. The method of claim 19, wherein: The generating of the detuning signal is based on sensing a present current level corresponding to the adjustable supply voltage, such that the controlling of the adjustable supply voltage of the power amplifier based on the power control signal is responsive to the present current level. 21. The method of claim 18, further comprising: dynamically controlling a fine intensity control of a power amplifier based on the power control signal, the fine intensity control being separate from a supply voltage of the power amplifier and separate from a gain of the power amplifier, Wherein, transmitting the command signal via the near field communication link comprises amplifying the command signal via the power amplifier at least according to the refined intensity control.