Near-field communication device and method for detecting its resonant frequency

Abstract

A near field communication (NFC) device includes a resonator having an antenna and a matching circuit, a transmitter, and a frequency detector. The transmitter generates a sense voltage signal at the resonator. Regarding a plurality of measurement periods, each of which includes an on period and an off period, the transmitter is enabled during the on period to output a radio frequency (RF) signal to the resonator and disabled during the off period. The frequency detector detects a resonant frequency of the resonator based on the sense voltage signal. The resonant frequency is accurately detected by measuring the resonant frequency during a plurality of measurement periods. Additionally, the resonant frequency is effectively detected by using the transmitter established in the NFC device to generate the sense voltage signal.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2019 - 0174890, filed with the Korean Intellectual Property Office (KIPO) on December 26, 2019, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] Some example embodiments generally relate to semiconductor integrated circuits, and more particularly to near - field communication (NFC) devices and / or methods for detecting the resonance frequency of an NFC device.

[0004] Near - field communication (NFC) technology is / includes short - range wireless communication technology. With the development of NFC technology, NFC devices have been more commonly adopted in mobile devices. The resonance frequency of a resonator included in an NFC device is determined by a combination of RF elements in the resonator, and the resonance frequency may vary due to deviations in the characteristics of the RF elements. When the resonance frequency approaches the center value of the optimal frequency band, the signal quality of the NFC device is enhanced, and when the resonance frequency is away from the center value, signal distortion of the NFC device occurs. It may be desirable or expected to compensate for the distorted signal by detecting the resonance characteristics of the NFC device to ensure uniform performance of the NFC device. Conventionally, an external device using a phase - delay unit is used to detect the resonance frequency, and thus the detection resolution is reduced. Summary of the Invention

[0005] Some example embodiments may provide a near - field communication (NFC) device and / or a method capable of effectively detecting the resonance frequency of a resonator included in an NFC device.

[0006] According to some example embodiments, a near - field communication (NFC) device includes: a resonator including an antenna and a matching circuit; a transmitter configured to generate a sense voltage signal at the resonator during a plurality of measurement periods, each of the plurality of measurement periods including an on - period and an off - period, the transmitter being enabled to output a radio - frequency (RF) signal to the resonator during the on - period and prohibited from outputting an RF signal to the resonator during the off - period; and a frequency detector configured to detect the resonance frequency of the resonator based on the sense voltage signal.

[0007] According to some example embodiments, a method of detecting a resonant frequency of a Near Field Communication (NFC) device includes: during a plurality of measurement periods, each including an on-period and an off-period, generating a sensed voltage signal at a resonator included in the NFC device by enabling a transmitter included in the NFC device to output a radio frequency (RF) signal to the resonator during the on-period and disabling the transmitter during the off-period; and detecting the resonant frequency of the resonator based on the sensed voltage signal.

[0008] According to some example embodiments, a method of detecting a resonant frequency of a Near Field Communication (NFC) device includes: during a plurality of measurement periods, each including an on-period and an off-period, generating an RF enable signal that is activated during the on-period and deactivated during the off-period; generating a sensed voltage signal based on the RF enable signal, generating a sensed voltage at the resonator by enabling a transmitter included in the NFC device to output a radio frequency (RF) signal to a resonator included in the NFC device during the on-period and by disabling the transmitter during the off-period; generating a clock signal that toggles in accordance with oscillations of the sensed voltage signal; generating a clock count by counting the number of clocks of the clock signal during an activation time interval of a count enable signal; and providing the resonant frequency based on the clock count.

[0009] The NFC device and / or method according to some example embodiments may more accurately detect the resonant frequency by measuring the resonant frequency during a plurality of measurement periods. The resonant frequency may be more accurately detected by converting the sensed voltage signal into a clock signal and counting the number of clocks of the clock signal.

[0010] The NFC device and / or method according to some example embodiments may effectively or more effectively detect the resonant frequency by generating a sensed voltage signal using a transmitter established in the NFC device.

[0011] The NFC device and / or method according to some example embodiments may effectively or more effectively detect the resonant frequency without an external device by implementing a frequency detector as an on-chip component. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Some example embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

[0013] Figure 1 is a flowchart illustrating a method of detecting a resonant frequency of a Near Field Communication (NFC) device according to some example embodiments.

[0014] Figure 2 is a diagram illustrating an NFC device according to some example embodiments.

[0015] Figure 3 is a timing diagram illustrating a sensed voltage signal for detecting a resonant frequency of an NFC device according to some example embodiments.

[0016] Figure 4 is a block diagram illustrating a frequency detector according to some example embodiments.

[0017] Figure 5 is a timing diagram illustrating a method for detecting a resonant frequency of an NFC device according to some example embodiments.

[0018] Figure 6 is a circuit diagram illustrating an example embodiment of a count control circuit included in an NFC device according to some example embodiments.

[0019] Figure 7 is an illustration Figure 6 of the operation of the count control circuit.

[0020] Figure 8 is a timing diagram illustrating a method for detecting a resonant frequency of an NFC device according to some example embodiments.

[0021] Figure 9 is a circuit diagram illustrating an example embodiment of a count control circuit included in an NFC device according to some example embodiments.

[0022] Figure 10 is an illustration Figure 9 of the operation of the count control circuit.

[0023] Figure 11 is a timing diagram illustrating a method for detecting a resonant frequency of an NFC device according to some example embodiments.

[0024] Figure 12 and Figure 13 is a diagram illustrating an example embodiment of a mapping table for detecting a resonant frequency of an NFC device according to some example embodiments.

[0025] Figure 14 is a diagram illustrating an NFC device according to some example embodiments.

[0026] Figure 15 is a diagram for describing the frequency characteristics of a resonator included in an NFC device.

[0027] Figure 16 is a diagram illustrating an example embodiment of a transmitter included in an NFC device according to some example embodiments.

[0028] Figure 17 is for describing Figure 16 the operation of the transmitter.

[0029] Figure 18 FIG. is a diagram illustrating an NFC device according to some example embodiments.

[0030] Figure 19 and Figure 20 FIG. is a diagram illustrating a test system according to some example embodiments.

[0031] Figure 21 FIG. is a block diagram illustrating an electronic device according to some example embodiments. DETAILED DESCRIPTION

[0032] Various example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout. Repeated description may be omitted.

[0033] Figure 1 FIG. is a flowchart illustrating a method of detecting a resonance frequency of a near field communication (NFC) device according to some example embodiments.

[0034] Referring Figure 1 , for a plurality of measurement periods, each measurement period including an on period and an off period, a sensing voltage signal (S100) is generated at a resonator included in the NFC device by enabling a transmitter included in the NFC device to output a radio frequency (RF) signal to the resonator during the on period and by disabling the transmitter during the off period.

[0035] The sensing voltage signal may oscillate at a transmission frequency during the on period, where the transmission frequency is based on the RF signal. Additionally, the sensing voltage signal may oscillate at a resonance frequency during the off period, where the resonance frequency is based on an induced electromotive force induced by the RF signal in the resonator. Further description of the generation of the sensing voltage signal will be made hereinafter with reference to Figure 2 and Figure 3 .

[0036] The resonance frequency of the resonator is detected based on the sensing voltage signal (S200).

[0037] According to some example embodiments, an NFC device and / or method may more accurately detect a resonance frequency by measuring the resonance frequency during a plurality of measurement periods. The resonance frequency may be more accurately detected by converting the sensing voltage signal into a clock signal and counting the number of clocks (e.g., the number of cycles) of the clock signal.

[0038] In some example embodiments, the resonance frequency may be detected by converting the sensing voltage signal into a clock signal and counting the number of clocks of the clock signal. Accordingly, frequency detection accuracy and efficiency may be enhanced.

[0039] In some example embodiments, the resonance frequency may be calculated based on the time interval of the on-time period, the time interval of the off-time period, the number of multiple measurement periods, and / or the measured clock counts.

[0040] In some example embodiments, the resonance frequency may be determined based on a mapping table indicating a mapping relationship between multiple values of clock counts and multiple values of the resonance frequency.

[0041] Figure 2 FIG. is a diagram illustrating an NFC device according to some example embodiments.

[0042] Reference Figure 2 , the NFC device 10 includes a resonator 100 and an NFC chip 200. The NFC chip 200 includes a transmitter Tx 300, a frequency detector FDET 400, and a controller CON 500. Figure 2 Only some components such as those for detecting the resonance frequency are illustrated, and other components such as a receiver are omitted. Examples of detailed configurations will be described with reference to Figure 14 . The transmitter Tx 300, the frequency detector FET 400, and the controller 500 may be implemented in hardware and / or software. In addition, some functions of the components of the NFC chip 200 may be performed by other components of the NFC chip 200; the example embodiments are not limited thereto.

[0043] The resonator 100 may include a resonance circuit 110 having an inductance component (inductor) L and a matching circuit 150 having a capacitor C1. Figure 2 A non-limiting example of the resonator 100 is illustrated, and the configuration of the resonator 100 may be implemented in various ways.

[0044] The transmitter 300 may be coupled to the resonator 100 through first and second transmission terminals TX1 and TX2.

[0045] In a normal mode for communicating with an external device, the transmitter 300 may output an RF signal to the resonator 100 by modulating a signal from the controller 500, and a receiver (not shown) may demodulate the RF signal received through the resonator 100 to provide a demodulated signal to the controller 500.

[0046] In a measurement mode for detecting the resonance frequency, the transmitter 300 may generate a sensed voltage signal VS at the resonator 100. Regarding multiple measurement periods, each of which includes an on-time period and an off-time period, the transmitter 300 may be enabled during the on-time period to output an RF signal to the resonator 100, and the transmitter 300 may be disabled during the off-time period to generate the sensed voltage signal VS.

[0047] For example, the sensed voltage signal VS may correspond to the voltage across the capacitor C1. Figure 2 FIG. shows a non-limiting example of a differential transmit and receive scheme, and it will be understood that the example embodiments may be applicable to a single-ended transmit / receive scheme.

[0048] In some example embodiments, as will be described below with reference to Figure 3 the transmitter 300 may generate the sensed voltage signal VS based on an RF enable signal RFEN that is activated during an on period and deactivated during an off period. For example, the RF enable signal RFEN may be provided from the controller 500, but the example embodiments are not limited thereto, and the RF enable signal RFEN may be provided externally from other systems and / or Figure 3 components illustrated therein.

[0049] The frequency detector 400 may be coupled to the resonator 100 through first and second power terminals L1 and L2. The frequency detector 400 may detect the resonant frequency fr of the resonator 100 based on the sensed voltage signal VS.

[0050] In some example embodiments, the resonant frequency fr may be used as information for controlling the operation of the NFC device 10. For example, as will be described below with reference to Figure 15 and Figure 16 the detection result of the resonant frequency fr may be used to control the pull-down amount of the transmitter 300. Alternatively or additionally, as will be described below with reference to Figure 18 the detection result of the resonant frequency fr may be used to adjust the resonant frequency fr.

[0051] In some example embodiments, the resonant frequency fr may be provided to an external device to determine a fault of the NFC device 10 and / or improve the design of the NFC device 10.

[0052] The controller 500 may include a processor, a memory block, etc. for controlling the overall operation of the NFC device 10. The controller 500 may provide a signal for controlling the frequency detector 400 and receive the detected resonant frequency fr or information about the resonant frequency fr from the frequency detector 400. Figure 2The NFC device 10 illustrated in the figure can communicate with an external device via the NFC scheme. In some example embodiments, the NFC device 10 may perform operations of detecting whether an NFC card (not illustrated) is close to the NFC device 10 (e.g., within a certain threshold proximity range of the NFC device 10), and / or detecting whether an NFC reader (not illustrated) is close to the NFC device 10. These operations between the NFC card / tag and the NFC device are alternatively and repeatedly performed. If and / or when the NFC device 10 detects that the NFC reader is close to the NFC device 10, the NFC device 10 may operate in card mode, in which the NFC device 10 operates as a card. In card mode, the NFC device 10 may communicate data (e.g., transmit and receive data) with the NFC reader using the electromagnetic wave EMW emitted by the NFC reader. Alternatively, if and / or when the NFC device 10 detects that the NFC card is close to the NFC device 10 (e.g., within the threshold proximity range of the NFC device 10), the NFC device 10 may operate in reader mode, in which the NFC device operates as an NFC reader. In reader mode, the NFC device 10 may emit an electromagnetic wave EMW to communicate data with the NFC card.

[0053] In reader mode, the resonator 100 may emit an electromagnetic wave EMW to communicate data with the NFC card. In reader mode, the NFC chip 200 may provide an output current and / or a drive current to the resonator 100, and the resonator 100 may emit an electromagnetic wave EMW corresponding to the drive current to communicate with the NFC card. Since the NFC card includes a resonant circuit, and the resonant circuit includes an antenna having an inductive component and a resonant capacitor, mutual inductance may occur between the resonator 100 and the NFC card in a position close to the resonator 100 while the resonator 100 emits the electromagnetic wave EMW. Therefore, an antenna voltage may be generated at the resonant circuit of the resonator 100 through the mutual inductance with the NFC card.

[0054] Figure 3 is a timing diagram of a sensed voltage signal for detecting the resonant frequency of an NFC device according to some example embodiments.

[0055] Reference Figure 3 , the measurement enable signal MEN may be activated during a plurality of measurement periods T1 to TN. For example, the measurement enable signal MEN may be activated at a logic high level. The measurement enable signal MEN may be generated and used in the controller 500 in Figure 2 and provided to the frequency detector 400.

[0056] Each of a plurality of measurement periods T1 to TN may include an on period TON and an off period TOFF. The RF enable signal RFEN may be activated during the on period TON and deactivated during the off period TOFF. The RF enable signal RFEN may be generated by the controller 500 and then provided to the transmitter 300. The on period TON may be longer than, shorter than, or the same as the amount of time of the off period TOFF.

[0057] Based on the RF enable signal RFEN, the transmitter 300 may be enabled to output an RF signal to the resonator 100 during the on period TON, and the transmitter 300 may be disabled during the off period TOFF, thereby generating a sensed voltage signal VS at the resonator 100. Even if the RF signal is blocked during the off period TOFF, the sensed voltage signal VS may maintain oscillation at the end time point of the on period TON by the induced electromotive force caused in the resonator 100.

[0058] As a result, the sensed voltage signal VS may oscillate at the transmission frequency fc during the on period TON based on the RF signal, and may oscillate at the resonance frequency fr during the off period TOFF based on the induced electromotive force caused by the RF signal in the resonator 100.

[0059] As will be described below, the frequency detector 400 may detect the oscillation frequency of the sensed voltage signal VS during the off period TOFF as the resonance frequency fr.

[0060] Figure 4 is a block diagram illustrating a frequency detector according to some example embodiments.

[0061] Reference Figure 4 , the frequency detector 400 may include a clock extractor 410, a counter 420, and a frequency generator 430. The frequency detector 400, the clock extractor 410, the counter 420, and the frequency generator 430 may include: processing circuitry, such as hardware including logic circuitry; a hardware / software combination such as a processor executing software; or a combination thereof.

[0062] The clock extractor 410 may generate a clock signal CK that toggles according to the oscillation of the sensed voltage signal VS. A scheme for generating the clock signal CK based on the oscillation signal of the sensed voltage signal VS is well known to those skilled in the art, and the configuration of the clock extractor 410 may be implemented in various ways.

[0063] The counter 420 may generate a clock count CNT by counting the number of clocks (e.g., toggles) of the clock signal CK. In some example embodiments, the counter 420 may receive a count enable signal CEN and may generate a clock count CNT by counting the number of clocks during an active time interval of the count enable signal CEN. The scheme of counting the number of clocks of the clock signal is well known to those skilled in the art and the configuration of the counter 420 may be implemented in various ways.

[0064] The frequency generator 430 may provide a resonance frequency fr based on the clock count CNT.

[0065] In some example embodiments, the frequency generator 430 may determine the resonance frequency fr by calculating the resonance frequency fr based on the time interval of the turn-on period TON, the time interval of the turn-off period TOFF, the number of multiple measurement periods T1 to TN, and the measured clock count CNT. In this case, the frequency detector 430 may include simple operation logic for calculation. The operation logic may be implemented as hardware, software, or a combination thereof.

[0066] In some example embodiments, the frequency generator 430 may determine the resonance frequency fr based on a mapping table MTAB indicating the mapping relationship between multiple values of the clock count CNT and multiple values of the resonance frequency fr. In this case, the frequency generator 430 may include a memory storing the mapping table MTAB and a circuit (not shown) for extracting the value of the resonance frequency fr corresponding to the measured clock count CNT from the memory.

[0067] Figure 5 is a timing diagram illustrating a method of detecting the resonance frequency of an NFC device according to some example embodiments.

[0068] Reference Figure 5 , the measurement enable signal MEN may be activated during multiple measurement periods T1 to TN. For example, the measurement enable signal MEN may be activated at a logic high level. It may be generated and used in the controller 500 in Figure 2 and the measurement enable signal MEN may be provided to the frequency detector 400.

[0069] Each of the multiple measurement periods T1 to TN may include a turn-on period TON and a turn-off period TOFF. The RF enable signal RFEN may be activated during the turn-on period TON and deactivated during the turn-off period TOFF. The RF enable signal RFEN may be generated by the controller 500 and then provided to the transmitter 300. The turn-on period TON may be longer than, shorter than, or the same as the amount of time of the turn-off period TOFF.

[0070] Based on the RF enable signal RFEN, the transmitter 300 can be enabled during the on-time period TON to output an RF signal to the resonator 100, and can be disabled during the off-time period TOFF, so that a sensed voltage signal VS is generated at the resonator 100. Even if the RF signal is blocked during the off-time period TOFF, the sensed voltage signal VS can maintain oscillation through the induced electromotive force caused in the resonator 100 at the end time point of the on-time period TON.

[0071] Figure 4 The clock extractor 410 therein can generate a clock signal CK that toggles according to the oscillation of the sensed voltage signal VS. As described above, the sensed voltage signal VS can oscillate at the transmission frequency fc during the on-time period TON based on the RF signal, and can oscillate at the resonance frequency fr during the off-time period TOFF based on the induced electromotive force caused by the RF signal in the resonator 100. Therefore, the clock signal CK can oscillate at the transmission frequency fc during the on-time period TON and at the resonance frequency fr during the off-time period TOFF.

[0072] Figure 4 The counter 420 therein can generate a clock count CNT by counting the number of clocks (e.g., the number of transmissions) during the activation time interval of the count enable signal CEN. In some example embodiments, the count enable signal CEN can be activated during a plurality of measurement time periods T1 to TN regardless of the on-time period TON and the off-time period TOFF. In other words, the count enable signal CEN can be substantially the same as the measurement enable signal MEN. In this case, the time interval for counting the number of clocks corresponds to N*tc1, where N indicates the number of the plurality of measurement time periods T1 to TN and tc1 indicates the cycle time of each measurement time period.

[0073] The resonance frequency fr can be determined by calculating the resonance frequency fr based on the time interval of the on-time period TON, the time interval of the off-time period TOFF, the number of the plurality of measurement time periods T1 to TN, and the measured clock count CNT.

[0074] In Figure 5 this case, the clock count CNT and the resonance frequency fr can satisfy Equation 1.

[0075] Formula 1

[0076] CNT*(ton / toff)=(N*toff) / Tr=N*toff*fr

[0077] In Equation 1, fr indicates the resonance frequency, CNT indicates the clock count, N indicates the number of multiple measurement periods, ton indicates the time interval of each on-period, toff indicates the time interval of each off-period, and Tr indicates the resonance cycle period and corresponds to 1 / fr.

[0078] Therefore, Figure 4 the frequency generator 430 in Figure 4 can determine the resonance frequency fr through Equation 2.

[0079] Formula 2

[0080] fr = (CNT * ton) / (N * toff 2 )

[0081] Figure 6 FIG. is a circuit diagram of an exemplary embodiment of a count control circuit included in an NFC device according to some exemplary embodiments, and Figure 7 is a timing diagram illustrating Figure 6 the operation of the count control circuit.

[0082] Referring to Figure 6 and Figure 7 , the count control circuit 600 may include an inverter 610 and an AND logic gate 620. The count control circuit 600 may be included in Figure 2 the controller 500 or the frequency detector 400 in Figure 2 . Figure 6 This is a non-limiting exemplary embodiment, and the configuration of the count control circuit 600 may be implemented in various ways.

[0083] The inverter 610 may generate an inverted RF enable signal / RFEN by inverting the RF enable signal RFEN that is activated during the on-period TON and deactivated during the off-period TOFF.

[0084] The AND logic gate 620 may generate a count enable signal CEN by performing an AND logic operation on the measurement enable signal MEN and the inverted RF enable signal / RFEN, where the measurement enable signal MEN is activated during multiple measurement periods T1 to TN.

[0085] Therefore, the count enable signal CEN may be deactivated during the on-period TON and activated during the off-period TOFF.

[0086] Referring to Figure 8 , a method for detecting the resonance frequency of an NFC device using Figure 6 and Figure 7 the count enable signal CEN can be described.

[0087] Figure 8is a timing diagram illustrating a method of detecting a resonance frequency of an NFC device according to some example embodiments.

[0088] Reference Figure 8 , the measurement enable signal MEN can be activated during a plurality of measurement periods T1 to TN. For example, the measurement enable signal MEN can be activated with a logic high level.

[0089] Each of the plurality of measurement periods T1 to TN can include a turn-on period TON and a turn-off period TOFF. The RF enable signal RFEN can be activated during the turn-on period TON and deactivated during the turn-off period TOFF. The turn-on period TON can be longer than, shorter than, or the same as the time amount of the turn-off period TOFF.

[0090] Based on the RF enable signal RFEN, the transmitter 300 can be enabled during the turn-on period TON to output an RF signal to the resonator 100, and can be disabled during the turn-off period TOFF, thus generating a sensed voltage signal VS at the resonator 100.

[0091] Figure 4 The clock extractor 410 in can generate a clock signal CK that toggles according to the oscillation of the sensed voltage signal VS. The clock signal CK can oscillate at a transmission frequency fc during the turn-on period TON and at a resonance frequency fr during the turn-off period TOFF.

[0092] Figure 4 The counter 420 in can generate a clock count CNT by counting the number of clocks (e.g., the number of transitions of the clock signal CK) during the activation time interval of the count enable signal CEN. In some example embodiments, the count enable signal CEN can be deactivated during the turn-on period TON and activated during the turn-off period TOFF. In this case, the time interval for counting the number of clocks corresponds to N*tc2, where N indicates the number of the plurality of measurement periods T1 to TN and tc2 indicates the time interval of each turn-off period TOFF.

[0093] The resonance frequency fr can be determined by calculating the resonance frequency fr based on the time interval of the turn-off period TOFF, the number of the plurality of measurement periods T1 to TN, and the measured clock count CNT.

[0094] In Figure 8 's case, the clock count CNT and the resonance frequency fr satisfy Equation 3.

[0095] Formula 3

[0096] CNT = (N*toff) / Tr = N*toff*fr

[0097] In Equation 3, fr indicates the resonance frequency, CNT indicates the clock count, N indicates the number of multiple measurement periods, toff indicates the time interval of each off period, and Tr indicates the resonance cycle period and corresponds to 1 / fr.

[0098] Therefore, Figure 4 the frequency generator 430 in

[0099] Formula 4

[0100] fr = CNT / (N * toff)

[0101] Figure 9 is a circuit diagram of an exemplary embodiment of a count control circuit included in an NFC device according to some exemplary embodiments, and Figure 10 is a timing diagram illustrating Figure 9 the operation of the count control circuit.

[0102] Referring to Figure 9 and Figure 10 , the count control circuit 601 may include a delay circuit 611, an OR logic gate 621, an inverter 631, and an AND logic gate 641. The count control circuit 601 may be included in Figure 2 the controller 500 and / or the frequency detector 400 in Figure 9 This is a non-limiting exemplary embodiment, and the configuration of the count control circuit 601 may be implemented in various ways.

[0103] The delay circuit 611 may generate a first signal S1 by delaying an RF enable signal RFEN that is activated during an on period TON and deactivated during an off period TOFF.

[0104] The OR logic gate 621 may generate a second signal S2 by performing an OR logic operation on the RF enable signal RFEN and the first signal S1.

[0105] The inverter 631 may generate a third signal S3 by inverting the second signal S2.

[0106] The AND logic gate 641 may generate a count enable signal CEN by performing an AND logic operation on a measurement enable signal MEN and the third signal S3, where the measurement enable signal MEN is activated during multiple measurement periods T1 to TN.

[0107] Therefore, the count enable signal CEN may be activated at a time point after a delay time td from the start time point of the off period TOFF, and may be deactivated at the start time point of the on period TON.

[0108] Reference Figure 11 , a method of detecting the resonance frequency of an NFC device by using a count enable signal CEN that can describe the use of Figure 9 and Figure 10 can be described.

[0109] Figure 11 is a timing diagram illustrating a method of detecting the resonance frequency of an NFC device according to some example embodiments.

[0110] Reference Figure 11 , the measurement enable signal MEN can be activated during a plurality of measurement periods T1 to TN. For example, the measurement enable signal MEN can be activated at a logic high level.

[0111] Each of the plurality of measurement periods T1 to TN may include a turn-on period TON and a turn-off period TOFF. The RF enable signal RFEN can be activated during the turn-on period TON and deactivated during the turn-off period TOFF. The turn-on period TON may be longer than, shorter than, or the same as the amount of time of the turn-off period TOFF.

[0112] Based on the RF enable signal RFEN, the transmitter 300 can be enabled during the turn-on period TON to output an RF signal to the resonator 100, and can be disabled during the turn-off period TOFF, thereby generating a sensed voltage signal VS at the resonator 100.

[0113] Figure 4 The clock extractor 410 in can generate a clock signal CK that toggles according to the oscillation of the sensed voltage signal VS. The clock signal CK can oscillate at a transmission frequency fc during the turn-on period TON and oscillate at a resonance frequency fr during the turn-off period TOFF.

[0114] Figure 4 The counter 420 in can generate a clock count CNT by counting the number of clocks during the activation time interval of the count enable signal CEN. In some example embodiments, the count enable signal CEN can be activated at a time point after a delay time td from the start time point of the turn-off period TOFF, and deactivated at the start time point of the turn-on period TON. In this case, the time interval for counting the number of clocks corresponds to N*tc3, where N indicates the number of the plurality of measurement periods T1 to TN and tc3 indicates the activation time interval of the count enable signal CEN.

[0115] The resonant frequency fr can be determined by calculating the resonant frequency fr based on the activation time interval of the count enable signal CEN, the number of multiple measurement periods T1 to TN, and the measured clock count CNT. The calculation is substantially the same as that described in reference formulas 3 and 4, except that the time interval toff of the off period TOFF in formulas 3 and 4 should be replaced by the activation time interval tc3 of the count enable signal CEN.

[0116] Even if the RF signal from the transmitter is blocked, during the transition period corresponding to the initial part of the off period TOFF, the oscillation frequency of the sensed voltage signal VS can be slightly different from the resonant frequency fr. By delaying the start of the activation of the count enable signal CEN by a delay time td, the clocks during the transition period can be excluded from the measurement of the clock count CNT, and thus a more accurate resonant frequency fr can be detected.

[0117] Figure 12 and Figure 13 FIG. is a diagram illustrating an example embodiment of a mapping table for detecting the resonant frequency of an NFC device according to some example embodiments.

[0118] Figure 12 and Figure 13 FIG. illustrates an example of a mapping table MTAB indicating the mapping relationship between multiple values of the clock count CNT and multiple values of the resonant frequency fr, and three antenna characteristics X1, Y2, and Z3. According to some example embodiments, the mapping table MTAB can be obtained by measuring the resonant frequency fr using an external device and measuring the clock count CNT.

[0119] A real NFC device such as the NFC device 10 may have a fixed one antenna characteristic, and only the mapping relationship corresponding to the fixed one antenna characteristic may be included in the mapping table. Figure 12 and Figure 13 The measured values in can be fitted to a linear function and / or a non-linear function and a more detailed mapping table can be obtained.

[0120] The above frequency generator 430 can store the mapping table MTAB, and can determine the resonant frequency fr corresponding to the measured clock count CNT based on the mapping table MTAB.

[0121] The resonant frequency fr obtained according to some example embodiments can be provided to an external device, and the resonant frequency fr can be used to determine the failure of the NFC device. For example, when the NFC device uses a frequency of 13.56 MHz, the normal range of the resonant frequency fr can be set to 13 MHz to 14 MHz. If the measured resonant frequency fr is outside the normal range, the NFC device can be determined to be a faulty device.

[0122] Figure 14 FIG. illustrates an NFC device according to some example embodiments. In Figure 14 are illustrated elements for operating the NFC device 10a in reader mode and elements for operating the NFC device 10a in card mode.

[0123] Referring Figure 14 , the NFC device 10a includes a resonator 100 and an NFC chip 200a.

[0124] The NFC chip 200a is coupled to the resonator 100 via a first power terminal L1, a second power terminal L2, a first transmit terminal TX1, a second transmit terminal TX2, and a receive terminal RX. The resonator 100 includes: a resonance circuit 110 having an antenna L and a first capacitor C1; and a matching circuit 120 coupled to the resonance circuit 110, the first transmit terminal TX1, and the second transmit terminal TX2, and including a second capacitor C2 and a third capacitor C3 to perform impedance matching. The resonator 100 further includes: a first filter 130 coupled to the resonance circuit 110 and the receive terminal RX, the first filter 130 including a fourth capacitor C4; and a second filter 140 coupled to the resonance circuit 110, the first power terminal L1, and the second power terminal L2, the second filter including a fifth capacitor C5 and a sixth capacitor C6. Figure 14 The configuration of the resonator 100 illustrated in is merely an example, and the configuration of the resonator 100 according to some example embodiments may not be limited to the above, but various modifications may be made.

[0125] The NFC chip 200a may perform signal transmission operations and signal reception operations via the first power terminal L1 and the second power terminal L2 in card mode, perform signal transmission operations via the first transmit terminal TX1 and the second transmit terminal TX2 in reader mode, and perform signal reception operations via the receive terminal RX in reader mode.

[0126] The NFC chip 200a includes a processor 220, a memory 230, a first demodulator 241, a first modulator 242, an oscillator 243, a mixer 244, a demultiplexer 245, a transmitter 250, a regulator 260, a frequency detector 400, a rectifier 271, a regulator 273, a power switch PSW, a second demodulator 281, and a second modulator 283.

[0127] The processor 220 may control the overall operation of the NFC chip 200a. The processor 220 may operate by receiving a first power supply voltage VDD1 from a power source such as a battery.

[0128] When performing a signal reception operation in the active mode (e.g., simultaneously with NFC device 10a operating in the active mode), the demodulator 241 generates received data RD by demodulating the signal provided from the resonator 100 through the reception terminal RX to provide the received data RD to the processor 220. The processor 220 may store the received data RD in the memory 230.

[0129] When performing a signal transmission operation in the active mode, the processor 220 reads transmission data TD from the memory 230 to provide the transmission data TD to the modulator 242, and the modulator 242 modulates the transmission data TD to provide a modulated signal. Additionally, the oscillator 243 generates a carrier signal CW having a frequency corresponding to the carrier frequency (e.g., 13.56 MHz), the demultiplexer 245 may provide the carrier signal CW to the mixer 244 in response to a selection signal SS, and the mixer 244 may combine the carrier signal CW with the modulated signal to generate a transmitted modulated signal TMS.

[0130] In each of the preset (or, alternatively, variable) phase and the detection phase of the standby mode, the demultiplexer 245 may provide the carrier signal CW to the transmitter 250 in response to a selection signal SS from the processor 220, and the transmitter 250 may generate a transmission signal TS based on the carrier signal CW to perform a detection operation for detecting an NFC tag.

[0131] The transmitter 250 is coupled between the transmission power supply voltage TVDD and the ground voltage GND. The transmitter 250 may receive the carrier signal CW from the demultiplexer in the standby mode and generate a transmission signal TS corresponding to the carrier signal CW. Additionally, the transmitter 250 may receive the transmitted modulated signal TMS from the mixer 244 in the active mode, and the resonator 100 may generate an electromagnetic wave EMW corresponding to the transmission signal TS provided from the transmitter 250 through the first and second transmission terminals TX1 and TX2. For example, the transmitter 250 may, in the active mode, allow the first and second transmission terminals TX1 and TX2 to be coupled to the transmission power supply voltage TVDD through a pull-up load (e.g., a PMOS load) or to the ground voltage GND through a pull-down load (e.g., an NMOS load) based on the transmitted modulated signal TMS, such that the transmission signal TS can be provided to the resonator 102a through the first and second transmission terminals TX1 and TX2.

[0132] The processor 220 may provide a control signal CTL2 having a plurality of bits indicating the mode and operation of the NFC device 10a to the transmitter 250 based on the mode and operation of the NFC device 10a. Alternatively or additionally, the processor 220 may control the operation of the demodulator 241 by providing a control signal CTL4 to the demodulator 241.

[0133] Regulator 260 is coupled to a first power supply voltage VDD1 and can supply a transmission power supply voltage TVDD to transmitter 250. Regulator 260 can be implemented by a low dropout (LDO) regulator and can adjust the level of the transmission power supply voltage TVDD in response to a control signal CTL1 from processor 220.

[0134] In the active mode, processor 220 provides a control signal CTL2 to enable modulator 242 and transmits a request command through transmitter 250. Processor 220 provides a control signal CTL4 to enable demodulator 241, and demodulator 241 can wait for a response to the request command from the NFC tag during a predetermined (or, alternatively, variable) time interval. When a response to the request command is received during the predetermined time interval, NFC device 10a initiates data transmission / reception with the NFC tag. When a response to the request command is not received during the predetermined time interval, processor 220 provides control signals CTL2 and CTL4 to disable modulator 242 and demodulator 241, respectively, and provides control signals CTL1 and CTL3 to regulator 260 and frequency detector 400, respectively, to perform the above-described frequency detection operation.

[0135] When performing a signal reception operation in the card mode, second demodulator 281 generates second received data RD2 by demodulating a signal supplied from resonator 100 through first and second power terminals L1 and L2 to provide second received data RD2 to processor 220. Processor 220 can decode the second received data RD2 and can store some or all of the second received data RD2 in memory 230.

[0136] When performing a signal transmission operation in the card mode, processor 220 can read out output data from memory 230 and can encode the output data to provide second transmission data TD2 to second modulator 283, and second modulator 283 modulates the second transmission data TD2 to provide a modulated signal to first and second power terminals L1 and L2.

[0137] As described above, in the measurement mode for detecting the resonance frequency, transmitter 300 can generate a sense voltage signal VS at resonator 100. Regarding a plurality of measurement periods or during which each measurement period includes an on period and an off period, transmitter 300 can be enabled during the on period to output an RF signal to resonator 100 and can be disabled during the off period to generate the sense voltage signal VS. For example, the sense voltage signal VS can correspond to the voltage across capacitor C1, i.e., the voltage between measurement nodes NM1 and NM2.

[0138] The frequency detector 400 can be coupled to the resonator 100 through the first and second power terminals L1 and L2. As described above, the frequency detector 400 can detect the resonance frequency fr of the resonator 100 based on the sensed voltage signal VS.

[0139] Figure 15 is a diagram for describing the frequency characteristics of the resonator included in the NFC device. In Figure 15 the first curve A represents the frequency characteristics of the resonator 100.

[0140] Reference Figure 2 and Figure 15 , the resonator 100 can have longitudinal frequency characteristics that have a center at the carrier frequency fc. The resonator 100 can have a maximum gain MAX1 at the carrier frequency fc and can have a first bandwidth BW1, where the first frequency f1 and the second frequency f2 are used as the cutoff frequencies. The Q factor of the resonator 100 can have a value obtained by dividing the carrier frequency fc by the first bandwidth BW1.

[0141] Since the NFC chip 200 maintains the Q factor of the resonator 100 in the reader mode, when the signal transmission operation is performed in the card mode, the resonator 100 can have the frequency characteristics as shown in the first curve A.

[0142] If the frequency characteristics of the resonator 100 do not change when the signal reception operation is performed in the card mode, then as Figure 15 shown, the resonator 100 filters high-speed signals having a high frequency fu (e.g., a high frequency of 848 Kbps or higher) that is equal to or higher than the second frequency f2, so the NFC chip 200 generally may not demodulate the input data provided from an external device. Thus, the NFC device 10 may not perform high-speed communication.

[0143] When the size of the antenna included in the resonator 100 becomes small, the bandwidth BW1 of the resonator 100 can decrease, and the intensity of the EMW received from the external device becomes weak, so the available communication speed of the NFC device 10 may be further limited.

[0144] As will be described below, when the signal reception operation is performed in the card mode, the NFC chip 200 included in the NFC device 10 can decrease the Q factor of the resonator 100. For example, when the signal reception operation is performed in the card mode, the NFC chip 200 decreases the gain of the resonator 100 by connecting the terminal connected to the resonator 100 to the ground voltage GND via a pull-down load, so the resonator 100 can have as Figure 15The frequency characteristics shown in the second curve B at this time. At this time, the resonator 100 may have a maximum gain MAX2 at the carrier frequency fc and may have a second bandwidth BW2, where the third frequency f3 and the fourth frequency f4 are used as cutoff frequencies. Since the Q factor of the resonator 100 may have a value obtained by dividing the carrier frequency fc by the second bandwidth BW2, the Q factor of the resonator 100 decreases.

[0145] In this case, even when the resonator 100 receives a high-speed signal having a high frequency fu (e.g., a high frequency of 848 Kbps or higher) equal to or higher than the second frequency f2, the high-speed signal can be normally received without being filtered. Thus, the available communication speed of the NFC device 10 can be increased.

[0146] Meanwhile, since the load modulation characteristic decreases when the gain of the resonator 100 decreases during the signal transmission operation as described above, when performing the signal transmission operation, the NFC chip 200 disconnects the terminal connected to the resonator 100 from the ground voltage GND, so that the Q factor of the resonator 100 can be maintained.

[0147] Figure 16 is a diagram illustrating an exemplary embodiment of a transmitter included in an NFC device implemented according to some exemplary embodiments, and Figure 17 is for describing Figure 16 the operation of the transmitter.

[0148] Referring to Figure 16 , the transmitter 250a may include first 1-1 to first 1-n pull-up transistors (e.g., PMOS transistors) MP0-1, MP0-2,..., and MP0-n, second 2-1 to second 2-n pull-up transistors (e.g., PMOS transistors) MP1-1, MP1-2,..., and MP1-n, first 1-1 to first 1-n pull-down transistors (e.g., NMOS transistors) MN0-1, MN0-2,..., and MN0-n, second 2-1 to second 2-n pull-down transistors (e.g., NMOS transistors) MN1-, MN1-2,..., and MN1-n, and a driving unit 253.

[0149] The first 1-1 to first 1-n pull-up transistors MP0-1, MP0-2,..., and MP0-n and the second 2-1 to second 2-n pull-up transistors MP1-1, MP1-2,..., and MP1-n may be PMOS transistors, and the first 1-1 to first 1-n pull-down transistors MN0-, MN0-2,..., and MN0-n and the second 2-1 to second 2-n pull-down transistors MN1-1, MN1-2,..., and MN1-n may be NMOS transistors; however, the exemplary embodiments are not limited thereto.

[0150] The 1-1st to 1-nth pull-up transistors MP0-1, MP0-2, ..., and MP0-n can be connected in parallel between the supply voltage VDD and the first transmission terminal TX1, and the 1-1st to 1-nth pull-down transistors MN0-1, MN0-2, ..., and MN0-n can be connected in parallel between the first transmission terminal TX1 and the ground voltage GND.

[0151] The 2-1st to 2-nth pull-up transistors MP1-1, MP1-2, ..., and MP1-n can be connected in parallel between the supply voltage VDD and the second transmission terminal TX2, and the 2-1st to 2-nth pull-down transistors MN1-1, MN1-2, ..., and MN1-n can be connected in parallel between the second transmission terminal TX2 and the ground voltage GND.

[0152] The driving unit 253 can drive the 1-1st to 1-nth pull-up transistors MP0-1, MP0-2, ..., and MP0-n respectively through the 1-1st to 1-nth pull-up driving signals UDS0-1, UDS0-2, ..., and UDS0-n, drive the 1-1st to 1-nth pull-down transistors MN0-1, MN0-2, ..., and MN0-n respectively through the 1-1st to 1-nth pull-down driving signals DDS0-1, DDS0-2, ..., and DDS0-n, drive the 2-1st to 2-nth pull-up transistors MP1-1, MP1-2, ..., and MP1-n respectively through the 2-1st to 2-nth pull-up driving signals UDS1-1, UDS1-2, ..., and UDS1-n, and drive the 2-1st to 2-nth pull-down transistors MN1-1, MN1-2, ..., and MN1-n respectively through the 2-1st to 2-nth pull-down driving signals DDS1-1, DDS1-2, ..., and DDS1-n.

[0153] The driving unit 253 can determine whether the NFC chip 200d is in the card mode or the reader mode, and when the mode is the card mode, can determine the signal reception operation or the signal transmission operation based on the mode signal MD supplied from the CPU 240.

[0154] In the reader mode, the driving unit 253 can turn on the 1-1st to 1-nth pull-up transistors MP0-1, MP0-2, ..., and MP0-n or the 1-1st to 1-nth pull-down transistors MN0-1, MN0-2, ..., and MN0-n based on the transmission modulation signal TMS, and can turn on the 2-1st to 2-nth pull-up transistors MP1-1, MP1-2, ..., and MP1-n or the 2-1st to 2-nth pull-down transistors MN1-, MN1-2, ..., and MN1-n.

[0155] The drive unit 253 may receive a pull-down control signal FDC generated by the processor 220 in Figure 14 based on the detection result of the resonance frequency fr.

[0156] In the card mode, the drive unit 253 may select k pull-down transistors from among the first 1-1 to 1-n pull-down transistors MN0-1, MN0-2, ..., and MN0-n and the second 1-1 to 2-n pull-down transistors MN1-1, MN1-2, ..., and MN1-n based on the pull-down control signal FDC. For example, the drive unit 253 may select the first 1-1 to 1-k pull-down transistors MN0-1, MN0-2, ..., and MN0-k and the second 1-1 to 2-k pull-down transistors MN1-1, MN1-2, ..., and MN1-k, where k is a positive integer equal to or less than n.

[0157] In the card mode, the drive unit 253 generates the first 1-1 to 1-n upper pull drive signals UDS0-1, UDS0-2, ..., and UDS0-n and the second 1-1 to 2-n upper pull drive signals UDS1-1, UDS1-2, ..., and UDS1-2 having a logic high level, so that the drive unit 253 can turn off the first 1-1 to 1-n upper pull transistors MP0-1, MP0-2, ..., and MP0-n and the second 1-1 to 2-n upper pull transistors MP1-1, MP1-2, ..., and MP1-n. In addition, as Figure 17 shown, the drive unit 253 generates the first 1-(k + 1) to 1-n pull-down drive signals DDS0-(k + 1), ..., and DDS0-n and the second 1-(k + 1) to 2-n pull-down drive signals DDS1-(k + 1), ..., and DDS1-n having a logic low level, so that the drive unit 253 can turn off the non-selected first 1-(k + 1) to 1-n pull-down transistors MN0-(k + 1), ..., and MN0-n and the second 1-(k + 1) to 2-n pull-down transistors MN1-(k + 1), ..., and MN1-n.

[0158] In addition, as Figure 17As shown, when performing a signal reception operation RX in card mode, the driving unit 253 can sequentially turn on the first to k-th pull-down transistors MN0-1, MN0-2,..., and MN0-k and the first to k-th pull-down transistors MN1-1, MN1-2,..., and MN1-k at a first time interval Ta by sequentially enabling the first to k-th pull-down driving signals DDS0-1, DDS0-2,..., and DDS0-k and the first to k-th pull-down driving signals DDS1-1, DDS1-2,..., and DDS1-k at the first time interval Ta.

[0159] Furthermore, as Figure 17 shown, when performing a signal transmission operation TX in card mode, the driving unit 253 can sequentially turn off the first to k-th pull-down transistors MN0-1, MN0-2,..., and MN0-k and the first to k-th pull-down transistors MN1-1, MN1-2,..., and MN1-k at a first time interval Ta by sequentially disabling the first to k-th pull-down driving signals DDS0-1, DDS0-2,..., and DDS0-k and the first to k-th pull-down driving signals DDS1-1, DDS1-2,..., and DDS1-k at the first time interval Ta.

[0160] As described above, the transmitter 250a drives the first to n-th pull-up transistors MP0-1, MP0-2,..., and MP0-n, the first to n-th pull-up transistors MP1-1, MP1-2,..., and MP1-n, the first to n-th pull-down transistors MN0-1, MN0-2,..., and MN0-n, and the first to n-th pull-down transistors MN1-1, MN1-2,..., and MN1-n based on the transmission modulation signal TMS in reader mode to perform a normal operation to provide the transmission signal TS to the resonator 100. Additionally, when performing a signal reception operation in card mode, the transmitter 250a connects the first transmission terminal TX1 and the second transmission terminal TX2 to the ground voltage GND through the first to k-th pull-down transistors MN0-1, MN0-2,..., and MN0-k and the first to k-th pull-down transistors MN1-1, MN1-2,..., and MN1-k, thereby reducing the Q factor of the resonator 100. Additionally, when performing a signal reception operation in card mode based on the pull-down control signal FDC, the transmitter 250a can control the degree of reduction of the Q factor of the resonator 100 by adjusting the number (k) of the turned-on pull-down transistors.

[0161] When the transmitter 250a turns on or off the first 1-1 to 1-k pull-down transistors MN0-1, MN0-2, ..., and MN0-k and the second 2-1 to 2-k pull-down transistors MN1-1, MN1-2, ..., and MN1-k simultaneously in the card mode, unless otherwise addressed, the amplitudes of the voltages in the first power terminal L1 and the second power terminal L2 may instantaneously swing, resulting in possible errors in data communication.

[0162] As described above, when performing a signal reception operation in the card mode, the transmitter 250a sequentially turns on the first 1-1 to 1-k pull-down transistors MN0-1, MN0-2, ..., and MN0-k and the second 2-1 to 2-k pull-down transistors MN1-1, MN1-2, ..., and MN1-k at a first time interval Ta, and when performing a signal transmission operation in the card mode, the transmitter 250a sequentially turns off the first 1-1 to 1-k pull-down transistors MN0-1, MN0-2, ..., and MN0-k and the second 2-1 to 2-k pull-down transistors MN1-1, MN1-2, ..., and MN1-k at the first time interval Ta, thereby preventing the voltages of the first power terminal L1 and the second power terminal L2 from swinging when changing the Q factor of the resonator 100.

[0163] Therefore, by setting an appropriate pull-down amount corresponding to the detected resonance frequency fr, the load modulation amplitude (LMA) can be increased, and the performance of the NFC device can be improved.

[0164] Figure 18 FIG. is a diagram illustrating an NFC device according to some example embodiments.

[0165] Reference Figure 18 , the NFC device 11 includes a resonator 101 and an NFC chip 201. The NFC chip 201 includes a transmitter Tx300, a frequency detector FDET 400, and a controller CON 501. Figure 18 The NFC device 11 of Figure 2 is substantially the same as the NFC device 10 of

[0166] The controller 501 can generate a frequency control signal FCON based on the detected resonance frequency fr as described above. The resonator 101 can have a configuration capable of changing the impedance of the resonator 10. For example, as Figure 18 illustrated, the capacitor C1 can be implemented as a variable capacitor. The frequency control signal FCON can be provided to the resonator 101 through a control terminal TC. The resonance frequency fr can be adjusted to be suitable for various operating environments by adjusting the capacitance of the capacitor C1 based on the frequency control signal FCON.

[0167] Figure 19 and Figure 20 is a diagram showing a test system according to some example embodiments.

[0168] Referring Figure 19 , the test system 700 may include a test device 710 and a device under test (DUT). The DUT may be or may include an NFC device having a resonator RSU and an NFC chip.

[0169] Figure 19 Illustrates some example embodiments in which the frequency detector FDET described above is included in the test device. In this case, a sensing voltage signal VS may be provided to the test device 710 external to the DUT (i.e., the NFC device), and the frequency detector FDET included in the test device 710 may be used to detect the resonant frequency fr based on the sensing voltage signal VS.

[0170] Figure 20 Illustrates some example embodiments in which the frequency detector FDET is included in the DUT (e.g., an NFC device). In this case, a control signal for detecting the resonant frequency fr may be provided to a plurality of DUTs simultaneously, and parallel testing may be effectively performed.

[0171] Figure 21 is a block diagram showing an electronic device according to some example embodiments.

[0172] Referring Figure 21 , the electronic device 1000 includes an application processor (AP) 1110, an NFC device 1200, a memory device 1120, a user interface 1130, and a power supply 1140.

[0173] The application processor 1110 may control the overall operation of the electronic device 1000. The memory device 1120 may store data for the operation of the electronic device 1000. The NFC device 1200 may provide output data stored in the memory device 1120 to an external device via NFC and store input data received from the external device via NFC in the memory device 1120.

[0174] The NFC device 1200 includes a resonator 1210 and an NFC chip 1220. As described above, the NFC device 1200 may effectively detect the resonant frequency using the frequency detector FDET.

[0175] The user interface 1130 may include at least one input device such as a keypad and / or a touch screen, and at least one output device such as a speaker and / or a display device. The power supply 1140 may supply a power voltage to the electronic device 1000.

[0176] As described above, an NFC device and / or method according to some example embodiments may accurately or more accurately detect a resonance frequency by measuring the resonance frequency during a plurality of measurement periods. The resonance frequency may be more accurately detected by converting a sensed voltage signal into a clock signal and counting the number of clocks of the clock signal.

[0177] An NFC device and / or method according to some example embodiments may effectively detect a resonance frequency by generating a sensed voltage signal by using a transmitter established in the NFC device.

[0178] An NFC device and / or method according to some example embodiments may effectively detect a resonance frequency without an external device by implementing a frequency detector as an on-chip component.

[0179] Each of, or at least some of, the elements described above may include a processing circuit, such as hardware including logic circuits; a hardware / software combination such as a processor executing software; or a combination thereof. For example, the controller 500, the transmitter 300, the frequency detector 400, the clock extractor 410, the counter 420, the frequency generator 430, the driving unit 253, the processor 220, the memory 230, the first demodulator 241, the first modulator 242, the oscillator 243, the mixer 244, the demultiplexer 245, the transmitter 250, the regulator 260, the rectifier 271, the regulator 273, the power switch PSW, the second demodulator 281, the second modulator 283, and so on may include a processing circuit, such as hardware including logic circuits; a hardware / software combination such as a processor executing software; or a combination thereof. For example, the processing circuit more specifically includes, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a system on chip (SoC), a programmable logic unit, a microprocessor, an application specific integrated circuit (ASIC), and so on.

[0180] The inventive concept may be applied to an NFC device and / or a system including an NFC device. For example, the inventive concept may be applied to a system, such as at least one of a mobile phone, a smartphone, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a video camera, a personal computer (PC), a server computer, a workstation, a laptop computer, a digital TV, a set-top box, a portable game console, a navigation system, a wearable device, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, an e-book, a virtual reality (VR) device, an augmented reality (AR) device, and so on.

[0181] The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although some example embodiments have been described, many modifications in the example embodiments are possible for those skilled in the art without materially departing from the inventive concept.

Claims

1. A near field communication (NFC) device, comprising: A resonator, including an antenna and a matching circuit; A transmitter configured to generate a sense voltage signal at the resonator during a plurality of measurement periods, each of the plurality of measurement periods including an on period and an off period, the transmitter being enabled during the on period to output a radio frequency (RF) signal to the resonator and being prohibited from outputting an RF signal to the resonator during the off period; And A frequency detector configured to detect a resonance frequency of the resonator based on the sense voltage signal and based on a formula, Wherein the frequency detector includes: A clock extractor configured to generate a clock signal that toggles according to an oscillation of the sense voltage signal; A counter configured to generate a clock count by counting clock counts of the clock signal; and A frequency generator configured to provide the resonance frequency based on the clock count, Wherein the frequency detector is configured to determine the resonance frequency based on a formula, and the formula is fr = (CNT * ton) / (N * toff 2 ) Where fr corresponds to the resonance frequency, CNT corresponds to the clock count, N corresponds to the number of the plurality of measurement periods, ton corresponds to a time interval of each on period, and toff corresponds to a time interval of each off period.

2. The NFC device according to claim 1, wherein, The transmitter is configured to generate the sense voltage signal, the sense voltage signal oscillating at a transmission frequency during the on period based on the RF signal and oscillating at the resonance frequency during the off period based on an induced electromotive force induced by the RF signal in the resonator.

3. The NFC device according to claim 1, wherein The frequency detector is configured to convert the sense voltage signal into a clock signal and count clock counts of the clock signal.

4. The NFC device according to claim 1, wherein, The transmitter is configured to generate the sense voltage signal at the resonator based on an RF enable signal, the RF enable signal being activated during the on period and deactivated during the off period.

5. The NFC device according to claim 1, further comprising: A count control circuit configured to generate a count enable signal, Among them, The counter being configured to generate the clock count by counting clock counts of the clock signal during an activation time interval of the count enable signal.

6. The NFC device according to claim 5, wherein, The count control circuit is configured to generate a count enable signal that is activated during the plurality of measurement periods independently of the on period and the off period.

7. The NFC device according to claim 5, wherein, The count control circuit is configured to generate the count enable signal that is activated during the off period and deactivated during the on period.

8. The NFC device according to claim 5, wherein, The count control circuit includes: An inverter configured to generate an inverted RF enable signal by inverting the RF enable signal, the RF enable signal being activated during the on period and deactivated during the off period; And An AND logic gate configured to generate a count enable signal by performing an AND logic operation on a measurement enable signal and the inverted RF enable signal, wherein the measurement enable signal is activated during the plurality of measurement periods.

9. The NFC device according to claim 5, wherein, The counting control circuit is configured to generate a counting enable signal, and the counting enable signal is activated in a time period after a delay time from the start time point of the off period and deactivated at the start time point of the on period.

10. The NFC device according to claim 5, wherein, The counting control circuit includes: a delay circuit configured to generate a first signal by delaying an RF enable signal, where the RF enable signal is activated during the on period and deactivated during the off period; an OR logic gate configured to generate a second signal by performing an OR logic operation on the RF enable signal and the first signal; an inverter configured to generate a third signal by inverting the second signal; and an AND logic gate configured to generate the counting enable signal by performing an AND logic operation on a measurement enable signal and the third signal, where the measurement enable signal is activated during the plurality of measurement periods.

11. The NFC device according to claim 5, wherein, The frequency detector is configured to determine the resonant frequency based on a mapping table indicating a mapping between a plurality of values indicating the clock count and a plurality of values of the resonant frequency.

12. A method for detecting a resonant frequency of a Near Field Communication (NFC) device, the method including: During a plurality of measurement periods, where each of the plurality of measurement periods includes an on period and an off period, generating a sensing voltage signal at the resonator by enabling a transmitter included in the NFC device to output a Radio Frequency (RF) signal to the resonator included in the NFC device during the on period and disabling the transmitter during the off period; and Detecting the resonant frequency of the resonator based on the sensing voltage signal and based on a formula, Among them, Generating the resonant frequency includes: Generating a clock signal that toggles according to the oscillation of the sensing voltage signal; Generating a clock count by counting the number of clocks of the clock signal; and Providing the resonant frequency based on the clock count, where the formula is fr = (CNT * ton) / (N * toff 2 ) where fr corresponds to the resonant frequency, CNT corresponds to the clock count, N corresponds to the number of the plurality of measurement periods, ton corresponds to the time interval of each on period, and toff corresponds to the time interval of each off period.

13. The method according to claim 12, wherein, The NFC device uses a frequency detector included in the NFC device to detect the resonant frequency based on the sensing voltage signal.

14. The method according to claim 12, wherein, The NFC device provides the sensing voltage signal to an external device, and the external device uses a frequency detector included in the external device to detect the resonant frequency based on the sensing voltage signal.

15. The method according to claim 12, wherein, The sensing voltage signal oscillates at a transmission frequency during the on period based on the RF signal, and oscillates at the resonant frequency based on the electromotive force induced by the RF signal in the resonator.

16. A method for detecting a resonant frequency of a Near Field Communication (NFC) device, the method including: During a plurality of measurement periods, where each measurement period includes an on period and an off period, generating an RF enable signal that is activated during the on period and deactivated during the off period; Generate a sensing voltage signal based on the RF enabling signal by enabling a transmitter included in the NFC device during the on period to output a radio frequency (RF) signal to a resonator included in the NFC device and disabling the transmitter during the off period to generate the sensing voltage signal at the resonator; Generate a clock signal that toggles according to the oscillation of the sensing voltage signal; Generate a clock count by counting the number of clocks of the clock signal during an active time interval of a count enabling signal; and Provide the resonance frequency based on the clock count and based on a formula, where the formula is fr = (CNT * ton) / (N * toff 2 ) where fr corresponds to the resonance frequency, CNT corresponds to the clock count, N corresponds to the number of the plurality of measurement periods, ton corresponds to the time interval of each on period, and toff corresponds to the time interval of each off period.

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