Near field communications device

A near field communications (NFC) device includes a receiving module and a transmitting module. The receiving module includes a receiver receiving an analog signal that includes a carrier signal and data, an analog-to-digital converter converting the analog signal to a digital signal, and a filter filtering the digital signal. The transmitting module includes a direct current-direct current (DC-DC) converter having an operating frequency belonging to a stop band of the filter, and a transmitter receiving power from the DC-DC converter and receiving a system clock signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to Korean Patent Application No. 10-2017-0046739, filed on Apr. 1, 2017 and Korean Patent Application. No. 10-2017-0023486, filed on Feb. 22, 2017 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entireties.

BACKGROUND

The present inventive concept relates to a near field communication (NFC) device.

2. Description of Related Art

Near field communication (NFC) technologies are communications technologies that may enable data exchange within a short distance, using a signal having a specific frequency bandwidth, and have been applied in various fields, due to advantages such as a high level of security and the like. In recent years, NFC devices providing NFC functions have been mounted in various types of electronic devices, and mobile devices may provide the user with electronic payment functions used in transportation cards, credit cards, and coupons, and data exchange functions using the NFC function.

SUMMARY

An aspect of the present inventive concept may provide a near field communication (NFC) device having improved communications performance and power consumption efficiency.

According to an aspect of the present inventive concept, an NFC device may include a receiving module and a transmitting module. The receiving module includes a receiver receiving an analog signal that includes a carrier signal and data, an analog-to-digital converter converting the analog signal to a digital signal, and a filter filtering the digital signal. The transmitting module includes a direct current-direct current (DC-DC) converter having an operating frequency belonging to a stop band of the filter, and a transmitter receiving power from the DC-DC converter to operate and receiving a system clock signal to transmit the carrier signal.

According to an aspect of the present inventive concept, an NFC device may include a receiver receiving an analog signal including a carrier signal and data, an analog-to-digital converter converting the analog signal into a digital signal, and a digital filter filtering the digital signal in a predetermined stop band. The stop band includes a frequency of a signal generated by dividing the carrier signal, and harmonic components of the frequency.

According to an aspect of the present inventive concept, an NFC device may include a clock generating unit generating a system clock signal, a transmitter amplifying the system clock signal to generate a carrier signal required for NFC, a DC-DC converter supplying a power supply voltage required for an operation of the transmitter, and a DC-DC control unit determining a control method of the DC-DC converter depending on whether an NFC tag receiving the carrier signal is present.

DETAILED DESCRIPTION

Hereinafter, the example embodiments of the present inventive concept will be described as follows with reference to the attached drawings.

FIG. 1is a view of an electronic device including a near field communication (NFC) device according to an example embodiment.

Referring toFIG. 1, the electronic device10according to an example embodiment may include a housing11, a display12, a camera unit13, and an input unit14. The electronic device10is illustrated as a mobile device, such as a smartphone, a tablet personal computer (PC), or a laptop PC. However, the NFC device according to an example embodiment may also be applied, to other various devices, such as a desktop PC, a home television, a set-top box, a refrigerator, and a washing machine.

The NFC device included in the electronic device10may communicate with an NFC tag20, using a carrier signal in a particular frequency band. A carrier signal that the NFC device transmits to the NFC tag20may not include data. The NFC tag20may generate power required for operations thereof, using the carrier signal received from the NFC device.

Further, the NFC tag20may include predetermined data in the carrier signal, and may transmit the carrier signal to the NFC device. For example, the NFC device may transmit the carrier signal without data to the NFC tag20, and receive the carrier signal with the data from the NFC tag20. In an example embodiment, a frequency of the carrier signal used in communications between the NFC device and the NFC tag20may be 13.56 MHz. In order to increase performance of the NFC device and the NFC tag20, strength of the carrier signal output by the NFC device may be required to be increased. The NFC device may include a power amplifier (PA) and a DC-DC converter supplying a power supply voltage to the PA, in order to increase the strength of the carrier signal.

The DC-DC converter may operate according to a predetermined, switching frequency, and may include at least one switch device repeatedly turned on or off, according to the switching frequency. In an example embodiment, the switching frequency may be a frequency of a signal for controlling the at least one switch device. The power supply voltage that the DC-DC converter supplies to the power amplifier may include a ripple component generated by operations of the at least one switch device.

In an example embodiment, the power supply voltage that the DC-DC converter supplies to the power amplifier may be converted into a signal having the same frequency as that of the carrier signal, by operations of the power amplifier. Thus, the ripple component, included in the power supply voltage supplied by the DC-DC converter, may be reflected in the carrier signal output by the power amplifier, and may be transmitted to the NFC tag20. The NFC tag20may include data in the carrier signal received from the NFC device, and may transmit the carrier signal including the data to the NFC device. Thus, the ripple component may also be included in the signal that the NFC device receives from the NFC tag20. The ripple component may act as a noise component in a process of demodulating the signal received by the NFC device and extracting the data, and may cause a reduction in communications performance between the electronic device10and the NFC tag20.

According to various example embodiments, the DC-DC converter may be applied to the NFC device, thus significantly improving communications performance. Furthermore, a size and power consumption of the NFC device may be reduced, and a noise component generated by the DC-DC converter may be removed effectively.

FIG. 2is a schematic block diagram of an NFC device according to an example embodiment.FIG. 3is a schematic block diagram of a filter that may be included in an NFC device according to an example embodiment.

Referring toFIG. 2, an NFC device100according to an example embodiment may include a clock generating unit101, a coil unit102, a transmitting module110, and a receiving module120. The transmitting module110may include a DC-DC converter111and a transmitter112. The receiving module120may include a receiver121, an analog-to-digital converter (ADC)122, and a filter123.

The clock generating unit101may generate a system clock signal having a predetermined frequency. In an example embodiment, a frequency of the system clock signal may be 13.56 MHz, and the system clock signal may be input to each of the DC-DC converter111and the transmitter112. The transmitter112may amplify the system clock signal to generate a transmission signal ST. In an example embodiment, a frequency of the transmission signal STmay be equal to that of the system clock signal, and a magnitude of the transmission signal STmay be greater than that of the system clock signal. The transmission signal STmay be transmitted to an NFC tag contiguous to the NFC device100through the coil unit102.

The transmitter112may receive a power supply voltage required for an operation of amplifying the magnitude of the transmission signal STfrom the DC-DC converter111. In an example embodiment; the DC-DC converter111may be a boost converter including at least one switch device, and may change an output of the DC-DC converter111by controlling the at least one switch device. The at least one switch device may be controlled by a control signal having a predetermined frequency, and an operating frequency of the DC-DC converter111may be determined by the frequency of the control signal. The operating frequency of the DC-DC converter111may be equal to the frequency of the control signal, and may be lower than the frequency of the system clock signal. In an example embodiment, when the frequency of the system clock signal is 13.56 MHz, the operating frequency may have a value obtained by dividing the frequency of the system clock signal by an integer, such as 3.39 MHz or 1.695 MHz.

The coil unit102may transmit, to the receiver121, a reception signal SRwhich the NFC tag contiguous to the NFC device100transmits. In an example embodiment, the receiver121may include an attenuator, a mixer, and an amplifier, and the reception signal SR, having been subjected to a signal processing process in the receiver121, may be converted into a digital signal by the analog-to-digital converter122. An output terminal of the analog-to-digital converter122may be connected to the filter123, and the filter123may be a digital filter filtering the digital signal. In an example embodiment, the filter123may remove a noise component generated by an operation of the DC-DC converter111and reflected in the transmission signal STand the reception signal SR.

In an example embodiment, the filter123may have a predetermined stop band in a frequency domain, and may remove a signal in the predetermined stop band. Referring toFIG. 3, illustrating a configuration of the filter123, the filter123may be designed as a finite impulse response (FIR) filter, and may include a delay unit210, a multiplication unit220, and an addition unit230. By designing the filter123as the FIR filter, the filter123may operate as a notch filter, selectively removing only a signal included in the stop band.

In an example embodiment, a notch frequency determining the stop band of the filter123and the operating frequency of the DC-DC converter111may be substantially the same as each other. For example, the operating frequency of the DC-DC converter111may be included in the stop band of the filter123. Thus, the noise component generated by the operation of the DC-DC converter111and included in the transmission signal STand the reception signal SRmay be effectively removed by the filter123, resulting in an improvement in a signal-to-noise ratio (SNR) of the NFC device100.

FIG. 4is a schematic block, diagram of an NFC device300according to an example embodiment.FIGS. 5 through 13are views illustrating operations of an NFC device according to an example embodiment. Hereinafter, operations of the NFC device according to an example embodiment will be described with reference to the schematic block diagram ofFIG. 4and the views ofFIGS. 5 through 13.

Referring toFIG. 4, the NFC device300according to an example embodiment may include a clock generating unit301, a coil unit302, a transmitting module310, and a receiving module320. The transmitting module310may include a divider311, a DC-DC control unit312, a DC-DC converter313, and a power amplifier (PA)314. The receiving module320may include a matching network321, an attenuator322, a mixer323, a first filter324, a variable-gain amplifier (VGA)325, an analog-to-digital converter (ADC)326, and a second filter327. Configurations of the transmitting module310and the receiving module320are not limited to those in the example embodiment illustrated inFIG. 4, and may be modified, in various ways.

The clock generating unit301may generate a system clock signal. In an example embodiment, a frequency of the system clock signal may be 13.56 MHz, an NFC communications frequency, or may be an integer multiple thereof. The system clock signal may be input to the divider311and the PA314of the transmitting module310.

The power amplifier314may amplify the system clock signal to generate a transmission signal STand the transmission signal STmay have the same frequency as that of the system clock signal. In an example embodiment, a magnitude of the transmission signal STmay be determined by a power supply voltage that the DC-DC converter313supplies to the power amplifier314. The DC-DC control unit312may determine the magnitude of the transmission signal STby adjusting the power supply voltage that the DC-DC converter313supplies to the power amplifier314.

The divider311may divide the system clock signal to generate a divided signal having a frequency different from that of the system clock signal. In an example embodiment, the divided signal may have a frequency obtained by dividing the frequency of the system clock signal N times, where N is an integer. For example, when the frequency of the system clock signal is 13.56 MHz, the frequency of the divided signal may have a value such as 1.695 MHz or 3.39 MHz.

The DC-DC control unit312may generate a control signal for adjusting an output of the DC-DC converter313, using the divided signal. The DC-DC control unit312may adjust a magnitude of the power supply voltage that the DC-DC converter313supplies to the power amplifier314by changing a duty ratio or frequency of the control signal. In an example embodiment, the DC-DC control unit312may change the duty ratio of the control signal when load is present in the NFC device300, and may change the frequency of the control signal when no load is present in the NFC device300, adjusting the magnitude of the power supply voltage output by the DC-DC converter313. The DC-DC control unit312may determine whether load is present in the NFC device300, based on a load current of the NFC device300.

Under the condition that no load is present in the NFC device300, the DC-DC control unit312may lower the frequency of the control signal, thus the operating frequency of the DC-DC converter313may be decreased. Thus, power consumption of the DC-DC converter313may be reduced under the condition that no load is present in the NFC device300, and the overall power consumption of the NFC device300may be managed efficiently.

Under the condition that load is present in the NFC device300, the DC-DC control unit312may select a frequency of the control signal appropriately. In an example embodiment, the DC-DC control unit312may select the frequency of the control signal as a value included in a stop band of the second filter327included in the receiving module320. As an example, when the second filter327is a notch filter, the DC-DC control unit312may select the frequency of the control signal as a value substantially the same as a notch frequency of the second filter327or as harmonic components thereof. For example, when the notch frequency of the second filter327is 3.39 MHz and the frequency of the divided signal output by the divider311is 1.695 MHz, the DC-DC control unit312may generate a control signal having a frequency of 3.39 MHz, using the divided signal. By selecting the frequency of the control signal as the value included in the stop band of the second filter327, the second filter327may effectively remove a noise component included in the transmission signal by an operation of the DC-DC converter313.

The reception signal SRmay include a carrier signal transmitted by an NFC tag, and data superimposed on the carrier signal, and the receiving module320may convert the data included in the reception signal SRinto a digital domain. In an example embodiment, the reception signal SR, transmitted by the NFC tag contiguous to the NFC device300, may include data superimposed on the carrier signal in a sub-carrier frequency band. The attenuator322may appropriately reduce an amplitude of the reception signal SRand transmit the reception signal SRto the mixer323, and the mixer323may convert a frequency of the reception signal SR. In an example embodiment, the mixer323may down-convert the reception signal SRby a frequency of the carrier signal.

The first filter324, as an analog filter, may be a high-pass filter or a band-pass filter, or may also include both the high-pass filter and the band-pass filter. The first filter324may remove a high-frequency noise component. As an example, the first filter324may remove a signal from a remaining frequency bandwidth, except for an NFC bandwidth.

An output of the first filter324may be input to the variable-gain amplifier325. The variable-gain amplifier325may amplify an input signal by a predetermined gain, and may transmit the amplified input signal to the analog-to-digital converter326. In an example embodiment, a gain of the variable-gain amplifier325and an attenuation amount of the attenuator322may be appropriately selected, such that an output of the analog-to-digital converter326may not be saturated by the noise component included in the reception signal SR.

The second filter327may be a digital filter connected to an output terminal of the ADC326, and may include a notch filter. For example, the second filter327may selectively remove a signal in a stop band, defined by a notch frequency and harmonic components thereof.

In an example embodiment, the notch frequency of the second filter327may be a predetermined value, and the DC-DC control unit312may determine the frequency of the control signal, with reference to the notch frequency or the harmonic components of the second filter327. The frequency of the control signal generated by the DC-DC control unit312may be an operating frequency of the DC-DC converter313, and the noise component, generated at the operating frequency by the operation of the DC-DC converter313, may be present in the transmission signal STand the reception signal SR. In an example embodiment, the operating frequency may correspond to the notch frequency of the second filter327or to the harmonic components thereof, or may be included in the stop band of the second filter327. Thus, the noise component, included in the reception signal SRin an operating frequency band, may be removed by the second filter327.

In an example embodiment, the notch frequency of the second filter327may be a changeable value. When the notch frequency of the second filter327is changeable, the notch frequency may be determined in consideration of the operating frequency of the DC-DC converter313. Alternatively, the notch frequency may be selected such that the harmonic components of the notch frequency correspond to the operating frequency of the DC-DC converter313. In an alternative example embodiment, the notch frequency may be appropriately selected such that the operating frequency of the DC-DC converter313may be included in the stop band of the second filter327.

In addition, in an example embodiment, the frequency of the control signal adjusting the output of the DC-DC converter313, a frequency of the reception signal SRrequired for frequency conversion of the mixer323, a sampling frequency of the analog-to-digital converter326, and the notch frequency of the second filter327may be determined from the frequency of the system clock signal generated by the clock generating unit301. When the frequency of the system, clock signal varies, the variation in the frequency of the system clock signal may be reflected in both the transmitting module310and the receiving module320. Thus, the frequency variation of the system clock signal may be naturally offset in the transmitting module310and the receiving module320to prevent a reduction in filtering performance of the second filter327due to the frequency variation of the system clock signal, thus efficiently improving an signal-to-noise ratio of the NFC device300.

Hereinafter, characteristics of input and output signals of the primary components will be described with reference toFIGS. 4 and 5 through 13.

FIG. 5is a view illustrating a frequency spectrum of the power supply voltage that the DC-DC converter313supplies to the power amplifier314. Referring toFIG. 5, the power supply voltage may further include a noise component400generated at an operating frequency fDCDC, in addition to a direct current (DC) component having a frequency of 0. In an example embodiment, the power supply voltage may also further include a noise component generated by harmonic components of the operating frequency fDCDC, in addition to the noise component generated at the operating frequency fDCDCof the DC-DC converter313.

The power amplifier314may operate by the power supply voltage supplied by the DC-DC converter313. In a process of generating the transmission signal STby the power amplifier314, the noise component400included, in the power supply voltage may be converted in frequency by a carrier frequency fCof the transmission signal ST. Referring toFIG. 5, illustrating a frequency spectrum of the transmission signal ST, the transmission signal STmay include a first noise component410and a second noise component420that appear at a first frequency fC+fDCDCand a second frequency fC−fDCDCrespectively, in addition to a carrier signal CW having the carrier frequency fC.

FIG. 7is a view illustrating a frequency spectrum of the reception signal SRinput to the matching network321. In an example embodiment, the reception signal may have the same carrier frequency fCas the transmission signal SThas, and may include a first noise component410and a second noise component420that appear at a first frequency fC+fDCDCand a second frequency fC−fDCDC, respectively, as the transmission signal STincludes. For example, the first and second noise components410and420, generated by the DC-DC converter313and reflected in the transmission signal ST, may return to the receiving module320through the reception signal SR.

Unlike the transmission signal STthat includes no data, the reception signal SRmay include first NFC data510and second NFC data520. The first and second NFC data510and520may include the same information, may be superimposed on a carrier signal in a predetermined sub-carrier frequency band, and may be transmitted. In an example embodiment, a sub-carrier frequency may be lower than a switching frequency fDCDCof the DC-DC converter313, and may be a level of several hundred kHz.

The first and second NFC data510and520, transmitted on the sub-carrier frequency band, may have magnitudes less than those of the first and second noise components410and420that appear at the first and second frequencies fC+fDCDCand fC−fDCDC, respectively. In an example embodiment, the first and second noise components410and420may have magnitudes several to dozens of times greater than or equal to those of the first and second NFC data510and520.

The reception signal SRmay be down-converted by the carrier frequency fCin the mixer323, and the variable-gain amplifier325may adjust a magnitude of the down-converted reception signal SR. Referring toFIG. 8that illustrates an input of the second filter327as a frequency spectrum, NFC data500, at the input of the second filter327, may be present at a sub-carrier frequency fIF, and the noise component400, at the input of the second filter327, may be present at the operating frequency fDCDCof the DC-DC converter313.

As described above, the second filter327may have characteristics of the notch filter, selectively blocking a signal in a particular frequency band. WhenFIG. 8, illustrating an output of the mixer323as a frequency spectrum, is compared toFIG. 9, illustrating an output of the second filter327as a frequency spectrum, the noise component400may have been removed by the second filter327.

Referring toFIGS. 8 and 9, a notch frequency, a frequency at which a signal is blocked by a mask600of the second filter327, may be substantially the same as at least one of the operating frequency fDCDCand the harmonic components thereof. For example, the operating frequency fDCDCof the DC-DC converter313and the harmonic components thereof may be included in the stop band in which the second filter327may remove the signal. The stop band of the second filter327may include a plurality of frequency bands corresponding to the operating frequency fDCDCof the DC-DC converter313and the harmonic components thereof. Thus, the noise component400, appearing at the operating frequency fDCDCor in the harmonic components thereof, may be removed by the second filter327. In an example embodiment, the second filter327may be implemented as an FIR filter having impulse response characteristics in a finite interval.

Referring again toFIG. 9illustrating the output of the second filter327as the frequency spectrum, the noise component400of the operating frequency fDCDCor of the harmonic components thereof may be removed, and only the NFC data500may remain. This may be an effect obtained from design features that the operating frequency fDCDCof the DC-DC converter313and the harmonic components thereof may be included in the stop band of the second filter327. In an example embodiment, the signal-to-noise ratio of the NFC device300may be improved by substantially matching the operating frequency fDCDCof the DC-DC converter313included in the transmitting module310, with the notch frequency of the second filter327included in the receiving module320.

FIG. 10is a view illustrating a signal, input to the second filter327, as a frequency spectrum, when the operating frequency fDCDCof the DC-DC converter313is substantially equal to twice a notch frequency fnotchof the second filter327.FIG. 11is a view illustrating a signal, input to the second filter327, as a frequency spectrum, when the operating frequency fDCDCof the DC-DC converter313is substantially equal to three times the notch frequency fnotchof the second filter327. In the example embodiments illustrated inFIGS. 10 and 11, each of noise components430and440, generated by the DC-DC converter313, may be present at the operating frequency fDCDCof the DC-DC converter313. Referring to the mask600of the second filter327, the operating frequency fDCDCmay be included in the stop band of the second filter327. Thus, the noise components430and440present at the operating frequency fDCDCmay be effectively removed.

FIG. 12is a view illustrating an input of the second filter327as a frequency spectrum, when the operating frequency fDCDCof the DC-DC converter313is equal to the notch frequency fnotchof the second filter327and noise components450are present at the operating frequency fDCDCand in the harmonic components thereof.FIG. 13is a view illustrating an input of the second filter327as a frequency spectrum, when the operating frequency fDCDCof the DC-DC converter313is equal to twice the notch frequency fnotchof the second filter327and noise components460are present at the operating frequency fDCDCand in the harmonic components thereof. In each of the example embodiments illustrated inFIGS. 12 and 13, the operating frequency fDCDCand the harmonic components thereof may be included in a stop band defined by the notch frequency fnotchof the second filter327and the harmonic components thereof. Thus, the second filter327may remove effectively the noise components450and460.

FIG. 14is a schematic block diagram of an NFC device according to an example embodiment.

Referring toFIG. 14, an NFC device700according to an example embodiment may include a clock generating unit701, a coil unit702, a transmitting module710, a receiving module720, and a gain control unit730. The transmitting module710may include a divider711, a DC-DC control unit712, a DC-DC converter713, and a power amplifier714. The receiving module720may include a matching network721, an attenuator722, a mixer723, a first filter724, a variable-gain amplifier725, an analog-to-digital converter726, and a second filter727. Operations of the transmitting module710and the receiving module720may be similar to those of the transmitting module310and the receiving module320according to the example embodiment illustrated inFIG. 4.

The gain control unit730may detect magnitudes of at least some signals from the receiving module720by first to third power detectors (PD1to PD3)703to705. The gain control unit730may control the attenuator722and the variable-gain amplifier725, based on the magnitudes of the at least some signals detected by the first to third power detectors703to705.

The first power detector703may detect a magnitude of a signal at an input, terminal of the mixer723. The gain control unit730may adjust an attenuation amount of the attenuator722with reference to the detection result of the first power detector703. In an example embodiment, the gain control unit730may adjust the attenuation amount of the attenuator722, such that a signal input to the mixer723may have sufficient linearity.

The second power detector704may detect the magnitude of the signal at an output terminal of the ADC726, and the third power detector705may detect the magnitude of the signal at an output terminal of the second filter727. The second power detector704and the third power detector705may be provided to obtain a maximum value of the signal-to-noise ratio, while preventing an analog signal, input to the analog-to-digital converter726, from being saturated. For example, when the gain control unit730changes a gain of the variable-gain amplifier725, the gain control unit730may consider the detection result of each of the second power detector704and the third power detector705.

In an example embodiment, when it is difficult to obtain a sufficient signal-to-noise ratio, due to a small magnitude of signal detected at the output terminal of the second filter727by the third power detector705, the gain control unit730may refer to the magnitude of the signal detected at the output terminal of the analog-to-digital converter726. When the magnitude of the signal detected at the output terminal of the analog-to-digital converter726is at saturation point, it may be assumed that an analog signal having a magnitude outside a dynamic range of the analog-to-digital converter726is input to the analog-to-digital converter726.

Thus, when the magnitude of the signal detected by the second power detector704is at saturation point, the gain control unit730may lower the gain of the variable gain amplifier725. In contrast, when the magnitude of the signal detected by the second power detector704is not at saturation point, the gain control unit730may raise the gain of the variable-gain amplifier725to improve the signal-to-noise ratio.

When adjusting the gain of the variable-gain amplifier725with reference to only the signal detected at the output terminal of the second filter727, the gain control unit730may increase the gain of the variable-gain amplifier725if the signal detected at the output terminal of the second filter727is weak, so that the analog signal having the magnitude outside the dynamic range may be input to the variable-gain amplifier726. In an example embodiment, when the magnitude of the signal detected by the third power detector705is small, the gain control unit.730may determine whether the output of the analog-to-digital converter726is saturated, based on the magnitude of the signal detected by the second power detector704, and increase or decrease the gain of the variable-gain amplifier725. Thus, setting an optimal gain value may allow an excellent signal-to-noise ratio, while preventing the output of the analog-to-digital converter726from being saturated.

FIG. 15is a block diagram of an electronic device including an NFC device according to an example embodiment.

Referring toFIG. 15, an electronic device1000according to an example embodiment may include a display1010, a memory1020, a communications module1030, a sensor module1040, and a processor1050. The electronic device1000may include a television and a desktop personal computer (PC), in addition to a mobile device, such as a smartphone, a tablet PC, or a laptop PC. The components, such as the display1010, the memory1020, the communications module1030, the sensor module1040, and the processor1050, may communicate with each other through a bus1060.

The communications module1030may include the NFC device according to various example embodiments. To improve performance, the transmitting module of the NFC device may include the power amplifier and the DC-DC converter, supplying a power supply voltage to the power amplifier. The power amplifier may amplify the magnitude of the carrier signal required for NFC communications. The electronic device1000may include various communications modules and, in recent years, the electronic device1000including a wireless charging module has been increasing. Thus, when the magnitude of the carrier signal required for NFC communications is small, performance may be reduced and, in an embodiment, the power amplifier may be employed in the transmitting module of the NFC device, solving the above-mentioned issue.

The receiving module of the NFC device may include the notch filter in order to improve the SNR by effectively removing the noise component included in the reception signal. The switching frequency of the DC-DC converter may correspond to the notch frequency of the notch filter or the harmonic components thereof. Thus, the notch filter may remove the noise component included in the output of the power amplifier receiving the power supply voltage from the DC-DC converter, resulting in an improvement in the SNR.

As set forth above, according to example embodiments of the present inventive concept, an NFC device may increase an NFC distance, using a transmitter that receives power from a direct current-direct current (DC-DC) converter to generate a carrier signal, while effectively removing noise components included in the carrier signal by the DC-DC converter by providing a filter in a signal receiving unit. Further, power consumption of the NFC device may be efficiently managed by determining an operating mode of the DC-DC converter according to an operating state of the NFC device.