JP2011124672A - Communication device, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication device for performing excellent communication even in high-speed communication by modulation degree control. <P>SOLUTION: In the communication device including a transmission signal generation section for generating transmission signals by executing modulation processing of superimposing transmission information to carrier signals by amplitude modulation and a control section for executing the control of the transmission signal generation section, the control section executes the control of making the transmission signal generation section execute the modulation processing of a different modulation degree corresponding to a communication rate. The transmission signal generation section generates the transmission signals by executing the modulation processing of the different modulation degree corresponding to the communication rate according to the control by the control section. To put it concretely, the transmission signals are generated by executing the modulation processing in which the modulation degree is increased as the communication rate becomes high. By this configuration, in particular, a magnetic field strength level near a sideband during the high-speed communication can be improved, and the excellent communication is achieved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication device and a communication control method. For example, the present invention relates to a communication device that can be used for proximity communication executed in an IC card or the like, and a communication control method.

  In recent years, mobile terminals such as an IC card and a mobile phone having a proximity communication function are widely used. For example, FeliCa (registered trademark) which is an IC card developed by Sony Corporation is known. As a communication standard for near field communication, for example, there is NFC (Near Field Communication) standard which is a short-range wireless communication standard developed by Sony and Philips.

  In proximity communication, for example, a carrier frequency of 13.56 MHz is used, and communication is performed with a distance between transmission and reception ranging from close contact (0 mm) to about 100 mm. The outline of this communication will be described with reference to FIG. At this distance, it can be thought of as magnetic coupling using a transmitting / receiving antenna as a coil. A pair of transformers.

A data transmission process from the reader / writer 10 to a transponder 20 such as an IC card will be described with reference to FIG.
As shown in FIG. 1A, the reader / writer 10 inputs the transmission information (signal S1a) of 212 kbps to the gain switching amplifier 11 to generate a modulation signal (signal S1b), and generates the generated modulation signal (signal S1b). Modulation processing that superimposes the modulation signal on the 13.56 MHz carrier signal (signal S1c) is input to the modulator (multiplier) 12 to generate a transmission signal (signal S1d).

Further, the transmission signal (signal S1d) is input to the antenna circuit 14 including a coil or the like via the transmission amplifier 13, and an antenna transmission signal (signal S1e) is generated and transmitted to the transponder 20.
The transponder 20 receives the received signal via the coil, and the detection circuit 21 analyzes the received signal.

In FIG.
Transmission information waveform (signal S1a)
Modulation signal waveform (signal S1b)
Carrier signal waveform (signal S1c)
Transmission signal waveform (signal S1d)
Antenna signal waveform (signal S1e)
The signal waveforms of these signals S1a to S1e are shown.
For example, an ASK modulation (Amplitude Shift Keying) method is employed as a modulation method of the carrier signal (signal S1c) using the modulation signal (signal S1b).

  Communication between the reader / writer 10 and the transponder 20 shown in FIG. 1 with the distance between transmission and reception in the range of close contact (0) to several tens of centimeters is performed. At this distance, it may be considered that magnetic coupling is performed using the transmitting / receiving antenna as a coil.

  As described above, for example, NFC standard non-contact communication such as FeliCa (registered trademark) which is an IC card developed by Sony uses a 13.56 MHz carrier, and the distance between transmission and reception is about 100 mm from close contact (0 mm). Communication is performed.

  As described with reference to FIG. 1, one side of this transmission / reception system is called a reader / writer, and the other side is called a transponder. Only the reader / writer generates a carrier signal. At the time of data transmission from the reader / writer to the transponder, as described above, the carrier is ASK (Amplitude Shift Keying) modulated and transmitted by the modulation signal (S1b) that is a signal generated based on the transmission data. This modulation is performed by multiplying a carrier signal and a modulation signal (S1b) that is a signal generated based on transmission data.

  On the other hand, when data is transmitted from a transponder such as an IC card to the reader / writer, data transmission by load modulation is executed. In this method, a carrier signal generated and transmitted by a reader / writer is received, and the received carrier signal is subjected to modulation processing by transmission information generated on the transponder side such as an IC card, that is, load modulation is performed. On the reader / writer side, the transponder (IC card) receives the modulation result data modulated by the transmission information (modulated signal) with respect to the carrier signal transmitted by the reader / writer side, analyzes it, and transmits the transmission information from the transponder (IC card). To get.

The signal waveform shown in FIG. 1B will be further described in detail with reference to FIG. In FIG.
(1) Transmission information waveform (signal S1a)
(2) Modulation signal waveform (signal S1b)
(3) Carrier signal waveform (signal S1c)
(4) Transmission signal waveform (signal S1d)
The signal waveforms of these four signals S1a to S1d are shown.

  (1) The transmission information waveform (signal S1a) is a signal string composed of data 1/0 to be transmitted. (2) A modulated signal waveform (signal S1b) is generated by signal processing by the gain switching amplifier 11 shown in FIG. The gain switching amplifier 11 generates a signal level of, for example, 1 and 0.9 for each of the transmission data 1 and 0, and generates a modulation signal waveform (signal S1b) shown in FIG. To do.

  When the modulation signal waveform (signal S1b) shown in FIG. 2 (2) is multiplied by (3) the carrier signal (signal S1c), when the data is 1, the multiplication result remains at the carrier signal level. On the other hand, when the data is 0, since the value applied to the carrier is 0.9, the amplitude of the carrier signal is reduced by 10%, and (4) a transmission signal waveform as a modulated signal in which a change in amplitude according to transmission data 1/0 appears. (Signal S1d) is generated. That is, the carrier signal is amplitude-modulated with the transmission data.

As shown in FIG. 2 (4), in the transmission signal waveform (signal S1d), a large amplitude value is a, and a small amplitude value is b. A value represented by the following expression by a and b is called a modulation degree.
(A−b) / (a + b) × 100 (%)

  The larger the degree of modulation, the greater the carrier amplitude change, so the amplitude of the detected signal at the receiver increases, communication with a larger SNR (Signal to Nose Ratio) and fewer errors, and communication over a longer distance. There are advantages. However, on the other hand, it also has a disadvantage that an extra sideband level appearing in frequency bands before and after the communication frequency band becomes large.

  The sideband is a signal spectrum generated in the vicinity of the carrier frequency by modulating the carrier. Since it is natural that a strong electric field or magnetic field is generated at the carrier frequency, the carrier frequency level is regulated and regulated. In addition, the sidebands near the carrier frequency also have spectrum limitations. If this is too strong, it can be a disturbing radio wave for other electronic devices.

The Japanese sideband standard in communications with a 13.56 MHz carrier will be described with reference to FIG. In the graph of FIG.
The horizontal axis is a frequency of 8.56 to 18.56 MHz,
The vertical axis represents the magnetic field strength (dBμA / m).
It is.
The center of the horizontal axis corresponds to a carrier frequency of 13.56 MHz.
The thick line on the stairs shown in FIG. 3 is a Japanese sideband standard line.

  Even when communication is performed at a carrier frequency of 13.56 MHz, a magnetic field in a frequency band in the vicinity thereof is generated. The thick line on the staircase shown in FIG. 3 is a Japanese sideband standard line, which corresponds to the maximum allowable standard for the magnetic field strength measured by the 10 m method. Communication below the sideband standard line is an area allowed by the standard. That is, the standard requires that the magnetic field intensity does not exceed the sideband standard line indicated by the thick line on the staircase shown in FIG.

If the degree of modulation is increased in order to improve the communication quality, the level of the sideband may exceed the standard even if the level of the carrier itself falls within the standard, so it cannot be increased unnecessarily. Incidentally, when the modulation degree is doubled, the sideband amplitude is doubled.
FIG. 3 shows sideband levels at the time of communication execution at six communication rates with a communication rate of 3.4 Mbps to 106 Mbps.

  A communication rate used for proximity communication using a conventional IC card or the like, for example, a standard communication rate of FeliCa (registered trademark) is 212 kbps. Doubled 424 kbps is also standardized and used. The magnetic field strength levels of 212 kbps and 424 kbps used in a communication device such as a commercially available IC card are designed so as to be within the sideband standard shown in FIG.

  That is, the configuration of the antenna circuit or the modulation degree of the modulation signal applied to the modulation processing executed when generating the modulation signal is fixed and used so that the setting is within the sideband standard shown in FIG.

  In the future, it is predicted that a proximity communication configuration at a communication rate higher than the conventional 212 kbps and 424 kbps, such as a high communication rate, for example, a communication rate of 3.4 Mbps, will be used. However, in such high-speed communication, a communication processing configuration for setting to fit within the standard shown in FIG. 3 has not been sufficiently studied. Specifically, no clear proposal has been made regarding the optimal transceiver and communication processing configuration for ensuring a sufficient communicable distance without departing from the sideband standard shown in FIG. Currently.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a communication device and a communication control method that enable optimal communication according to a communication rate.

The first aspect of the present invention is:
A transmission signal generation unit that generates a transmission signal by performing modulation processing for superimposing transmission information on the carrier signal by amplitude modulation;
A control unit that executes control of the transmission signal generation unit;
The controller is
Performing control to cause the transmission signal generation unit to perform modulation processing of different modulation degrees according to the communication rate,
The transmission signal generator is
According to the control of the control unit, the communication apparatus generates a transmission signal by executing modulation processing with different modulation degrees according to a communication rate.

  Furthermore, in one embodiment of the communication apparatus of the present invention, the control unit performs control to cause the transmission signal generation unit to perform modulation processing with a modulation degree increased as the communication rate increases, and the transmission signal generation unit In accordance with the control of the control unit, the transmission signal is generated by executing a modulation process in which the modulation degree is increased as the communication rate is increased.

  Furthermore, in one embodiment of the communication apparatus of the present invention, the control unit provides the transmission signal generation unit with amplitude setting information of a transmission signal corresponding to 0 and 1 of the transmission information.

  Furthermore, in an embodiment of the communication apparatus of the present invention, the control unit further provides the transmission signal generation unit with amplitude setting information of a transmission signal at the time of no modulation.

  Furthermore, in an embodiment of the communication apparatus of the present invention, the control unit sets an amplitude of a transmission signal at the time of non-modulation between amplitudes of transmission signals corresponding to 0 and 1 of the transmission information. Information is provided to the transmission signal generator.

  Furthermore, in an embodiment of the communication apparatus of the present invention, the transmission signal generation unit includes a register that stores amplitude setting information provided by the control unit, and a current source that generates a current corresponding to the stored value of the register. And generating a transmission signal in which different amplitudes are set according to the value of the transmission information by executing current control of the current source according to the value of the transmission information.

  Furthermore, in an embodiment of the communication apparatus of the present invention, the transmission signal generation unit executes a transmission signal generation process using a differential amplifier circuit.

  Furthermore, in an embodiment of the communication apparatus according to the present invention, the transmission signal generation unit executes a transmission signal generation process using an H bridge circuit.

Furthermore, the second aspect of the present invention provides
A control unit that executes control of load modulation for superimposing transmission information by amplitude modulation on a reception carrier signal;
The controller is
The communication apparatus executes a modulation process set to a different modulation degree according to a communication rate.

  Furthermore, in one embodiment of the communication apparatus of the present invention, the control unit executes a modulation process in which the modulation degree is increased as the communication rate is increased.

  Furthermore, in an embodiment of the communication apparatus of the present invention, the control unit performs a process of adjusting a Q value (quality factor) of an antenna circuit that outputs the transmission information according to a communication rate.

  Furthermore, in an embodiment of the communication apparatus of the present invention, the control unit performs a process of adjusting a resistance value of an antenna circuit that outputs the transmission information according to a communication rate.

  Furthermore, in one embodiment of the communication apparatus of the present invention, the controller performs a process of controlling a current value flowing in the antenna circuit that outputs the transmission information according to a communication rate.

  Furthermore, in an embodiment of the communication apparatus according to the present invention, the control unit performs a process of controlling a current value flowing in an antenna circuit that outputs the transmission information according to a value of the transmission information.

Furthermore, the third aspect of the present invention provides
A communication control method executed in a communication device,
A step of executing control for causing the transmission signal generation unit to perform modulation processing of different modulation degrees according to a communication rate;
When the transmission signal generation unit performs a modulation process for superimposing transmission information on the carrier signal by amplitude modulation, the transmission signal is generated by performing a modulation process with a different modulation degree according to the communication rate according to the control of the control unit. A step of generating
There is a communication control method.

  Other objects, features, and advantages of the present invention will become apparent from a more detailed description based on embodiments of the present invention described later and the accompanying drawings.

  According to the configuration of one embodiment of the present invention, a transmission signal generation unit that generates a transmission signal by performing modulation processing for superimposing transmission information on a carrier signal by amplitude modulation, and performs control of the transmission signal generation unit In the communication apparatus having the control unit, the control unit performs control to cause the transmission signal generation unit to perform modulation processing with different modulation degrees according to the communication rate, and the transmission signal generation unit responds to the communication rate according to the control of the control unit. A transmission signal is generated by executing modulation processing with different modulation degrees. Specifically, a transmission signal is generated by executing a modulation process in which the modulation degree is increased as the communication rate is increased. With this configuration, it is possible to improve the magnetic field strength level in the vicinity of the sideband particularly during high-speed communication, and good communication is realized.

It is a figure explaining the general structure of the communication apparatus which performs near field communication, and the example of a process of the transmitted / received signal in a communication process. It is a figure explaining each signal waveform in near field communication. It is a figure explaining the magnetic field strength standard in near field communication. It is a figure explaining the conversion process to Manchester code. It is a figure explaining a resonance gain characteristic. It is a figure explaining the magnetic field strength distribution of the sideband after Manchester code conversion. It is a figure explaining the modulation control which the communication apparatus which concerns on one Example of this invention performs. It is a figure explaining the structural example of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the signal waveform explaining the process of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the signal waveform explaining the process of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the current source in the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the signal waveform explaining the process of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the signal waveform explaining the process of the transmission signal generation part of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the process example of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the communication apparatus which concerns on one Example of this invention. It is a figure explaining the structural example of the communication apparatus which concerns on one Example of this invention.

Hereinafter, the communication apparatus and the communication control method of the present invention will be described in detail with reference to the drawings.
Hereinafter, the present invention will be sequentially described according to the following items.
1. 1. Outline of processing executed by communication apparatus of present invention 2. Configuration example of communication device of the present invention 3. Specific Example of Transmission Signal Generation Unit of Communication Device of the Present Invention 3-1. Example 1 of transmission signal generator
3-2. Embodiment 2 of transmission signal generator
3-3. Embodiment 3 of transmission signal generator
4). Communication device that executes data transmission by load modulation 4-1. Example of modulation degree control in load modulation (Example 4)
4-2. Example of modulation degree control in load modulation (Example 5)
4-3. Example of modulation degree control in load modulation (Example 6)

[1. Outline of processing executed by communication device of present invention]
First, an outline of processing executed by the communication apparatus of the present invention will be described. The aforementioned FeliCa (registered trademark) standard packet information, which is an IC card developed by Sony, is converted into a Manchester code and transmitted / received.
In particular,
[0] of the transmission information is converted to [01] of Manchester code,
[1] of the transmission information is converted to [10] of Manchester code.
That is, each 1 bit included in the transmission information is converted into 2 bits, that is, a double rate.

This data conversion will be described with reference to FIG.
In FIG.
(A) Original data (transmission information)
(B) Manchester code (c) Manchester code carrier modulation waveform These data examples are shown.

  The process of converting (coding, encoding) original data (transmission information) into Manchester code is to convert 1-bit transmission data into 2-bit transmission code. Transmission data [0] is converted to code [01 (low, high)], and transmission data [1] is converted to code [10 (high, low)].

  This Manchester code conversion process is coding for converting 1 bit into 2 bits. That is, the minimum inversion interval of the code string is ½ of the inversion interval of the transmission data. Therefore, for example, if the information rate is 212 kbps, the Manchester code is 424 kbps. In general, the communication rate is often expressed not by the code rate but by the information rate, and is defined here as well.

  The standard rate for FeliCa® is 212 kbps. Doubled 424 kbps is also used in the standard. Naturally, the commercially available magnetic field strength levels of 212 kbps and 424 kbps are within the standards. FIG. 3 shows sideband spectra of six Manchester codes from 106 kbps to 3.4 Mbps in addition to the regulation level. The degree of modulation is the same at any communication rate. However, the absolute value of the level was drawn so that the sideband levels of 212 kbps and 424 kbps would be the maximum not exceeding the standard value.

  Since the Manchester code having a communication rate of 212 kbps is 424 kbps, 1 or 0 is switched at a cycle of 424 kHz. The reason why 1/0 is inverted in the shortest cycle is 1/0 changes every cycle of 424 kHz, and therefore the frequency of the repeated waveform is 212 kHz. This shortest cycle is represented as 1T. 1T is 1/212 kHz time. In order to transmit a 1T continuous waveform with carrier modulation, it is necessary to transmit from 13.348 MHz which is −212 kHz to 13.56 MHz to 13.772 MHz which is +212 kHz to 13.56 MHz to the receiving unit. Table 1 below shows data in which bandwidths necessary for communication are summarized for each communication rate.

Table 1 shows
Communication data rate (nominal),
Communication data rate (exact value),
Bandwidth required for communication,
The correspondence of these data is shown.

The required bandwidth is displayed by rounding down the second decimal place in MHz at the lower limit frequency and rounding up at the upper limit frequency.
When the communication rate is increased, the sideband as a necessary band is increased in proportion thereto. Naturally, since a band that increases in proportion to the communication rate is used at the time of reception, the band of noise to be picked up also increases in proportion. Assuming that the noise is constant white noise regardless of frequency, if the band is doubled, the noise amplitude becomes √2 times, so if the communication rate is doubled, the SNR deteriorates by 3 dB.

  The spectrum of the modulation signal shown in FIG. 3 described above corresponds to the output of the modulator (multiplier) 12 in FIG. When this signal enters the parallel resonant circuit of the LCR that constitutes the antenna circuit 14 via the current output transmission amplifier 13 in FIG. 1, the resonance frequency is determined by the characteristics of the parallel resonant circuit of the LCR that constitutes the antenna circuit 14. Is converted into a signal having a large gain and transmitted.

  FIG. 5 shows the resonance characteristics when the quality factor (Q) representing the sharpness of resonance is 20. FIG. When the quality factor (Q) is increased, the resonance frequency characteristic becomes steep near the carrier frequency (13.56 MHz), and when the quality factor (Q) is decreased, the frequency characteristic becomes gentle. The quality factor (Q) is determined by the characteristics of the antenna circuit (LCR circuit). FIG. 5 shows resonance characteristics when the quality factor (Q) is 20. FIG. Due to this resonance characteristic, the spectrum decreases as the distance from the carrier frequency (13.56 MHz) increases.

FIG. 6 shows a sideband spectrum modulated by a Manchester code in consideration of the resonance characteristic of Q = 20. As understood from FIG. 6, the spectrum of 3.4 Mbps is 19 dB lower than the regulation level.
Thus, it is understood that when transmission is performed at a high transmission rate (3.4 Mbps), the magnetic field strength is extremely reduced more than necessary at the carrier frequency and the sideband. Such a decrease in magnetic field strength means that the communication limit distance is shortened. That is, there is an adverse effect that accurate communication cannot be performed unless the distance between the transmitting and receiving apparatuses is shortened.

For example, in the case of 3.4 Mbps, which reaches only a level that is 19 dB lower than the regulation line shown in FIG. 6, the modulation degree is controlled to increase the carrier amplitude difference by 19 dB, that is, about 9 times, so that the level just reaches the regulation line. Become.
For example, when communication is performed at a higher communication rate, the spectrum level increases as the modulation degree increases, and a larger SNR is obtained accordingly. In the case of the setting of FIG. 6, there is no concern over exceeding the regulations of the Radio Law even if the carrier amplitude difference due to modulation is doubled when the communication rate is doubled.

  The communication device of the present invention pays attention to such a change in the magnetic field strength of the sideband region according to the communication rate, and performs control to change the magnetic field strength of the sideband region according to the communication rate. That is, a transmission signal whose modulation degree is changed according to the communication rate is generated and output. Specifically, for example, with respect to the unmodulated carrier level, when the transmission information (modulation data) = 1, a higher level is set, and when the transmission information (modulation data) = 0, a lower carrier level is set. Execute.

A specific modulation degree changing process example will be described with reference to FIG. In FIG.
(1) Transmission information waveform (signal S1a)
(2) Modulation signal waveform (signal S1b)
(3) Carrier signal waveform (signal S1c)
(4) Transmission signal waveform (signal S1d)
The signal waveforms of these four signals S1a to S1d are shown. These signals correspond to the signals (1) S1a to (4) S1d described above with reference to FIG.

As described above, (4) in the transmission signal waveform (signal S1d), the amplitude value of a large amplitude is a and the amplitude value of a small amplitude is b. Degree.
(A−b) / (a + b) × 100 (%)
The larger the degree of modulation, the greater the carrier amplitude change, so the amplitude of the detected signal at the receiver increases, communication with a larger SNR (Signal to Nose Ratio) and fewer errors, and communication over a longer distance. There are advantages.

FIG. 7 is a diagram illustrating the concept of transmission signal generation processing in which different modulation degrees A, B, and C are set according to the communication rate. In FIG.
(1) Transmission information signal (2) Modulation signal with different modulation degree corresponding to transmission information (3) Carrier signal (4) Transmission signal waveform with different modulation degree These signals are shown.

The communication apparatus of the present invention performs, for example, the following modulation degree control.
Communication rate = low-> modulation factor = small (modulation factor A)
Communication rate = medium → modulation factor = medium (modulation factor B)
Communication rate = high-> modulation factor = large (modulation factor C)

As a result, a transmission signal having a different modulation degree is generated and output according to the transmission rate shown in FIG. When the modulation degree calculation formulas described above using the parameters (amplitude value a of large amplitude and amplitude values b1 to b3 of small amplitude) shown in FIG. , C is expressed by the following equation.
Modulation degree A = (a−b1) / (a + b1) × 100 (%)
Modulation degree B = (a−b2) / (a + b2) × 100 (%)
Modulation degree C = (a−b3) / (a + b3) × 100 (%)

  For example, a signal having a large modulation degree, such as a modulation degree C, has a larger carrier amplitude change, and communication with fewer errors can be performed. However, if the degree of modulation is increased as described above, the sideband level may exceed the standards shown in FIG. 3 and FIG. 6, so it cannot be increased unnecessarily. When the degree of modulation is doubled, the sideband amplitude is about doubled.

  However, as understood from FIG. 6, the spectrum of 3.4 Mbps is as low as 19 dB from the regulation level, and even if the sideband amplitude increases, the possibility of exceeding the regulation level is low. Therefore, the theory holds that the higher the communication rate, the more room exists to increase the modulation factor.

  The communication apparatus of the present invention executes control to increase the modulation degree according to the communication rate according to this theory. Increasing the degree of modulation corresponds to increasing the difference between the amplitude value a having a large amplitude and the amplitude value b having a small amplitude in the transmission signal waveform (the signal shown in FIG. 7 (4)). Increasing the modulation degree increases the magnetic field strength of the transmission signal, and moves the sideband spectrum shown in FIG. 6 in the upward direction, that is, in the direction of arrow [A]. As a result, communication with a large SNR (Signal to Nose Ratio) and fewer errors can be performed, and communication can be performed over a longer distance.

  The communication apparatus according to the present invention has a configuration in which the modulation level is changed according to the communication rate to increase the magnetic field strength and the transmission signal is generated within a range in which the magnetic field strength level does not deviate from the sideband standard shown in FIGS. Have. The detailed configuration of the communication apparatus of the present invention will be described below.

[2. Configuration example of communication apparatus of the present invention]
FIG. 8 is a diagram showing the configuration of an embodiment of the communication apparatus of the present invention. This communication apparatus corresponds to the reader / writer 10 shown in FIG. 1, and generates a modulation signal in which transmission information is superimposed on a carrier signal of 13.56 MHz, for example, by amplitude modulation, and executes data transmission. The transmission information is received at the receiving side corresponding to the transponder 20 shown in FIG. 1, and the received information is analyzed.

A configuration of the communication apparatus 100 of FIG. 8 will be described. The communication apparatus 100 includes a transmission signal generation unit 101, an antenna circuit 102, a control unit 1103, and a reception signal detection unit 104.
The transmission signal generation unit 101 generates, for example, a transmission signal superimposed on a 13.56 MHz carrier signal 122 and transmission information 121. The transmission signal is transmitted via the antenna circuit 102.

The transmission signal generation unit 101 generates a transmission signal by executing modulation processing with different modulation degrees according to the transmission rate described above with reference to FIG.
The control unit 103 performs a process of determining the modulation degree set in the transmission signal generation unit 101, and executes control of the transmission signal generation unit 101 according to the determination information.
The reception signal detection unit 104 detects reception information from a communication partner apparatus that performs communication with the communication apparatus 100, for example, a transponder such as an IC card.

  For example, the communication device 100 performs trial communication (polling) at a plurality of different communication rates. Specifically, test transmission is executed by gradually increasing the communication rate in the range of, for example, 212 Kbps to 3.4 Mbps. The reception signal detection unit 104 checks whether or not normal reception confirmation for each test communication data of each communication rate has been obtained from the communication partner apparatus (transponder).

  For example, normal reception confirmation is obtained from the communication partner device (transponder) for the test transmission data of 212 Kbps to 424 Kbps, and normal reception confirmation is received from the communication partner device (transponder) for the test transmission data of 848 Kbps to 3.4 Mbps. When the confirmation is not obtained, the control unit 103 determines that the communication partner device (transponder) is a device having a maximum allowable communication rate of 424 Kbps, and sets the communication rate of 424 Kbps to the transmission signal generation unit 101. Settings and control are performed to generate transmission data in which a corresponding modulation degree is set.

  For example, when the normal reception confirmation is obtained from the communication partner device (transponder) for all the test transmission data of 212 Kbps to 3.4 Mbps, the control unit 103 determines that the communication partner device (transponder) is 3.4 Mbps. Is determined to be a device having the maximum allowable communication rate, and the transmission signal generation unit 101 is set and controlled to generate transmission data in which the modulation degree corresponding to the communication rate of 3.4 Mbps is set. .

A configuration example of the transmission signal generation unit 101 will be described with reference to FIG. The transmission signal generation unit 101 performs processing having the configuration of the gain switching amplifier 11, the modulator 12, and the transmission amplifier 13 of the reader / writer 10 shown in FIG.
As illustrated in FIG. 9, the transmission signal generation unit 101 includes a modulation unit 201, a transmission amplifier 202, and a modulation degree setting information input unit 203.

As described above, the control unit 103 determines the maximum communication rate information allowed by the communication partner apparatus (transponder), determines the modulation degree to be set in the transmission signal according to the determination information, and sets the modulation degree to the determined modulation degree. The corresponding setting information is input to the modulation degree setting information input unit 203. Specifically, the amplitude setting information of the transmission signal is input to the modulation degree setting information input unit 203.
The control unit 103 holds correspondence data between the communication rate to be set and the setting information to be set in the modulation degree setting information input unit 203, for example, table data, and sets the setting information in the modulation degree setting information input unit 203 according to this data. Set.

  The modulation unit 201 generates a modulation signal in which a modulation degree corresponding to the information input to the modulation degree setting information input unit 203 is set as a transmission signal. Specifically, as described with reference to FIG. 7, when the transmission rate is low, the modulation degree is reduced, and when the transmission rate is high, a transmission signal with a large modulation degree is generated. Note that the generated signal of the modulation unit 201 is amplified through the transmission amplifier 202 and then output through the antenna circuit 1102 as a transmission signal.

[3. Specific Example of Transmission Signal Generation Unit of Communication Device of the Present Invention]
Hereinafter, a plurality of embodiments of specific circuit examples of the transmission signal generation unit will be described.

[3-1. First Embodiment of Transmission Signal Generation Unit]
FIG. 10 is a diagram illustrating a specific circuit configuration example of the transmission signal generation unit 101. In the transmission signal generation unit 101 illustrated in FIG. 10, the i2 setting register 225 and the i1 setting register 226 illustrated in the lower stage correspond to the modulation degree setting information input unit 203 illustrated in FIG. 9. The upper circuit corresponds to a circuit in which the modulation unit 201 and the transmission amplifier 202 shown in FIG.

  The control unit 103 determines the maximum allowable communication rate of the communication partner acquired by the above-described test transmission processing such as polling, and sets the i2 setting register 225 corresponding to the modulation degree setting information input unit 203 illustrated in FIG. Modulation degree setting information for setting a modulation degree corresponding to the determined transmission data communication rate is set in the register 226. Specifically, transmission signal amplitude setting information is input.

In the case of the circuit configuration shown in FIG. 10, the setting information [i2] of the output current value of the current source a223 is set in the i2 setting register 225. In the i1 setting register 226, the setting information [i1] of the output current value of the current source b224 is set.
The degree of modulation is changed according to the set current values i1 and i2.

  The control unit 103 holds data corresponding to the determined communication rate and the setting information to be set in the i2 setting register 225 and the i1 setting register 226 shown in FIG. 10, for example, table data, and the i2 setting register 225 and the data corresponding to this data are stored. Setting information [i2] and [i1] are set in the i1 setting register 226.

The current source a223 shown in FIG. 10 inputs a 1/0 signal that is a transmission information signal (modulation signal) from a transmission information signal (modulation signal) input unit 231;
When the transmission information signal (modulation signal) = 1, the signal is turned on and the current value i2 is output.
When the transmission information signal (modulation signal) = 0, the signal is turned OFF and the output of the current value i2 is stopped.
The current source b224 is always ON and outputs a current value i1.
FIG. 11 shows a signal waveform example of each circuit unit shown in FIG.

FIG. 11 shows the following signal waveforms.
(1) Carrier signal (2) Transmission information signal (modulated signal)
(3) Input signal (i5) of transistor (Q1) 221
(4) Input signal (i6) of transistor (Q2) 222
(5) Transmission signal (i3)

The transistor (Q1) 221 and the transistor (Q2) 222 shown in FIG. 10 constitute a differential amplifier circuit.
The carrier signal is input to the transistor (Q1) 221 from the carrier signal input unit 232, and the transistor (Q1) 221 is controlled to be turned on / off according to the 1/0 pattern of the carrier signal.
On the other hand, the carrier signal inversion signal is input to the transistor (Q2) 222 from the carrier signal inversion signal input unit 233, and the transistor (Q2) 222 is subjected to ON / OFF control according to the 1/0 pattern of the carrier signal inversion signal. Do.

As a result, the input signal waveform of the transistor (Q1) 221 is the signal waveform shown in FIG.
Further, the input signal waveform of the transistor (Q2) 222 is the signal waveform shown in FIG.
The input signal waveform of the transistor (Q1) 221 and the input signal waveform of the transistor (Q2) 222 have opposite patterns.

Note that when the transmission information signal (modulation signal) = 1, the current sources a and 223 are turned on, so the input current of each transistor is
i1 + i2.
In addition, when the transmission information signal (modulation signal) = 0, the current sources a and 223 are turned off, so that the input current of each transistor is
Set to i1.

A signal pattern corresponding to the fluctuation of the transistor input current is a transmission signal (i3) as an output to the antenna circuit 102 shown in FIG. The signal waveform of the transmission signal is the waveform shown in FIG. 11 (5) transmission signal (i3).
The amplitudes of the transmission information signal (modulated signal) = 1 and 0 are set as follows.
When transmission information signal (modulated signal) = 1,
Amplitude i3 _max = ((2Z1) / (2Z1 + Z2)) (i1 + i2)
When transmission information signal (modulated signal) = 0,
Amplitude i3 _min = ((2Z1) / (2Z1 + Z2)) (i1)

In the above formula, i1, i2, Z1, and Z2 are the following values.
i1: A value set in the i1 setting register 226 by the control unit 103, and a current value flowing through the current sources b and 224,
i2: a value set in the i2 setting register 225 by the control unit 103, the current flowing through the current sources a and 223,
Z1: a load resistor Z1 connected to the supply voltage Vcc shown in FIG.
Z2: load resistance Z2 of the antenna circuit 102,
These values.

As described above, the degree of modulation is represented by the following equation, where a is a large amplitude value and b is a small amplitude value.
Modulation factor = (a−b) / (a + b) × 100 (%)
Therefore, the modulation degree of the transmission signal (i3) shown in FIG. 11 (5) is calculated by the following equation.
Modulation _{= (i3 max -i3 min) /} (i3 max + i3 min) × 100 (%)
= [((2Z1) / (2Z1 + Z2)). (I1 + i2-i1)] / [((2Z1) / (2Z1 + Z2)). (I1 + i2 + i1)]
= (I2) / (2i1 + i2)

Thus, the modulation degree is the setting information set according to the communication rate determined by the control unit 103, that is,
The set value [i1] of the i1 setting register 226 shown in FIG.
The set value [i2] of the i2 setting register 225 shown in FIG.
The degree of modulation is determined by these values.
When the transmission rate is set high, the control unit 103 determines i1 and i2 that increase the degree of modulation and sets them in each register.
In addition, when setting the transmission rate to be low, the control unit 103 determines i1 and i2 so that the degree of modulation becomes small and sets it in each register.

As described above, the control unit 103 should determine the maximum communication rate allowed by the communication partner apparatus (transponder) according to the result of, for example, test transmission, and set the transmission signal according to the determination information. The modulation degree is determined, and setting information [i1] and [i2] corresponding to the determined modulation degree are set. The control unit 103 holds correspondence data between the communication rate to be set and the setting information, for example, table data, and inputs the setting information to the i1 setting register 226 and the i2 setting register 225 according to this data.
With such a configuration, it is possible to generate and output a transmission signal in which different modulation degrees are set according to the communication rate.

[3-2. Second Embodiment of Transmission Signal Generation Unit]
Next, a second embodiment of the transmission signal generation unit will be described with reference to FIGS.
FIG. 12 is a diagram illustrating a specific circuit configuration example of the transmission signal generation unit 101 according to the second embodiment.
FIG. 13 is a diagram showing signal waveforms at various parts of the circuit of FIG.

  In the transmission signal generation unit 101 shown in FIG. 12, an i4 setting register 246, an i2 setting register 247, and an i1 setting register 248 shown in the lower part correspond to the modulation degree setting information input unit 203 shown in FIG. The upper circuit corresponds to a circuit in which the modulation unit 201 and the transmission amplifier 202 shown in FIG.

  The control unit 103 determines the maximum allowable communication rate of the communication partner acquired by the above-described test transmission process such as polling, and the i4 setting register 246 and i2 setting register corresponding to the modulation degree setting information input unit 203 illustrated in FIG. In 247 and i1 setting register 248, modulation degree setting information for setting a modulation degree corresponding to the determined transmission data communication rate is set. Specifically, transmission signal amplitude setting information is input.

In the case of the circuit configuration shown in FIG.
In the i4 setting register 246, setting information [i4] of the output current value of the current source a243 is set.
In the i2 setting register 247, setting information [i2] of the output current value of the current source b244 is set.
In the i1 setting register 248, setting information [i1] of the output current value of the current source c245 is set.
The degree of modulation is changed according to the set current values i1, i2, and i4.

  The control unit 103 holds correspondence data between the determined communication rate and the setting information to be set in each of the registers 246 to 248 shown in FIG. 12, for example, table data, and the setting information i1, i2, i4 is stored in each register according to this data. Set.

A current source a243 shown in FIG. 12 inputs a 1/0 signal that is a transmission information signal (modulation signal) from a transmission information signal (modulation signal) input unit 251;
When the transmission information signal (modulation signal) = 1, the signal is turned on and the current value i4 is output.
When the transmission information signal (modulation signal) = 0, it is turned OFF and the output of the current value i4 is stopped.

Further, the current source b244 inputs OR operation results of the OR circuit 249 of each input of the transmission information signal (modulation signal) input unit 251 and the non-modulation / modulation setting signal input unit 254,
When the OR calculation result = 1, it is ON and the current value i2 is output.
When the OR operation result = 0, the output is turned OFF and the output of the current value i2 is stopped.
As shown in FIG. 13 (2), the non-modulation / modulation setting signal input unit 254 outputs [0] with the transmission interval of the transmission information as the modulation interval, and sets the non-transmission interval of the transmission information as the non-modulation interval. The signal is set to output [1].

The current source c245 is always ON and outputs a current value i1.
FIG. 13 shows an example of the signal waveform of each circuit unit shown in FIG.

FIG. 13 shows the following signal waveforms.
(1) Carrier signal (2) No modulation / modulation setting signal (3) Transmission information signal (modulated signal)
(4) Input signal (i5) of transistor (Q1) 241
(5) Input signal (i6) of transistor (Q2) 242
(6) Transmission signal (i3)

The transistor (Q1) 241 and the transistor (Q2) 242 illustrated in FIG. 12 constitute a differential amplifier circuit.
The carrier signal is input from the carrier signal input unit 252 to the transistor (Q1) 241, and the transistor (Q1) 241 is controlled to be turned on / off according to the 1/0 pattern of the carrier signal.
On the other hand, the carrier signal inversion signal is input from the carrier signal inversion signal input unit 253 to the transistor (Q2) 242, and the transistor (Q2) 242 is subjected to ON / OFF control according to the 1/0 pattern of the carrier signal inversion signal. Do.

As a result, the input signal waveform of the transistor (Q1) 241 is the signal waveform shown in FIG.
The input signal waveform of the transistor (Q2) 242 is the signal waveform shown in FIG.
The input signal waveform of the transistor (Q1) 241 and the input signal waveform of the transistor (Q2) 242 have opposite patterns.

In addition, the non-modulation period in which transmission of transmission information is stopped, that is,
In the interval of no modulation / modulation setting signal = 1 in FIG.
The current sources b and 244 are turned on.
Since the transmission information signal (modulation signal) of the current sources a and 243 is basically a transmission stop period, the value is 0.
Therefore, the input current of each transistor is
i1 + i2.

In addition, a modulation section in which transmission of transmission information is performed, that is,
In the interval of no modulation / modulation setting signal = 0 in FIG.
Both the current sources a and 243 and the current sources b and 244 are switched ON / OFF in synchronization with the value of the transmission information signal (modulation signal): 1/0.
Therefore, the input current of each transistor is
When transmission information signal (modulated signal) = 1,
i1 + i2 + i4.
When the transmission information signal (modulation signal) = 0, the input current of each transistor is
Set to i1.

A signal pattern corresponding to the variation of the transistor input current is a transmission signal (i3) as an output to the antenna circuit 102 shown in FIG. The signal waveform of the transmission signal is the waveform shown in FIG. 13 (6) transmission signal (i3).
The amplitudes of the transmission information signal (modulated signal) = 1 and 0 are set as follows.
When transmission information signal (modulated signal) = 1,
Amplitude i3 _max = ((2Z1) / (2Z1 + Z2)) (i1 + i2 + i4)
When transmission information signal (modulated signal) = 0,
Amplitude i3 _min = ((2Z1) / (2Z1 + Z2)) (i1)

The amplitude in the non-modulation section (no modulation / modulation setting signal = 1) is
Amplitude i3 _non = ((2Z1) / (2Z1 + Z2)) (i1 + i2)
It looks like this.

In the above formula, i1, i2, Z1, and Z2 are the following values.
i1: A value set in the i1 setting register 248 by the control unit 103, and a current value flowing through the current sources c and 245,
i2: a value set in the i2 setting register 247 by the control unit 103, the current flowing through the current sources b and 244,
i4: a value set in the i4 setting register 246 by the control unit 103, the current flowing through the current sources a and 243,
Z1: a load resistance Z1 connected to the supply voltage Vcc shown in FIG.
Z2: load resistance Z2 of the antenna circuit 102,
These values.

As described above, the degree of modulation is represented by the following equation, where a is a large amplitude value and b is a small amplitude value.
Modulation factor = (a−b) / (a + b) × 100 (%)
Therefore, the modulation degree of the transmission signal (i3) shown in FIG. 13 (6) is calculated by the following equation.
Modulation _{= (i3 max -i3 min) /} (i3 max + i3 min) × 100 (%)
= [((2Z1) / (2Z1 + Z2)). (I1 + i2 + i4-i1)] / [((2Z1) / (2Z1 + Z2)). (I1 + i2 + i4 + i1)]
= (I2 + i4) / (2i1 + i2 + i4)

Thus, the modulation degree is the setting information set according to the communication rate determined by the control unit 103, that is,
The set value [i1] of the i1 setting register 248 shown in FIG.
The set value [i2] of the i2 setting register 247 shown in FIG.
Setting value [i4] of the i4 setting register 246 shown in FIG.
The degree of modulation is determined by these values.
When the transmission rate is set high, the control unit 103 determines i1, i2, and i4 that increase the degree of modulation and sets them in each register.
Further, when the transmission rate is set to be low, the control unit 103 determines i1, i2, and i4 so that the degree of modulation becomes small and sets it in each register.

As described above, the control unit 103 should determine the maximum communication rate allowed by the communication partner apparatus (transponder) according to the result of, for example, test transmission, and set the transmission signal according to the determination information. The modulation degree is determined, and setting information [i1], [i2], and [i4] are set according to the determined modulation degree. The control unit 103 holds correspondence data between the communication rate to be set and the setting information, for example, table data, and inputs the setting information to the i1 setting register 248, the i2 setting register 247, and the i4 setting register 246 according to this data.
With such a configuration, it is possible to generate and output a transmission signal in which different modulation degrees are set according to the communication rate.

  Further, as understood from the transmission signal waveform shown in FIG. 13 (6), the amplitude of the non-modulation section (non-modulation / modulation setting signal = 1) is the same as the amplitude when the transmission information signal (modulation signal) = 1. , And the transmission information signal (modulation signal) = 0.

  Some communication devices such as an IC card used as a communication device on the data receiving side have a configuration that generates a power by receiving a carrier signal. When the amplitude of the carrier signal is reduced, a sufficient electromotive force cannot be obtained.

  In the configuration of the present embodiment, the amplitude of the non-modulation section (no modulation / modulation setting signal = 1), the amplitude when the transmission information signal (modulation signal) = 1, and the transmission information signal (modulation signal) = 0 Therefore, the average amplitude is almost uniform in both the non-modulation section (no modulation / modulation setting signal = 1) and the modulation section (no modulation / modulation setting signal = 0). Will be retained. Therefore, a stable electromotive force can be obtained from the carrier signal on the data receiving side.

[3-3. Third Embodiment of Transmission Signal Generation Unit]
Next, a third embodiment of the transmission signal generation unit will be described with reference to FIGS. 14, 15, and 16. FIG.
FIG. 14 is a diagram illustrating a specific circuit configuration example of the transmission signal generation unit 101 according to the third embodiment.
FIG. 15 is a diagram illustrating a detailed configuration of the current sources a to d and 301 to 304 in the transmission signal generation unit 101 illustrated in FIG. 14.
FIG. 16 is a diagram illustrating an example of a signal waveform of each unit in the transmission signal generation unit 101 illustrated in FIG.

  In the transmission signal generation unit 101 illustrated in FIG. 14, the first register 321, the second register 322, and the switch 323 illustrated in the lower stage correspond to the modulation degree setting information input unit 203 illustrated in FIG. 9. The upper circuit corresponds to a circuit in which the modulation unit 201 and the transmission amplifier 202 shown in FIG.

  The control unit 103 determines the maximum allowable communication rate of the communication partner acquired by the above-described test transmission process such as polling, and the first register 321 and the second register corresponding to the modulation degree setting information input unit 203 illustrated in FIG. A set value is input to 322, and control information for operating the switch 323 is output.

In the circuit configuration shown in FIG.
The current sources a and 301 to the current sources d and 304 constitute an H-bridge circuit and have a configuration for adjusting the transmission signal (ip, im) according to the current of each current source.
The signals of the carrier signal input unit 332 and the carrier signal inversion signal input unit 333 are input to each current source with the following settings.

A carrier signal from the carrier signal input unit 332 is input to the current sources c and 303.
An inverted signal of the carrier signal from the carrier signal input unit 332 is input to the current sources a and 301.
A carrier signal inversion signal from the carrier signal inversion signal input unit 333 is input to the current sources d and 304.
An inverted signal of the carrier signal inversion signal from the carrier signal inversion signal input unit 333 is input to the current sources b and 302.

As a result, when the carrier signal is “1”, the current sources b and 302 and the current sources c and 303 are turned on, and the current [ip] flows.
When the carrier signal is “0”, the current sources a and 301 and the current sources d and 304 are turned on, and the current [im] flows.
The currents [ip] and [im] are values that can be changed according to the set values of the first register 321 and the second register 322 and the settings of the current sources a to d and 301 to 304. These are used as amplitude setting information of the transmission signal.

The switch 323 is set to the s1 side when the transmission information signal (modulation signal) = 1, and is connected to the first register 321. When the transmission information signal (modulation signal) = 0, the switch 323 is set to the s2 side. Control is performed by the control unit 103 so as to connect to the register 322.
The first register 321 is a register for setting a value for determining a carrier current when the transmission information signal (modulation signal) = 1, and the second register 322 is a carrier when the transmission information signal (modulation signal) = 0. It is a register that sets a value that determines the current.

The detailed configuration of each of the current sources a to d and 301 to 304 will be described with reference to FIG.
The upper current source a301 and current source b302 in FIG. 14 have the configuration shown in FIG.
The current source c303 and current source d304 in the lower part of FIG. 14 have the configuration shown in FIG.

As shown in FIG. 15A, the current source a301 and the current source b302 have a plurality of input signals (in this example, an inverted signal of the carrier signal and an inverted signal of the set value of the first register 321 or the second register 322). It is composed of a plurality (five in this example) of CMOS transistors that perform current control according to the outputs of five (5) NAND circuits.
In addition, as shown in FIG. 15B, the current source c303 and the current source d304 have a plurality (five in this example) that receive a carrier signal and a signal of a set value of the first register 321 or the second register 322. ) Of a plurality of (5 in this example) CMOS transistors that perform current control according to the output of the AND circuit.

A combination of n (n = 5 in this example) CMOS transistors (ON / OFF) of the current sources a to d and 301 to 304 enables 2 ⁿ current settings in each current source. . The current flowing through the CMOS transistor is proportional to the size of the CMOS transistor, and can be set to a ratio of 0, 1, 2,..., 31 when n = 5, depending on the ON / OFF combination of the transistors.

This means that
Current ip when carrier signal = 1,
Current im when carrier signal = 0,
This means that this combination can be set to various combinations.

As a result, by using the transmission signal generation unit 101 shown in FIG.
When the transmission information is 1,
Current ip1 when carrier signal = 1
Current im1 when carrier signal = 0,
When the transmission information is 0,
Current ip0 when carrier signal = 1
Current im0 when carrier signal = 0,
This means that various settings of these signals are possible.

In FIG.
(1) Carrier signal,
(2) Transmission information signal (modulated signal),
(3) Transmission signal (im, ip),
Examples of these signal waveforms are shown.

(3) As shown in the figure, the transmission signal is
When the transmission information is 1,
Current ip1 when carrier signal = 1
Current im1 when carrier signal = 0,
When the transmission information is 0,
Current ip0 when carrier signal = 1
Current im0 when carrier signal = 0,
These four signal levels are set signals.

  As described above, these ip1, im1, ip0, and im0 can be set to various values according to the settings of the current sources and the set values of the first register 321 and the second register 322, and the degree of modulation can be freely set. Can be set.

For example, the control unit 103 determines the maximum communication rate allowed by the communication partner device (transponder) according to the result of test transmission or the like, and determines the modulation degree to be set in the transmission signal according to the determination information. Setting information corresponding to the modulation degree thus set is set in the first register 321 and the second register 322. The control unit 103 holds correspondence data between the communication rate to be set and the setting information, for example, table data, and sets the setting information in each register according to this data.
In the configuration shown in FIG.
In the first register 321, the current value setting information of the carrier signal when the transmission information signal (modulation signal) = 1 is set.
In the second register 322, the current value setting information of the carrier signal when the transmission information signal (modulation signal) = 0 is set.
With such a configuration, it is possible to generate and output a transmission signal in which different modulation degrees are set according to the communication rate.

[3-4. Embodiment 4 of Transmission Signal Generation Unit]
Next, a fourth embodiment of the transmission signal generation unit will be described with reference to FIGS.
FIG. 17 is a diagram illustrating a specific circuit configuration example of the transmission signal generation unit 101 according to the fourth embodiment.
FIG. 18 is a diagram illustrating an example of the signal waveform of each unit in the transmission signal generation unit 101 illustrated in FIG.

The configuration shown in FIG. 17 is similar to the third embodiment described with reference to FIG. 14, and the current sources a and 351 to the current sources d and 354 constitute an H-bridge circuit, depending on the current of each current source. The transmission signal (i) is adjusted.
The detailed configurations of the current sources a and 351 to the current sources d and 354 are the same as those of the current sources a and 301 to the current sources d and 304 of the third embodiment, and the current sources a and 351 and the current sources b and 352 are: The current sources c and 353 and the current sources d and 354 have the configuration shown in FIG. 15B.

The difference from the third embodiment described with reference to FIG. 14 is that a modulation / non-modulation setting signal input unit 334, a switch 365, and a third register 363 are added.
That is, the process at the time of transmission of the transmission information signal is such that the switch 365 is set to the left side (s1), and the process in this case is the same process as in the third embodiment.

  However, when the transmission information signal is not transmitted, the switch 365 is set to the right side (s2). In this case, as the set currents of the current sources a and 351 to the current sources d and 354, the set value of the third register 363, that is, the set value of the carrier current at the time of no modulation is provided.

As a result, by using the transmission signal generation unit 101 shown in FIG.
When the transmission information is 1,
Current ip1 when carrier signal = 1
Current im1 when carrier signal = 0,
When the transmission information is 0,
Current ip0 when carrier signal = 1
Current im0 when carrier signal = 0,
In addition to these signals,
Current ipn when carrier signal = 1 in case of setting that transmission information is not transmitted
Current imn when carrier signal = 0,
These six types of current can be set in various ways.

  These ip1, im1, ip0, im0, ipn, ipm can be set to various values depending on the setting of each current source and the setting values of the first register 361, the second register 362, and the third register 363. The degree can be set freely.

In FIG.
(1) Carrier signal,
(2) modulated / unmodulated signal,
(3) Transmission information signal (modulated signal),
(4) Transmission signal (im, ip),
Examples of these signal waveforms are shown.

(4) As shown in FIG.
When modulating (modulated / non-modulated signal = 1) and the transmission information is 1,
Current ip1 when carrier signal = 1
Current im1 when carrier signal = 0,
When modulating (modulated / non-modulated signal = 1) and transmission information is 0,
Current ip0 when carrier signal = 1
Current im0 when carrier signal = 0,
Furthermore, in the case of a setting in which transmission information is not transmitted as non-modulated (modulated / non-modulated signal = 0),
Current ipn when carrier signal = 1
Current imn when carrier signal = 0,
These six signal levels are set signals.

  As described above, ip1, im1, ip0, im0, ipn, and imn are set to various values depending on the setting of each current source and the setting values of the first register 361, the second register 362, and the third register 363. It is possible and the degree of modulation can be set freely.

For example, the control unit 103 determines the maximum communication rate allowed by the communication partner device (transponder) according to the result of test transmission or the like, and determines the modulation degree to be set in the transmission signal according to the determination information. Setting information corresponding to the modulated degree is set in the first register 361, the second register 362, and the third register 363. The control unit 103 holds correspondence data between the communication rate to be set and the setting information, for example, table data, and sets the setting information in each register according to this data.
In the configuration shown in FIG.
In the first register 361, current value setting information of the carrier signal when the transmission information signal (modulation signal) = 1 is set.
In the second register 362, the current value setting information of the carrier signal when the transmission information signal (modulation signal) = 0 is set.
In the third register 363, current value setting information of the carrier signal when transmission information is not transmitted is set.
With such a configuration, it is possible to generate and output a transmission signal in which different modulation degrees are set according to the communication rate.

  Further, as understood from the transmission signal waveform shown in FIG. 18 (4), the amplitude of the non-modulation section (non-modulation / modulation setting signal = 1) is the same as the amplitude when the transmission information signal (modulation signal) = 1. , And the transmission information signal (modulated signal) = 0.

  Some communication devices such as an IC card used as a communication device on the data receiving side have a configuration that generates a power by receiving a carrier signal. When the amplitude of the carrier signal is reduced, a sufficient electromotive force cannot be obtained.

  In the configuration of the present embodiment, the amplitude of the non-modulation section (no modulation / modulation setting signal = 1), the amplitude when the transmission information signal (modulation signal) = 1, and the transmission information signal (modulation signal) = 0 Therefore, the average amplitude is almost uniform in both the non-modulation section (no modulation / modulation setting signal = 1) and the modulation section (no modulation / modulation setting signal = 0). Will be retained. Therefore, a stable electromotive force can be obtained from the carrier signal on the data receiving side.

[4. Communication device that executes data transmission in load modulation]
The above-described embodiment is an embodiment in which the modulation degree is controlled in the modulation processing in the communication apparatus that performs data transmission by generating a transmission signal by refining the carrier signal and superimposing transmission information. Such communication is executed as processing on the reader / writer side in communication between the reader / writer and the silane responder (IC card or the like).

  On the other hand, when data is transmitted from a transponder such as an IC card to the reader / writer, data transmission by load modulation is executed. In this method, a carrier signal generated and transmitted by a reader / writer is received, and the received carrier signal is subjected to modulation processing by transmission information generated on the transponder side such as an IC card, that is, load modulation is performed.

  On the reader / writer side, the transponder (IC card) receives the modulation result data modulated by the transmission information (modulated signal) with respect to the carrier signal transmitted by itself, analyzes it, and transmits it from the transponder (IC card). Get information.

  Also in this load modulation processing, the above-described modulation degree control is possible. Hereinafter, an embodiment of the modulation degree control processing on the transponder side that performs data transmission by load modulation will be described.

[4-1. Example of modulation degree control in load modulation (Example 4)]
An embodiment (embodiment 4) of modulation degree control in load modulation will be described with reference to FIG.
FIG. 19 shows a configuration example of a communication apparatus (transponder) 500 that receives a carrier signal from the reader / writer 400 and performs data transmission by load modulation based on transmission information 550.

  The reader / writer 400 transmits a 13.56 MHz carrier signal to the communication device (transponder) 500. The communication device (transponder) 500 transmits a transmission signal generated by modulating transmission information in the range of, for example, 212 kbps to 3.14 Mbps to the reader / writer 400 via the antenna circuit 510.

  At this time, the communication device (transponder) 500 controls the modulation degree according to the communication rate (for example, 212 kbps to 3.14 Mbps) of communication to be executed. The control mode of the modulation degree is control that increases the modulation degree as the communication rate increases as in the above-described embodiment.

  As a means for controlling the degree of modulation, there is a method of adjusting the quality factor (Q) representing the sharpness of resonance described above with reference to FIG. FIG. 5 shows resonance characteristics when the quality factor (Q) representing the sharpness of resonance is 20. The spectrum decreases with increasing distance from the carrier frequency (13.56 MHz).

  When the quality factor (Q) is increased, the resonance frequency characteristic becomes steep near the carrier frequency (13.56 MHz), and when the quality factor (Q) is decreased, the frequency characteristic becomes gentle. Therefore, if the control for lowering the quality factor (Q) is performed, it is possible to prevent the spectrum from becoming extremely small even if it is far from the carrier frequency (13.56 MHz).

  For example, FIG. 6 shows a sideband spectrum modulated by a Manchester code with the resonance characteristic of Q = 20. As understood from FIG. 6, the spectrum of 3.4 Mbps is 19 dB lower than the regulation level. However, if the quality factor (Q) is lowered, the spectrum level can be prevented from being lowered even if the quality factor (Q) is far from the carrier frequency (13.56 MHz).

  The communication apparatus (transponder) 500 shown in FIG. 19 is configured to control the modulation factor by controlling the quality factor (Q) based on such a theory.

  An antenna circuit 501 serving as a data transmission / reception unit in the communication device (transponder) 500 illustrated in FIG. 19 includes a coil (L), a resonance capacitor (C), and a resistor (R0).

In the circuit of this data transmitter / receiver 110,
The resonance frequency of the antenna can be expressed by the following formula (Formula 1).

... (Formula 1)

In the above formula (formula 1), since the inductance L is uniquely determined by the coil (L), the resonance frequency f ₀ is determined by changing the value of C. As described above, in order to perform communication with the carrier frequency set to 13.56 MHz, f ₀ is adjusted to 13.56 MHz. That is, L and C are determined as one design value.

  The Q value (quality factor) of the antenna circuit 501 shown in FIG. 19 can be calculated by the following equation (equation 2).

... (Formula 2)

Since the inductance L is that determined are determined by the coil (L), f ₀ also, for example, as described above 13.56MHz such as, Q value by varying the capacitance C or resistance R, (quality factor) Can be adjusted.

For example, if you want to adjust to Q = 20, substitute Q = 20 into the above equation (Equation 2),
R = (1/10) πf ₀ L
May be set as the resistance value of the resistor (R0).

  A communication device (transponder) 500 shown in FIG. 19 has a configuration in which a plurality of resistors R1, 511 to R3, 513 are connected to an antenna circuit in order to adjust a Q value (quality factor). In addition, transistors Q1, 521 to Q3, 523 for current control with respect to this resistor are arranged.

  Each of the transistors Q1, 521 to Q3, 523 can be controlled by the switches SW1, 531 to SW3, 533 of the switch circuit 503.

The switches SW1, 531 to SW3, 533 of the switch circuit 503 are controlled by the control unit 502.
For example, the control unit 502 acquires communication information with the reader / writer 400 detected by the reception signal detection unit 501 and performs control according to a communication rate determined with the reader / writer 400 (for example, a range of 212 Kbps to 3.4 Mbps). Execute. The control unit 502 controls the switches SW1, 531 to SW3, 533 of the switch circuit 503 to change the Q value in order to control the modulation degree according to the determined communication rate.

The resistance value of the antenna circuit is changed by ON / OFF setting of the switches SW1 to SW3 shown in FIG. 19, and as a result, the Q value (quality factor) is controlled.
A specific example of a change in the resistance value of the antenna circuit due to the ON / OFF setting of the switches SW1 to SW3 is shown in FIG.

As shown in FIG. 20A, there are eight combinations of N / OFF settings of the three switches SW1 to SW3.
For example, assume that the resistance value of each resistor is set as follows.
R0 = 2kΩ
R1 = 4kΩ
R2 = 2kΩ
R3 = 1kΩ

In this case, the combined resistance value of the antenna circuit is as shown in FIG.
From 2kΩ when all switches are OFF,
0.44kΩ when all switches are ON,
These eight types of modes can be set.
FIG. 20B is a graph showing the change in the combined resistance value.

  The control unit 502 holds, as a table, correspondence data between, for example, a communication rate and a switch setting mode (modes (modes 1 to 8 shown in FIG. 20)) for setting a Q value necessary for optimal modulation degree setting. In accordance with the table data, the optimum mode for the determined communication rate is selected, and the switch control is executed according to the selected mode.

  The Q value is controlled by this switch control, and as a result, a transmission signal (load modulation signal) having a modulation degree optimum for the communication rate is generated and transmitted to the reader / writer 400.

[4-2. Example of modulation degree control in load modulation (Example 5)]
Next, an example (Example 5) of modulation degree control in load modulation will be described with reference to FIG.

  FIG. 21 shows a configuration example of a communication device (transponder) 600 that receives a carrier signal from the reader / writer 400 and performs data transmission by load modulation based on transmission information 620.

  The reader / writer 400 transmits a 13.56 MHz carrier signal to the communication device (transponder) 600. The communication device (transponder) 600 transmits a transmission signal generated by modulating transmission information in a range of, for example, 212 kbps to 3.14 Mbps to the reader / writer 400 via the antenna circuit 601.

  At this time, the communication device (transponder) 600 controls the modulation degree according to the communication rate (for example, 212 kbps to 3.14 Mbps) of communication to be executed. The control mode of the modulation degree is control that increases the modulation degree as the communication rate increases as in the above-described embodiment.

A communication apparatus (transponder) 600 illustrated in FIG. 21 has a configuration in which a current control circuit 610 controls a current flowing through the antenna circuit 601.
The current control circuit 610 has a function of adjusting the current when the transmission information is 1 and the current when the transmission information is 0. This directly controls the degree of modulation.

The current control circuit 610 is configured by a combination circuit of a plurality of CMOS transistors 612a to 612e and switches 611a to 611e that control currents flowing through these CMOS transistors 612a to 612e. In the example shown in the figure, the configuration has five CMOS transistors, but this number can be variously set.
The resistance at the time of saturation of the CMOS transistors 612a to 612e is inversely proportional to the size of the CMOS transistor. Depending on the combination of ON / OFF of the transistors, load modulation processing with various modulation degrees can be performed by changing the resonance Q.

When the transmission information 620 is 0, the current according to the set value of the first register 604 is controlled by the switch setting of the current control circuit 610 and supplied to the antenna circuit 601.
When the transmission information 620 is 1, the current according to the setting value of the second register 605 is controlled by the switch setting of the current control circuit 610 and supplied to the antenna circuit 601.

  For example, the control unit 603 acquires communication information with the reader / writer 400 detected by the received signal detection unit 602, and performs control according to the communication rate determined with the reader / writer 400 (for example, a range of 212 Kbps to 3.4 Mbps). Execute. The control unit 603 sets values in the first register 604 and the second register 605 in order to adjust the modulation degree according to the determined communication rate, and further switches the current control circuit 610.

  Note that each register setting value for setting the modulation degree according to the communication rate and the setting information of the current control circuit 610 are determined based on data measured in advance, and are held as table data, for example. The control unit 603 acquires setting information from the table according to the determined communication rate, sets values in the first register 604 and the second register 605, and further switches the current control circuit 610.

This control causes the antenna circuit 601 to flow.
Current I1 when the transmission information is 1,
Current I0 when transmission information is 0,
Can be freely controlled, and a transmission signal in which the degree of modulation is controlled can be generated. As a result, it is possible to provide the reader / writer 400 with a transmission signal (load modulation signal) in which an optimum modulation degree is set for the communication rate.

  Note that the first register that stores the adjustment value of the current value when the transmission information shown in FIG. 21 is 0 may be set to all zeros. Alternatively, it may be omitted. In this case, only the current I1 when the transmission information is 1 is adjusted. Even with such a configuration, the modulation degree can be adjusted.

[4-3. Example of modulation degree control in load modulation (Example 6)]
Next, an example (Example 6) of modulation degree control in load modulation will be described with reference to FIG.

  FIG. 22 shows a configuration example of a communication device (transponder) 700 that receives a carrier signal from the reader / writer 400 and performs data transmission by load modulation based on transmission information 720.

  The reader / writer 400 transmits a 13.56 MHz carrier signal to the communication device (transponder) 700. The communication device (transponder) 700 transmits a transmission signal generated by modulating transmission information in a range of, for example, 212 kbps to 3.14 Mbps to the reader / writer 400 via the antenna circuit 601.

  At this time, the communication apparatus (transponder) 700 controls the modulation degree according to the communication rate (for example, 212 kbps to 3.14 Mbps) of communication to be executed. The control mode of the modulation degree is control that increases the modulation degree as the communication rate increases as in the above-described embodiment.

The communication device (transponder) 700 shown in FIG. 22 has a configuration in which the current control circuit 710 controls the current flowing through the antenna circuit 701 as in the previous embodiment described with reference to FIG.
The current control circuit 710 has a function of adjusting a current when the transmission information is 0 and a current when the transmission information is 1. This directly controls the degree of modulation.

  The current control circuit 710 is composed of a combination circuit of a plurality of CMOS transistors and a switch for controlling a current flowing through these CMOS transistors. In the example shown in the figure, the configuration has 10 CMOS transistors.

When the transmission information 720 is 0, the current according to the set value of the first register 704 is controlled by the switch setting of the current control circuit 710 and supplied to the antenna circuit 701.
When the transmission information 720 is 1, the current according to the set value of the second register 705 is controlled by the switch setting of the current control circuit 710 and supplied to the antenna circuit 701.

  For example, the control unit 703 acquires communication information with the reader / writer 400 detected by the reception signal detection unit 702, and performs control according to the communication rate determined with the reader / writer 400 (for example, a range of 212 Kbps to 3.4 Mbps). Execute. The control unit 703 sets values in the first register 704 and the second register 705 in order to adjust the modulation degree according to the determined communication rate, and further switches the current control circuit 710.

  Note that each register setting value for setting the modulation degree according to the communication rate and the setting information of the current control circuit 710 are determined based on data measured in advance, and are held as table data, for example. The control unit 703 acquires setting information from the table according to the determined communication rate, sets values in the first register 704 and the second register 705, and further switches the current control circuit 710.

This control causes the antenna circuit 701 to flow.
Current I1 when the transmission information is 1,
Current I0 when transmission information is 0,
Can be freely controlled, and a transmission signal in which the degree of modulation is controlled can be generated. As a result, it is possible to provide the reader / writer 400 with a transmission signal (load modulation signal) in which an optimum modulation degree is set for the communication rate.

  The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiments without departing from the gist of the present invention. In other words, the present invention has been disclosed in the form of exemplification, and should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims should be taken into consideration.

  The series of processing described in the specification can be executed by hardware, software, or a combined configuration of both. When executing processing by software, the program recording the processing sequence is installed in a memory in a computer incorporated in dedicated hardware and executed, or the program is executed on a general-purpose computer capable of executing various processing. It can be installed and run.

  As described above, according to the configuration of the embodiment of the present invention, the transmission signal generation unit that generates the transmission signal by performing the modulation process of superimposing the transmission information on the carrier signal by amplitude modulation, and the transmission signal In a communication apparatus having a control unit that performs control of the generation unit, the control unit performs control to cause the transmission signal generation unit to perform modulation processing with different modulation degrees according to the communication rate, and the transmission signal generation unit In accordance with the control, a transmission signal is generated by performing modulation processing with different modulation degrees according to the communication rate. Specifically, a transmission signal is generated by executing a modulation process in which the modulation degree is increased as the communication rate is increased. With this configuration, it is possible to improve the magnetic field strength level in the vicinity of the sideband particularly during high-speed communication, and good communication is realized.

DESCRIPTION OF SYMBOLS 10 Reader / Writer 11 Gain switching amplifier 12 Modulation part 13 Transmission amplifier 14 Antenna circuit 20 Transponder 21 Detection circuit 100 Communication apparatus 101 Transmission signal generation part 102 Antenna circuit 103 Control part 104 Reception signal detection part 121 Transmission information 122 Carrier signal 201 Modulation part 202 Transmission amplifier 203 Modulation degree setting information input unit 221, 222 Transistor 223, 224 Current source 225, 226 Register 241, 242 Transistor 243, 244, 245 Current source 246, 247, 248 Register 301 to 304 Current source 321, 322 Register 323 Switch 351-354 Current source 361-363 Register 365, 366 Switch 400 Reader / writer 500 Communication device (transponder)
501 Control unit 502 Reception signal detection unit 503 Switch circuit 510 Antenna circuit 511 to 513 Resistance 521 to 523 Transistor 531 to 533 Switch 550 Transmission information 600 Communication device (transponder)
601 Antenna circuit 602 Received signal detection unit 603 Control unit 604 to 605 Register 610 Current control circuit 611 Switch 612 CMOS transistor 620 Transmission information 700 Communication device (transponder)
701 Antenna circuit 702 Received signal detection unit 703 Control unit 704 to 705 Register 710 Current control circuit 720 Transmission information

Claims (15)

A transmission signal generation unit that generates a transmission signal by performing modulation processing for superimposing transmission information on the carrier signal by amplitude modulation;
A control unit that executes control of the transmission signal generation unit;
The controller is
Performing control to cause the transmission signal generation unit to perform modulation processing of different modulation degrees according to the communication rate,
The transmission signal generator is
A communication apparatus that generates a transmission signal by executing modulation processing with different modulation degrees according to a communication rate according to the control of the control unit. The controller is
Performing control to cause the transmission signal generation unit to perform modulation processing that increases the modulation degree as the communication rate increases,
The transmission signal generator is
The communication apparatus according to claim 1, wherein a transmission signal is generated by executing a modulation process in which a modulation degree is increased as a communication rate is increased under the control of the control unit. The controller is
The communication apparatus according to claim 1 or 2, wherein amplitude information of transmission signals corresponding to 0 and 1 of the transmission information is provided to the transmission signal generation unit. The control unit further includes:
The communication device according to claim 3, wherein amplitude setting information of a transmission signal at the time of no modulation is provided to the transmission signal generation unit. The controller is
5. The communication apparatus according to claim 4, wherein amplitude setting information for setting an amplitude of a transmission signal at the time of non-modulation between amplitudes of transmission signals corresponding to 0 and 1 of the transmission information is provided to the transmission signal generation unit. . The transmission signal generator is
A register for storing amplitude setting information provided by the control unit;
A current source for generating a current corresponding to a value stored in the register;
The communication device according to claim 3, wherein current control of the current source is executed according to a value of transmission information to generate a transmission signal in which a different amplitude is set according to the value of the transmission information. The transmission signal generator is
The communication apparatus according to claim 6, wherein transmission signal generation processing using a differential amplifier circuit is executed. The transmission signal generator is
The communication apparatus according to claim 6, wherein transmission signal generation processing using an H bridge circuit is executed. A control unit that executes control of load modulation for superimposing transmission information by amplitude modulation on a reception carrier signal;
The controller is
A communication device that executes modulation processing set to a different modulation degree according to a communication rate. The controller is
The communication apparatus according to claim 9, wherein modulation processing is performed in which a modulation degree is increased as a communication rate is increased. The controller is
The communication device according to claim 9 or 10, wherein processing for adjusting a Q value (quality factor) of an antenna circuit that outputs the transmission information according to a communication rate is performed. The controller is
The communication apparatus according to claim 11, wherein a process of adjusting a resistance value of an antenna circuit that outputs the transmission information according to a communication rate is performed. The controller is
The communication device according to claim 9 or 10, wherein a process for controlling a current value flowing in an antenna circuit that outputs the transmission information according to a communication rate is performed. The controller is
The communication apparatus according to claim 13, wherein a process for controlling a current value flowing in an antenna circuit that outputs the transmission information according to a value of the transmission information is performed. A communication control method executed in a communication device,
A step of executing control for causing the transmission signal generation unit to perform modulation processing of different modulation degrees according to a communication rate;
When the transmission signal generation unit performs a modulation process for superimposing transmission information on the carrier signal by amplitude modulation, the transmission signal is generated by performing a modulation process with a different modulation degree according to the communication rate according to the control of the control unit. A step of generating
A communication control method.