WO2020250309A1 - Error detection circuit - Google Patents

Error detection circuit Download PDF

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Publication number
WO2020250309A1
WO2020250309A1 PCT/JP2019/023144 JP2019023144W WO2020250309A1 WO 2020250309 A1 WO2020250309 A1 WO 2020250309A1 JP 2019023144 W JP2019023144 W JP 2019023144W WO 2020250309 A1 WO2020250309 A1 WO 2020250309A1
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Prior art keywords
voltage
output
code
converter
value
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PCT/JP2019/023144
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French (fr)
Japanese (ja)
Inventor
浩之 水谷
平 和田
龍也 上村
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三菱電機株式会社
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to JP2021525445A priority Critical patent/JP6945770B2/en
Priority to PCT/JP2019/023144 priority patent/WO2020250309A1/en
Publication of WO2020250309A1 publication Critical patent/WO2020250309A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/40—Means for monitoring or calibrating

Definitions

  • the present invention relates to an error detection circuit.
  • the D / A converter outputs the analog voltage corresponding to the input digital code.
  • the D / A converter is arranged between, for example, a control device provided with a processing circuit such as a microcomputer and outputting a digital signal, and a controlled object controlled by an analog voltage.
  • the D / A converter is arranged between the control device and the control target, and by connecting to the control device and the control target, the control device controls the control target via the D / A converter. be able to.
  • the analog voltage output from the D / A converter indicates a discrete voltage value corresponding to the digital code.
  • the interval between the discrete voltage values of the analog voltage output from the D / A converter is ideally a constant interval.
  • the D / A converter can output a voltage value of 8 steps corresponding to 2 to the 3rd power as an analog voltage.
  • the resolution of the D / A converter is 3 bits and the reference voltage input to the D / A converter is 5 volts (hereinafter referred to as "V"), the output is from the D / A converter.
  • the ideal voltage value interval of the analog voltage to be generated is 0.625V interval obtained by dividing 5V by 8.
  • Patent Document 1 discloses a radar device including a voltage controlled oscillator to which a D / A converter is applied as a control target.
  • the radar device outputs a signal in which the frequency of the output signal is changed linearly with time.
  • the radar device can measure the distance, the relative speed, etc. with higher accuracy as the linearity of the frequency changed with respect to time in the output signal is higher.
  • the analog voltage output by the D / A converter includes DNL
  • an analog voltage different from the desired control voltage by the amount of DNL is input to the voltage controlled oscillator. Therefore, the linearity of the frequency changed with respect to time in the signal output by the radar device deteriorates, and as a result, the accuracy of the distance or relative velocity measured by the radar device deteriorates.
  • the radar device described in Patent Document 1 measures the voltage value of the analog voltage output by the D / A converter with a voltmeter configured by the A / D converter, and measures the measured voltage value and a desired voltage. DNL is detected by comparing with the value.
  • the A / D converter outputs a digital code corresponding to the input analog voltage. Since the A / D converter converts a continuous analog voltage into a discrete digital code, the voltage value of the analog voltage input to the A / D converter is determined by the resolution of the A / D converter. If it is within the range of the voltage value of, the voltage value of the analog voltage input to the A / D converter is converted into the same digital code. Therefore, when the analog voltage output by the D / A converter is directly input to the A / D converter as in the radar device described in Patent Document 1, the DNL of the analog voltage output by the D / A converter is used.
  • the A / D converter is required to be an A / D converter having a resolution higher than that of the D / A converter in order to accurately detect the above.
  • the resolution of the A / D converter is limited, if the A / D converter does not have a resolution that satisfies the accuracy of the DNL to be detected, the DNL cannot be obtained with a desired detection accuracy.
  • the present invention is for solving the above-mentioned problems, and even if the A / D converter does not have high resolution, it is included in the interval between the voltage values of the analog voltage output by the D / A converter. It is an object of the present invention to provide an error detection circuit capable of detecting a DNL with high accuracy.
  • the error detection circuit receives a code output unit that outputs a first digital code indicating an output voltage value and a first digital code output by the code output unit, and outputs an analog voltage corresponding to the first digital code.
  • An output D / A converter a control output unit that outputs a control signal, a voltage source that receives the control signal output by the control output unit and outputs a reference voltage corresponding to the control signal, and a D / A converter.
  • a differential amplifier that receives the analog voltage output by and the reference voltage output by the voltage source, amplifies the difference voltage between the analog voltage and the reference voltage, and outputs the amplified difference voltage.
  • the A / D converter that outputs the second digital code corresponding to the differential voltage after amplification and the second digital code output by the A / D converter are received and the second digital code is received. It has a second digital code corresponding to the first analog voltage output by the D / A converter corresponding to the first digital code having one code value, and a second code value which is a value adjacent to the first code value.
  • the first analog voltage and the second analog voltage output by the D / A converter are based on the second digital code corresponding to the second analog voltage output by the D / A converter corresponding to the first digital code.
  • the voltage difference calculation unit that calculates the voltage difference of the above as the output voltage difference, the output voltage value indicated by the first digital code having the first code value, and the output voltage value indicated by the first digital code having the second code value.
  • the control output unit includes a first digital code in which the voltage difference calculation unit has a first code value, and includes an error calculation unit that calculates an error of the output voltage difference calculated by the voltage difference calculation unit based on the voltage difference. It is configured to output a control signal that keeps the reference voltage output by the voltage source constant in the period until the second digital code corresponding to the above and the second digital code corresponding to the second code value are received.
  • an A / D converter that does not have a high resolution can detect DNL included in the interval of the voltage value of the analog voltage output by the D / A converter with high accuracy.
  • FIG. 1 is a block diagram showing an example of the configuration of a main part of the error detection circuit according to the first embodiment.
  • FIG. 2 is a diagram showing a time change of a voltage value of an analog voltage output by a D / A converter in the error detection circuit according to the first embodiment and a voltage value of a reference voltage output by a voltage source.
  • FIG. 3 is a diagram showing an example of a time change of the voltage value of the amplification difference voltage output by the differential amplifier in the error detection circuit according to the first embodiment.
  • Embodiment 1 The error detection circuit 100 according to the first embodiment will be described with reference to FIGS. 1 to 3.
  • FIG. 1 is a block diagram showing an example of the configuration of a main part of the error detection circuit 100 according to the first embodiment.
  • the error detection circuit 100 includes a code output unit 110, a D / A converter 120, a control output unit 130, a voltage source 140, a differential amplifier 150, an A / D converter 160, a voltage difference calculation unit 170, and an error calculation unit 180. And an output terminal 199.
  • the error detection circuit 100 may include a low-pass filter 190 in addition to the above configuration.
  • FIG. 1 is a block diagram showing an example of the configuration of a main part of the error detection circuit 100 according to the first embodiment.
  • the error detection circuit 100 includes a code output unit 110, a D / A converter 120, a control output unit 130, a voltage source 140, a differential amplifier 150, an A / D converter 160, a voltage difference calculation unit 170, and an error calculation unit 180. And an output terminal 199.
  • the error detection circuit 100 may include a low-pass filter 190 in
  • the error detection circuit 100 includes a code output unit 110, a D / A converter 120, a control output unit 130, a voltage source 140, a differential amplifier 150, an A / D converter 160, a voltage difference calculation unit 170, and an error.
  • the one provided with the calculation unit 180, the output terminal 199, and the low-pass filter 190 is shown.
  • the code output unit 110 outputs a first digital code indicating an output voltage value.
  • the D / A converter 120 receives the first digital code output by the code output unit 110 and outputs an analog voltage corresponding to the first digital code. Specifically, the D / A converter 120 outputs an analog voltage having a voltage value corresponding to the first digital code among a plurality of discrete voltage values. As shown in FIG. 1, when the error detection circuit 100 includes a low-pass filter 190, the D / A converter 120 outputs an analog voltage to the output terminal 199 and the differential amplifier 150 via the low-pass filter 190.
  • the output terminal 199 is a terminal for connecting a control target (not shown) and the D / A converter 120.
  • the control target receives the analog voltage output by the D / A converter 120 and is controlled by the analog voltage.
  • the low-pass filter 190 receives the analog voltage output by the D / A converter 120 and attenuates the analog voltage of the frequency component higher than the predetermined cutoff frequency among the analog voltage, and the frequency component lower than the cutoff frequency. Pass the analog voltage of.
  • the control output unit 130 outputs a control signal to the voltage source 140. Specifically, for example, the control output unit 130 outputs a control signal corresponding to the first digital code output by the code output unit 110 to the voltage source 140.
  • the voltage source 140 receives the control signal output by the control output unit 130 and outputs a reference voltage corresponding to the control signal to the differential amplifier 150. Specifically, for example, the voltage source 140 outputs a reference voltage corresponding to the output voltage value indicated by the first digital code corresponding to the control signal to the differential amplifier 150.
  • the value corresponding to the output voltage value indicated by the first digital code is, for example, a voltage value substantially equal to the output voltage value indicated by the first digital code, and is substantially equal to the ideal voltage value indicated by the first digital code. Equal voltage values.
  • the voltage source 140 is composed of, for example, a second D / A converter different from the D / A converter 120 that outputs an analog voltage corresponding to the first digital code described above.
  • the voltage source 140 will be described as being configured by the second D / A converter, but the voltage source 140 may be configured by a general-purpose DC power supply.
  • the differential amplifier 150 has two input terminals, one input terminal is input with an analog voltage output by the D / A converter 120, and the other input terminal is a reference voltage output by the voltage source 140.
  • the voltage is input.
  • the differential amplifier 150 receives the analog voltage output by the D / A converter 120 and the reference voltage output by the voltage source 140, amplifies the difference voltage between the analog voltage and the reference voltage, and the difference after amplification.
  • the voltage is output to the A / D converter 160.
  • the A / D converter 160 receives the amplified difference voltage output by the differential amplifier 150 and outputs a second digital code corresponding to the amplified difference voltage to the voltage difference calculation unit 170.
  • the error detection circuit 100 according to the first embodiment will be described as including the A / D converter 160, but the error detection circuit 100 uses a general-purpose voltmeter (not shown) in place of the A / D converter 160. It may be provided.
  • the voltage difference calculation unit 170 receives the second digital code output by the A / D converter 160. More specifically, the voltage difference calculation unit 170 receives the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value. Further, the voltage difference calculation unit 170 corresponds to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is a value adjacent to the first code value. 2 Receive a digital code.
  • the value adjacent to the first code value is the discrete voltage value of the analog voltage output by the D / A converter 120 corresponding to the first digital code
  • the D / A converter 120 is the first. It is the value of the first digital code for the D / A converter 120 to output the analog voltage of the voltage value adjacent to the voltage value of the analog voltage output corresponding to the first digital code having one code value. More specifically, for example, the D / A converter 120 outputs an analog voltage having discrete voltage values at intervals of 0.625 V corresponding to the first digital code, and D / A conversion.
  • the D / A converter 120 When the device 120 outputs an analog signal having a voltage value of 2.5V when receiving the first digital code having the first code value, the D / A converter 120 has a value adjacent to the first code value.
  • the voltage difference calculation unit 170 is adjacent to the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value and the first code value.
  • the D / A converter 120 outputs based on the second digital code corresponding to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is the value.
  • the voltage difference between the first analog voltage and the second analog voltage is calculated as the output voltage difference. More specifically, the voltage difference calculation unit 170 is based on the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value. , Acquires the voltage value indicated by the second digital code.
  • the voltage difference calculation unit 170 calculates the difference between the two acquired voltage values, and uses the voltage difference between the first analog voltage and the second analog voltage output by the D / A converter 120 as the output voltage difference. calculate.
  • the error calculation unit 180 is a voltage difference calculation unit based on the voltage difference between the output voltage value indicated by the first digital code having the first code value and the output voltage value indicated by the first digital code having the second code value. The error of the output voltage difference calculated by 170 is calculated.
  • the error calculation unit 180 acquires the first digital code from the code output unit 110, and acquires the output voltage value indicated by the first digital code based on the acquired first digital code. More specifically, the error calculation unit 180 acquires the output voltage value indicated by the first digital code having the first code value based on the acquired first digital code having the first code value. Further, the error calculation unit 180 acquires the output voltage value indicated by the first digital code having the second code value based on the acquired first digital code having the second code value. The error calculation unit 180 calculates the difference between the two acquired voltage values so that the output voltage value indicated by the first digital code having the first code value and the first digital code having the second code value can be obtained. Calculate the voltage difference from the indicated output voltage value.
  • the error calculation unit 180 is a voltage difference calculation unit and a voltage difference between the output voltage value indicated by the first digital code having the calculated first code value and the output voltage value indicated by the first digital code having the second code value. By comparing with the output voltage difference calculated by 170, the error of the output voltage difference calculated by the voltage difference calculation unit 170 is calculated.
  • the control output unit 130 is in the period until the voltage difference calculation unit 170 receives the second digital code corresponding to the first digital code having the first code value and the second digital code corresponding to the second code value. , Outputs a control signal that keeps the reference voltage output by the voltage source 140 constant.
  • the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 are composed of a computer (not shown) such as a microcomputer.
  • the computer includes a processor (not shown) composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a microprocessor, a microcontroller, or a DSP (Digital Signal Processor), a RAM (Radom Access Memory), and a ROM. (Read-Only Memory), flash memory, EEPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Erasableprogrammable Read-Only Memory, Memory Hide ), Etc. It has a memory (not shown) composed of a magnetic disk or the like such as a semiconductor memory.
  • a program for making the computer function as a code output unit 110, a control output unit 130, a voltage difference calculation unit 170, and an error calculation unit 180 is stored in the memory.
  • the processor reads and executes the program stored in the memory, the functions of the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 are realized.
  • the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 include an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), an FPGA (Field-Programmable), and an FPGA (Field-Programmable). It may be configured by a processing circuit (not shown) such as (System-on-a-Chip) or a system LSI (Lage-Scale Integrated Circuit). Further, the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 are among the functions of the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180. A part of the functions may be realized by the processor and the memory, and the remaining functions may be realized by the processing circuit.
  • a part of the functions may be realized by the processor and the memory, and the remaining functions may be realized by the processing circuit.
  • FIG. 2 is a diagram showing a time change of the voltage value of the analog voltage output by the D / A converter 120 in the error detection circuit 100 according to the first embodiment and the voltage value of the reference voltage output by the voltage source 140. is there.
  • the horizontal axis represents time and the vertical axis represents voltage value.
  • the thin solid line shows the time change of the voltage value of the analog voltage output by the D / A converter 120
  • the thick solid line shows the time change of the voltage value of the reference voltage output by the voltage source 140.
  • the broken line is the time change of the voltage value of the analog voltage when the analog voltage output by the D / A converter 120 outputs an ideal analog voltage that does not include DNL.
  • FIG. 2 shows, as an example, a case where the first digital code output from the code output unit 110 has an arbitrary code value composed of N (N is a natural number of 1 or more) bits. That is, FIG. 2 shows a case where the first digital code output from the code output unit 110 has an arbitrary value from 0 to 2 N -1 as a code value.
  • the code output unit 110 sequentially outputs the first digital code having a code value from 0 to 2 N -1.
  • the code output unit 110 is first so that the code values of the first digital code are in the order of 0, 1, 2, ..., 2 N- 2,2 N -1. It will be described as outputting a digital code.
  • the order of the first code value of the digital code encoding output unit 110 outputs 0, 1, 2, ... is not limited to 2 N -2, 2 N -1, for example, 2 N -1, The order may be 2N- 2, ..., 2,1,0.
  • the D / A converter 120 When the first digital code is output from the code output unit 110, the D / A converter 120 that has received the first digital code outputs an analog voltage having a voltage value corresponding to the first digital code.
  • the DNL included in the analog voltage output by the D / A converter 120 is the analog voltage output by the D / A converter 120 when the D / A converter 120 receives the first digital code having the first code value.
  • the voltage value of the analog voltage output by the D / A converter 120 when the D / A converter 120 receives the first digital code having the second code value adjacent to the first code value. Obtained by using.
  • the first code value is n (n is a natural number of 0 or more and 2 N -2 or less) and the second code value is n + 1 will be described.
  • the code output unit 110 outputs the first digital code having the code value n to the D / A converter 120 during the period a shown in FIG. Specifically, for example, the code output unit 110 outputs a first digital code having a code value of n at the beginning of the period a shown in FIG. The time point at which the code output unit 110 outputs the first digital code whose code value is n may be before the start of the period a.
  • the D / A converter 120 receives the first digital code having a code value of n, and transfers the analog voltage of the voltage value corresponding to the first digital code, that is, the above-mentioned first analog voltage to the differential amplifier 150. Output.
  • the first analog voltage output from the D / A converter 120 contains an error with respect to a desired voltage value, that is, an ideal voltage value.
  • a desired voltage value that is, an ideal voltage value.
  • the voltage value of the analog voltage output when the D / A converter 120 receives the first digital code having the code value n is expressed as Vout [n], and is a desired voltage value which is an ideal voltage value.
  • the voltage value is expressed as Digital [n].
  • the control output unit 130 outputs a control signal to the voltage source 140 during the period a shown in FIG.
  • the code output unit 110 outputs a control signal at the beginning of the period a shown in FIG.
  • the time point at which the code output unit 110 outputs the control signal may be before the start of the period a.
  • the voltage source 140 receives the control signal output by the control output unit 130, and outputs the reference voltage of the voltage value corresponding to the control signal to the differential amplifier 150 in the period a shown in FIG. It is desirable that the control signal output by the control output unit 130 is selected so that the reference voltage having a voltage value close to the voltage value of the analog voltage output from the D / A converter 120 is output from the voltage source 140.
  • control output unit 130 receives the first digital code output by the code output unit 110 and outputs the reference voltage of the voltage value corresponding to the first digital code to D / D the voltage value of the reference voltage.
  • the voltage value can be set to be close to the voltage value of the analog voltage output from the A converter 120.
  • Vref [n] the voltage value of the reference voltage output when the voltage source 140 receives the first digital code whose code value is n.
  • the differential amplifier 150 receives an analog voltage whose voltage value output from the D / A converter 120 is Vout [n] and a reference voltage whose voltage value output from the voltage source 140 is Vref [n]. , The difference voltage between the analog voltage and the reference voltage is amplified, and the amplified difference voltage (hereinafter referred to as “amplification difference voltage”) is output to the A / D converter 160.
  • amplification difference voltage the amplified difference voltage
  • the A / D converter 160 receives the amplification difference voltage whose voltage value output by the differential amplifier 150 is Vamp [n], and the second digital code corresponding to the amplification difference voltage whose voltage value is Vamp [n]. Is output to the voltage difference calculation unit 170.
  • the voltage difference calculation unit 170 receives the second digital code corresponding to Vamp [n] and acquires the value of Vamp [n] by acquiring the voltage value corresponding to the second digital code.
  • the code output unit 110 outputs the first digital code having the code value n + 1 to the D / A converter 120 in the period b shown in FIG. Specifically, for example, the code output unit 110 outputs a first digital code having a code value of n + 1 at the beginning of the period b shown in FIG.
  • the D / A converter 120 receives the first digital code whose code value is n + 1, and transfers the analog voltage of the voltage value corresponding to the first digital code, that is, the above-mentioned second analog voltage to the differential amplifier 150. Output.
  • the second analog voltage output from the D / A converter 120 contains an error with respect to a desired voltage value, that is, an ideal voltage value.
  • the voltage value of the analog voltage output when the D / A converter 120 receives the first digital code whose code value is n + 1 is expressed as Vout [n + 1], and is a desired voltage value which is an ideal voltage value.
  • the voltage value is expressed as Digital [n + 1].
  • the voltage source 140 outputs a reference voltage having a voltage value equal to the voltage value output in the period a shown in FIG. 2 to the differential amplifier 150 in the period b shown in FIG. That is, the voltage source 140 outputs a reference voltage whose voltage value is Vref [n] in the period b shown in FIG.
  • the differential amplifier 150 receives an analog voltage whose voltage value output from the D / A converter 120 is Vout [n + 1] and a reference voltage whose voltage value output from the voltage source 140 is Vref [n]. , The difference voltage between the analog voltage and the reference voltage is amplified, and the amplification difference voltage is output to the A / D converter 160.
  • Vamp [n + 1] Vamp [n + 1]
  • Vamp [n + 1] can be expressed by the following equation (2). it can.
  • the amplification factor of the differential amplifier 150 is assumed to be A.
  • Vamp [n + 1] A ⁇ (Vout [n + 1] -Vref [n]) ... Equation (2)
  • the A / D converter 160 receives the amplification difference voltage whose voltage value output by the differential amplifier 150 is Vamp [n + 1], and outputs the second digital code corresponding to Vamp [n + 1] to the voltage difference calculation unit 170. To do.
  • the voltage difference calculation unit 170 receives the second digital code corresponding to Vamp [n + 1] and acquires the value of Vamp [n + 1] by acquiring the voltage value corresponding to the second digital code.
  • the voltage difference calculation unit 170 converts the D / A by dividing the difference between the acquired value of Vamp [n] and the value of Vamp [n + 1] by A, which is the amplification factor of the differential amplifier 150.
  • the voltage difference between the analog voltage having the voltage value corresponding to the first digital code whose code value is n and the analog voltage having the voltage value corresponding to the first digital code whose code value is n + 1 is calculated by the device 120. Obtained as an output voltage difference.
  • the output voltage difference is expressed as ⁇ Vout [n]
  • the output voltage difference can be expressed by the following equation (3).
  • ⁇ Vout [n] (Vamp [n + 1] -Vamp [n]) / A ... Equation (3)
  • the error calculation unit 180 calculates the difference between the value of the voltage [n] and the value of the voltage [n + 1], so that the code output unit 110 outputs the first digital code having the code value n.
  • the ideal voltage value of the analog signal output by the D / A converter 120 and the ideal analog signal output by the D / A converter 120 when the first digital code whose code value is n + 1 is output.
  • the voltage difference from a typical voltage value (hereinafter referred to as "ideal voltage difference") is calculated.
  • ⁇ Videal [n] Videal [n + 1] -Videal [n] ... Equation (4)
  • the error calculation unit 180 calculates the voltage difference between the output voltage difference and the ideal voltage difference, so that the code output unit 110 outputs the first digital code whose code value is n, and the code value.
  • the DNL generated between the time when the first digital code in which is n + 1 is output is calculated.
  • the code output unit 110 outputs the first digital code having the code value n and the first digital code having the code value n + 1, the DNL generated between the output is expressed as DNL [n].
  • Digital [n] can be expressed by the following equation (5).
  • DNL [n] ⁇ Vout [n] ⁇ Videal [n] ... Equation (5)
  • FIG. 3 is a diagram showing an example of a time change of the voltage value of the amplification difference voltage output by the differential amplifier 150 in the error detection circuit 100 according to the first embodiment.
  • the horizontal axis represents time and the vertical axis represents the voltage value of the amplification difference voltage.
  • the solid line shows the time change of the voltage value of the amplification difference voltage output by the differential amplifier 150 in response to the analog voltage including the DNL output by the D / A converter 120.
  • the broken line indicates the voltage of the ideal amplification difference voltage when the D / A converter 120 receives the ideal analog voltage not including the DNL and the differential amplifier 150 outputs the amplification difference voltage. It shows the time change of the value.
  • the numbers shown below the horizontal axis indicate the code values of the first digital code output by the code output unit 110.
  • Vout [n] which indicates the voltage value of the analog voltage actually output by the D / A converter 120, contains DNL as compared with the ideal analog voltage voltage value, which is a differential.
  • the Vamp [n] which is the voltage value of the amplification difference voltage output by the amplifier 150, also includes the DNL. Since the amplification difference voltage is the difference voltage between the analog voltage output by the D / A converter 120 and the reference voltage that is sufficiently amplified by the differential amplifier 150, the DNL included in Vamp [n] is It shows a large value as compared with the DNL contained in Vout [n].
  • the DNL contained in the Vout [n] is smaller than the resolution of the A / D converter 160 and the DNL cannot be detected, it is included in the Vamp [n] showing a value larger than the DNL contained in the Vout [n].
  • the DNL contained in the Vamp [n] is larger than the resolution of the A / D converter 160, the DNL can detect the DNL.
  • the code output unit 110 has detected the DNL [n] that occurs between the time when the first digital code whose code value is n is output and the time when the first digital code whose code value is n + 1 is output.
  • the error detection circuit 100 performs the same operation as the above operation, so that when the code output unit 110 outputs a first digital code having an arbitrary first code, and when the second code adjacent to the first code is output. It is possible to detect the DNL that occurs when the first digital code having the code is output.
  • the error detection circuit 100 receives the code output unit 110 that outputs the first digital code indicating the output voltage value and the first digital code output by the code output unit 110, and corresponds to the first digital code.
  • a D / A converter 120 that outputs an analog voltage
  • a control output unit 130 that outputs a control signal
  • a voltage source that receives a control signal output by the control output unit 130 and outputs a reference voltage corresponding to the control signal.
  • the analog voltage output by the D / A converter 120, and the reference voltage output by the voltage source 140 the difference voltage between the analog voltage and the reference voltage is amplified, and the amplified difference voltage is output.
  • a / D converter 160 that receives the difference voltage after amplification output by the differential amplifier 150 and outputs a second digital code corresponding to the difference voltage after amplification, and A / D conversion. Upon receiving the second digital code output by the device 160, the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value, and the second digital code.
  • D / A converter 120 Based on the second digital code corresponding to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is a value adjacent to the 1 code value, D / The voltage difference calculation unit 170 that calculates the voltage difference between the first analog voltage and the second analog voltage output by the A converter 120 as the output voltage difference, and the output voltage value indicated by the first digital code having the first code value. , An error calculation unit 180 that calculates an error of the output voltage difference calculated by the voltage difference calculation unit 170 based on the voltage difference from the output voltage value indicated by the first digital code having the second code value, and controls.
  • the output unit 130 takes a period until the voltage difference calculation unit 170 receives the second digital code corresponding to the first digital code having the first code value and the second digital code corresponding to the second code value. It is configured to output a control signal that keeps the reference voltage output by the voltage source 140 constant.
  • the error detection circuit 100 is included in the interval between the voltage values of the analog voltage output by the D / A converter 120 even if the A / D converter 160 does not have high resolution.
  • the DNL can be detected with high accuracy. Therefore, for example, when the output terminal 199 of the error detection circuit 100 is connected to the voltage controlled oscillator with the voltage controlled oscillator described in Patent Document 1 as the control target, the error detection circuit 100 is described in Patent Document 1.
  • the measurement accuracy of the radar device can be improved. Further, with this configuration, the error detection circuit 100 can detect the DNL with high accuracy without depending on the accuracy of the reference voltage.
  • the error detection circuit 100 outputs a control signal corresponding to the first digital code output by the code output unit 110, and the voltage source 140 corresponds to the control signal. 1 It is configured to output a reference voltage corresponding to the output voltage value indicated by the digital code.
  • the amplification factor of the differential amplifier 150 can be increased, so that the error detection circuit 100 can perform D / A conversion even if the A / D converter 160 does not have high resolution.
  • the DNL included in the interval between the voltage values of the analog voltage output by the device 120 can be detected with higher accuracy.
  • the error detection circuit 100 includes the voltage source 140 with a second D / A converter, which is different from the D / A converter 120 that outputs an analog voltage corresponding to the first digital code. You may.
  • the control output unit 130 can output a digital code corresponding to the first digital code output by the code output unit 110 as a control signal, so that the control output unit 130 can output the first digital. There is no need to generate a control signal corresponding to the code.
  • the error detection circuit 100 receives the analog voltage output by the D / A converter 120, attenuates the noise signal included in the analog voltage, and reduces the noise signal. It may be provided with a low-pass filter 190 that outputs an analog voltage to the differential amplifier 150. With this configuration, the error detection circuit 100 can output an analog voltage with a reduced noise signal to the control target, and in addition to the DNL included in the analog voltage output by the D / A converter 120, An error in the output voltage due to the low-pass filter 190 can also be detected. When the low-pass filter 190 is provided only for controlling the control target by the analog voltage in which the noise signal is reduced, the low-pass filter 190 is arranged between the output terminal 199 and the control target. However, it may be arranged inside the controlled object.
  • any combination of the embodiments can be freely combined, any component of the embodiment can be modified, or any component can be omitted in each embodiment. ..
  • the error detection circuit according to the present invention can be applied to electronic devices.
  • 100 error detection circuit 110 code output unit, 120 D / A converter, 130 control output unit, 140 voltage source, 150 differential amplifier, 160 A / D converter, 170 voltage difference calculation unit, 180 error calculation unit, 190 Low-pass filter, 199 output terminal.

Abstract

This error detection circuit (100) comprises: a D/A converter (120) for outputting an analog voltage corresponding to a first digital code; a voltage source (140) for outputting a reference voltage corresponding to a control signal; a differential amplifier (150) for amplifying the differential voltage between the analog voltage and reference voltage; an A/D converter (160) for outputting a second digital code corresponding to the amplified differential voltage; a voltage difference calculation unit (170) for calculating, as an output voltage difference, the voltage difference between a first analog voltage and second analog voltage output by the D/A converter (120); and an error calculation unit (180) for calculating the error in the output voltage difference calculated by the voltage difference calculation unit (170). A control output unit (130) outputs a control signal for keeping the reference voltage output by the voltage source (140) fixed during a period until the voltage difference calculation unit (170) receives a second digital code corresponding to a first digital code having a first code value and a second digital code corresponding to a second code value.

Description

誤差検出回路Error detection circuit
　この発明は、誤差検出回路に関するものである。 The present invention relates to an error detection circuit.
　Ｄ／Ａ変換器は、入力されたデジタルコードに対応するアナログ電圧を出力する。Ｄ／Ａ変換器は、例えば、マイコン等の処理回路を備えたデジタル信号を出力する制御装置と、アナログ電圧により制御される制御対象との間に配置される。Ｄ／Ａ変換器は、制御装置と制御対象との間に配置され、制御装置と制御対象とに接続されることにより、制御装置は、Ｄ／Ａ変換器を介して、制御対象を制御することができる。
　Ｄ／Ａ変換器から出力されるアナログ電圧は、デジタルコードに対応した離散的な電圧値を示す。Ｄ／Ａ変換器から出力されるアナログ電圧の離散的な電圧値の間隔は、理想的には一定間隔となる。例えば、Ｄ／Ａ変換器の分解能が、３ビットであれる場合、Ｄ／Ａ変換器は、２の３乗にあたる８段階の電圧値をアナログ電圧として出力することができる。Ｄ／Ａ変換器の分解能が３ビットであり、且つ、Ｄ／Ａ変換器に入力される基準電圧が５ボルト（以下「Ｖ」と表記する。）である場合、Ｄ／Ａ変換器から出力されるアナログ電圧の理想的な電圧値の間隔は、５Ｖを８で除した０．６２５Ｖ間隔となる。 The D / A converter outputs the analog voltage corresponding to the input digital code. The D / A converter is arranged between, for example, a control device provided with a processing circuit such as a microcomputer and outputting a digital signal, and a controlled object controlled by an analog voltage. The D / A converter is arranged between the control device and the control target, and by connecting to the control device and the control target, the control device controls the control target via the D / A converter. be able to.
The analog voltage output from the D / A converter indicates a discrete voltage value corresponding to the digital code. The interval between the discrete voltage values of the analog voltage output from the D / A converter is ideally a constant interval. For example, when the resolution of the D / A converter is 3 bits, the D / A converter can output a voltage value of 8 steps corresponding to 2 to the 3rd power as an analog voltage. When the resolution of the D / A converter is 3 bits and the reference voltage input to the D / A converter is 5 volts (hereinafter referred to as "V"), the output is from the D / A converter. The ideal voltage value interval of the analog voltage to be generated is 0.625V interval obtained by dividing 5V by 8.
　しかしながら、実際は、Ｄ／Ａ変換器から出力されるアナログ電圧の電圧値の間隔は、Ｄ／Ａ変換器を構成する抵抗のばらつき等により誤差を生じる。このような誤差は、微分非直線性誤差（以下「ＤＮＬ（Ｄｉｆｆｅｒｅｎｔｉａｌ　Ｎｏｎ－Ｌｉｎｅａｒｉｔｙ）」という。）と呼ばれている。Ｄ／Ａ変換器から出力されるアナログ電圧は、ＤＮＬにより精度が劣化するため、制御対象を精度よく制御することができない。 However, in reality, the interval between the voltage values of the analog voltage output from the D / A converter causes an error due to variations in the resistors constituting the D / A converter and the like. Such an error is called a differential nonlinearity error (hereinafter referred to as "DNL (Differential Non-Linearity)"). Since the accuracy of the analog voltage output from the D / A converter is deteriorated by DNL, it is not possible to accurately control the control target.
　例えば、特許文献１には、Ｄ／Ａ変換器を適用した電圧制御発振器を制御対象として備えたレーダ装置が開示されている。
　レーダ装置は、出力する信号の周波数を時間に対して線形に変化させた信号を出力する。レーダ装置は、出力する信号における時間に対して変化させた周波数の線形性が高いほど、距離又は相対速度等を高精度で測定できる。しかしながら、Ｄ／Ａ変換器が出力するアナログ電圧にＤＮＬが含まれると、所望の制御電圧に対してＤＮＬの分だけ異なるアナログ電圧が電圧制御発振器に入力される。そのため、レーダ装置が出力する信号における時間に対して変化させた周波数の線形性が劣化し、結果として、レーダ装置が測定する距離又は相対速度等の精度が劣化してしまう。したがって、制御対象を精度よく制御するためには、Ｄ／Ａ変換器が出力するアナログ電圧に含まれるＤＮＬを検出する必要がある。
　特許文献１に記載されたレーダ装置は、Ｄ／Ａ変換器が出力したアナログ電圧の電圧値を、Ａ／Ｄ変換器により構成された電圧計により測定し、測定した電圧値と、所望の電圧値とを比較することによりＤＮＬを検出している。 For example, Patent Document 1 discloses a radar device including a voltage controlled oscillator to which a D / A converter is applied as a control target.
The radar device outputs a signal in which the frequency of the output signal is changed linearly with time. The radar device can measure the distance, the relative speed, etc. with higher accuracy as the linearity of the frequency changed with respect to time in the output signal is higher. However, when the analog voltage output by the D / A converter includes DNL, an analog voltage different from the desired control voltage by the amount of DNL is input to the voltage controlled oscillator. Therefore, the linearity of the frequency changed with respect to time in the signal output by the radar device deteriorates, and as a result, the accuracy of the distance or relative velocity measured by the radar device deteriorates. Therefore, in order to control the controlled object with high accuracy, it is necessary to detect the DNL included in the analog voltage output by the D / A converter.
The radar device described in Patent Document 1 measures the voltage value of the analog voltage output by the D / A converter with a voltmeter configured by the A / D converter, and measures the measured voltage value and a desired voltage. DNL is detected by comparing with the value.
国際公開第２０１８／０２５３４２号International Publication No. 2018/025342
　しかしながら、Ａ／Ｄ変換器は、入力されたアナログ電圧に対応するデジタルコードを出力する。Ａ／Ｄ変換器は連続的なアナログ電圧を離散的なデジタルコードに変換するため、Ａ／Ｄ変換器に入力されるアナログ電圧の電圧値が、Ａ／Ｄ変換器の分解能により決定される所定の電圧値の範囲内である場合、Ａ／Ｄ変換器に入力されるアナログ電圧の電圧値は同一のデジタルコードに変換されてしまう。
　したがって、特許文献１に記載されたレーダ装置のように、Ｄ／Ａ変換器が出力したアナログ電圧を、直接Ａ／Ｄ変換器に入力する場合、Ｄ／Ａ変換器が出力したアナログ電圧のＤＮＬを精度良く検出するためには、Ａ／Ｄ変換器は、Ｄ／Ａ変換器の分解能より高い分解能を有するＡ／Ｄ変換器であることが求められる。しかしながら、Ａ／Ｄ変換器の分解能には限界があるため、検出したいＤＮＬの精度を満足する分解能をＡ／Ｄ変換器が有さない場合、ＤＮＬを所望の検出精度で得ることができない。 However, the A / D converter outputs a digital code corresponding to the input analog voltage. Since the A / D converter converts a continuous analog voltage into a discrete digital code, the voltage value of the analog voltage input to the A / D converter is determined by the resolution of the A / D converter. If it is within the range of the voltage value of, the voltage value of the analog voltage input to the A / D converter is converted into the same digital code.
Therefore, when the analog voltage output by the D / A converter is directly input to the A / D converter as in the radar device described in Patent Document 1, the DNL of the analog voltage output by the D / A converter is used. The A / D converter is required to be an A / D converter having a resolution higher than that of the D / A converter in order to accurately detect the above. However, since the resolution of the A / D converter is limited, if the A / D converter does not have a resolution that satisfies the accuracy of the DNL to be detected, the DNL cannot be obtained with a desired detection accuracy.
　この発明は、上述の問題点を解決するためのもので、高い分解能を有していないＡ／Ｄ変換器であっても、Ｄ／Ａ変換器が出力するアナログ電圧の電圧値の間隔に含まれるＤＮＬを高い精度で検出できる誤差検出回路を提供することを目的としている。 The present invention is for solving the above-mentioned problems, and even if the A / D converter does not have high resolution, it is included in the interval between the voltage values of the analog voltage output by the D / A converter. It is an object of the present invention to provide an error detection circuit capable of detecting a DNL with high accuracy.
　この発明に係る誤差検出回路は、出力電圧値を示す第１デジタルコードを出力するコード出力部と、コード出力部が出力した第１デジタルコードを受けて、第１デジタルコードに対応するアナログ電圧を出力するＤ／Ａ変換器と、制御信号を出力する制御出力部と、制御出力部が出力した制御信号を受けて、制御信号に対応する基準電圧を出力する電圧源と、Ｄ／Ａ変換器が出力したアナログ電圧と、電圧源が出力した基準電圧とを受けて、アナログ電圧と基準電圧との差電圧を増幅して、増幅後の差電圧を出力する差動増幅器と、差動増幅器が出力した増幅後の差電圧を受けて、増幅後の差電圧に対応する第２デジタルコードを出力するＡ／Ｄ変換器と、Ａ／Ｄ変換器が出力した第２デジタルコードを受けて、第１コード値を有する第１デジタルコードに対応してＤ／Ａ変換器が出力した第１アナログ電圧に対応する第２デジタルコードと、第１コード値に隣接する値である第２コード値を有する第１デジタルコードに対応してＤ／Ａ変換器が出力した第２アナログ電圧に対応する第２デジタルコードとに基づいて、Ｄ／Ａ変換器が出力した第１アナログ電圧と第２アナログ電圧との電圧差を出力電圧差として算出する電圧差算出部と、第１コード値を有する第１デジタルコードが示す出力電圧値と、第２コード値を有する第１デジタルコードが示す出力電圧値との電圧差に基づいて、電圧差算出部が算出した出力電圧差の誤差を算出する誤差算出部と、を備え、制御出力部は、電圧差算出部が、第１コード値を有する第１デジタルコードに対応する第２デジタルコードと、第２コード値に対応する第２デジタルコードとを受けるまでの期間において、電圧源が出力する基準電圧を一定に保つ制御信号を出力するように構成した。 The error detection circuit according to the present invention receives a code output unit that outputs a first digital code indicating an output voltage value and a first digital code output by the code output unit, and outputs an analog voltage corresponding to the first digital code. An output D / A converter, a control output unit that outputs a control signal, a voltage source that receives the control signal output by the control output unit and outputs a reference voltage corresponding to the control signal, and a D / A converter. A differential amplifier that receives the analog voltage output by and the reference voltage output by the voltage source, amplifies the difference voltage between the analog voltage and the reference voltage, and outputs the amplified difference voltage. Upon receiving the output differential voltage after amplification, the A / D converter that outputs the second digital code corresponding to the differential voltage after amplification and the second digital code output by the A / D converter are received and the second digital code is received. It has a second digital code corresponding to the first analog voltage output by the D / A converter corresponding to the first digital code having one code value, and a second code value which is a value adjacent to the first code value. The first analog voltage and the second analog voltage output by the D / A converter are based on the second digital code corresponding to the second analog voltage output by the D / A converter corresponding to the first digital code. The voltage difference calculation unit that calculates the voltage difference of the above as the output voltage difference, the output voltage value indicated by the first digital code having the first code value, and the output voltage value indicated by the first digital code having the second code value. The control output unit includes a first digital code in which the voltage difference calculation unit has a first code value, and includes an error calculation unit that calculates an error of the output voltage difference calculated by the voltage difference calculation unit based on the voltage difference. It is configured to output a control signal that keeps the reference voltage output by the voltage source constant in the period until the second digital code corresponding to the above and the second digital code corresponding to the second code value are received.
　この発明によれば、高い分解能を有していないＡ／Ｄ変換器であっても、Ｄ／Ａ変換器が出力するアナログ電圧の電圧値の間隔に含まれるＤＮＬを高い精度で検出できる。 According to the present invention, even an A / D converter that does not have a high resolution can detect DNL included in the interval of the voltage value of the analog voltage output by the D / A converter with high accuracy.
図１は、実施の形態１に係る誤差検出回路の要部の構成の一例を示すブロック図である。FIG. 1 is a block diagram showing an example of the configuration of a main part of the error detection circuit according to the first embodiment. 図２は、実施の形態１に係る誤差検出回路におけるＤ／Ａ変換器が出力するアナログ電圧の電圧値、及び、電圧源が出力する基準電圧の電圧値の時間変化を示す図である。FIG. 2 is a diagram showing a time change of a voltage value of an analog voltage output by a D / A converter in the error detection circuit according to the first embodiment and a voltage value of a reference voltage output by a voltage source. 図３は、実施の形態１に係る誤差検出回路における差動増幅器が出力する増幅差電圧の電圧値の時間変化の一例を示す図である。FIG. 3 is a diagram showing an example of a time change of the voltage value of the amplification difference voltage output by the differential amplifier in the error detection circuit according to the first embodiment.
　以下、この発明の実施の形態について、図面を参照しながら詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
実施の形態１．
　図１から図３を参照して実施の形態１に係る誤差検出回路１００について説明する。 Embodiment 1.
The error detection circuit 100 according to the first embodiment will be described with reference to FIGS. 1 to 3.
　図１を参照して、実施の形態１に係る誤差検出回路１００の要部の構成について説明する。
　図１は、実施の形態１に係る誤差検出回路１００の要部の構成の一例を示すブロック図である。
　誤差検出回路１００は、コード出力部１１０、Ｄ／Ａ変換器１２０、制御出力部１３０、電圧源１４０、差動増幅器１５０、Ａ／Ｄ変換器１６０、電圧差算出部１７０、誤差算出部１８０、及び出力端子１９９を備える。誤差検出回路１００は、上述の構成に加えて、ローパスフィルタ１９０を備えるものであっても良い。図１は、誤差検出回路１００が、コード出力部１１０、Ｄ／Ａ変換器１２０、制御出力部１３０、電圧源１４０、差動増幅器１５０、Ａ／Ｄ変換器１６０、電圧差算出部１７０、誤差算出部１８０、及び出力端子１９９、並びに、ローパスフィルタ１９０を備えたものを示している。 The configuration of the main part of the error detection circuit 100 according to the first embodiment will be described with reference to FIG.
FIG. 1 is a block diagram showing an example of the configuration of a main part of the error detection circuit 100 according to the first embodiment.
The error detection circuit 100 includes a code output unit 110, a D / A converter 120, a control output unit 130, a voltage source 140, a differential amplifier 150, an A / D converter 160, a voltage difference calculation unit 170, and an error calculation unit 180. And an output terminal 199. The error detection circuit 100 may include a low-pass filter 190 in addition to the above configuration. In FIG. 1, the error detection circuit 100 includes a code output unit 110, a D / A converter 120, a control output unit 130, a voltage source 140, a differential amplifier 150, an A / D converter 160, a voltage difference calculation unit 170, and an error. The one provided with the calculation unit 180, the output terminal 199, and the low-pass filter 190 is shown.
　コード出力部１１０は、出力電圧値を示す第１デジタルコードを出力する。
　Ｄ／Ａ変換器１２０は、コード出力部１１０が出力した第１デジタルコードを受けて、第１デジタルコードに対応するアナログ電圧を出力する。具体的には、Ｄ／Ａ変換器１２０は、複数の離散的な電圧値のうち、第１デジタルコードに対応する電圧値を有するアナログ電圧を出力する。図１に示すように、誤差検出回路１００がローパスフィルタ１９０を備える場合、Ｄ／Ａ変換器１２０は、アナログ電圧を、ローパスフィルタ１９０を介して、出力端子１９９及び差動増幅器１５０に出力する。
　出力端子１９９は、制御対象（不図示）と、Ｄ／Ａ変換器１２０とを接続するための端子である。制御対象は、Ｄ／Ａ変換器１２０が出力したアナログ電圧を受けて、当該アナログ電圧により制御される。
　ローパスフィルタ１９０は、Ｄ／Ａ変換器１２０が出力したアナログ電圧を受けて、当該アナログ電圧のうち、予め定められた遮断周波数より高い周波数成分のアナログ電圧を減衰させ、当該遮断周波数より低い周波数成分のアナログ電圧を通過させる。 The code output unit 110 outputs a first digital code indicating an output voltage value.
The D / A converter 120 receives the first digital code output by the code output unit 110 and outputs an analog voltage corresponding to the first digital code. Specifically, the D / A converter 120 outputs an analog voltage having a voltage value corresponding to the first digital code among a plurality of discrete voltage values. As shown in FIG. 1, when the error detection circuit 100 includes a low-pass filter 190, the D / A converter 120 outputs an analog voltage to the output terminal 199 and the differential amplifier 150 via the low-pass filter 190.
The output terminal 199 is a terminal for connecting a control target (not shown) and the D / A converter 120. The control target receives the analog voltage output by the D / A converter 120 and is controlled by the analog voltage.
The low-pass filter 190 receives the analog voltage output by the D / A converter 120 and attenuates the analog voltage of the frequency component higher than the predetermined cutoff frequency among the analog voltage, and the frequency component lower than the cutoff frequency. Pass the analog voltage of.
　制御出力部１３０は、制御信号を電圧源１４０に出力する。具体的には、例えば、制御出力部１３０は、コード出力部１１０が出力した第１デジタルコードに対応する制御信号を電圧源１４０に出力する。
　電圧源１４０は、制御出力部１３０が出力した制御信号を受けて、制御信号に対応する基準電圧を差動増幅器１５０に出力する。具体的には、例えば、電圧源１４０は、制御信号に対応する第１デジタルコードが示す出力電圧値に相当する基準電圧を差動増幅器１５０に出力する。ここで、第１デジタルコードが示す出力電圧値に相当する値は、例えば、第１デジタルコードが示す出力電圧値に略等しい電圧値であり、第１デジタルコードが示す理想的な電圧値に略等しい電圧値である。電圧源１４０は、例えば、上述の第１デジタルコードに対応するアナログ電圧を出力するＤ／Ａ変換器１２０とは異なる、第２のＤ／Ａ変換器により構成される。実施の形態１では、電圧源１４０は、第２のＤ／Ａ変換器により構成されるものとして説明するが、電圧源１４０は、汎用の直流電源により構成されたものであっても良い。 The control output unit 130 outputs a control signal to the voltage source 140. Specifically, for example, the control output unit 130 outputs a control signal corresponding to the first digital code output by the code output unit 110 to the voltage source 140.
The voltage source 140 receives the control signal output by the control output unit 130 and outputs a reference voltage corresponding to the control signal to the differential amplifier 150. Specifically, for example, the voltage source 140 outputs a reference voltage corresponding to the output voltage value indicated by the first digital code corresponding to the control signal to the differential amplifier 150. Here, the value corresponding to the output voltage value indicated by the first digital code is, for example, a voltage value substantially equal to the output voltage value indicated by the first digital code, and is substantially equal to the ideal voltage value indicated by the first digital code. Equal voltage values. The voltage source 140 is composed of, for example, a second D / A converter different from the D / A converter 120 that outputs an analog voltage corresponding to the first digital code described above. In the first embodiment, the voltage source 140 will be described as being configured by the second D / A converter, but the voltage source 140 may be configured by a general-purpose DC power supply.
　差動増幅器１５０は、２つの入力端子を有し、一方の入力端子には、Ｄ／Ａ変換器１２０が出力したアナログ電圧が入力され、他方の入力端子には、電圧源１４０が出力した基準電圧が入力される。差動増幅器１５０は、Ｄ／Ａ変換器１２０が出力したアナログ電圧と、電圧源１４０が出力した基準電圧とを受けて、アナログ電圧と基準電圧との差電圧を増幅して、増幅後の差電圧をＡ／Ｄ変換器１６０に出力する。
　Ａ／Ｄ変換器１６０は、差動増幅器１５０が出力した増幅後の差電圧を受けて、増幅後の差電圧に対応する第２デジタルコードを電圧差算出部１７０に出力する。実施の形態１に係る誤差検出回路１００は、Ａ／Ｄ変換器１６０を備えるものとして説明するが、誤差検出回路１００は、Ａ／Ｄ変換器１６０に換えて汎用の電圧計（不図示）を備えたものであっても良い。 The differential amplifier 150 has two input terminals, one input terminal is input with an analog voltage output by the D / A converter 120, and the other input terminal is a reference voltage output by the voltage source 140. The voltage is input. The differential amplifier 150 receives the analog voltage output by the D / A converter 120 and the reference voltage output by the voltage source 140, amplifies the difference voltage between the analog voltage and the reference voltage, and the difference after amplification. The voltage is output to the A / D converter 160.
The A / D converter 160 receives the amplified difference voltage output by the differential amplifier 150 and outputs a second digital code corresponding to the amplified difference voltage to the voltage difference calculation unit 170. The error detection circuit 100 according to the first embodiment will be described as including the A / D converter 160, but the error detection circuit 100 uses a general-purpose voltmeter (not shown) in place of the A / D converter 160. It may be provided.
　電圧差算出部１７０は、Ａ／Ｄ変換器１６０が出力した第２デジタルコードを受ける。
　より具体的には、電圧差算出部１７０は、第１コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第１アナログ電圧に対応する第２デジタルコードを受ける。また、電圧差算出部１７０は、第１コード値に隣接する値である第２コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第２アナログ電圧に対応する第２デジタルコードを受ける。 The voltage difference calculation unit 170 receives the second digital code output by the A / D converter 160.
More specifically, the voltage difference calculation unit 170 receives the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value. Further, the voltage difference calculation unit 170 corresponds to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is a value adjacent to the first code value. 2 Receive a digital code.
　ここで、第１コード値に隣接する値とは、Ｄ／Ａ変換器１２０が第１デジタルコードに対応して出力するアナログ電圧の離散的な電圧値のうち、Ｄ／Ａ変換器１２０が第１コード値を有する第１デジタルコードに対応して出力するアナログ電圧の電圧値に隣接する電圧値のアナログ電圧を、Ｄ／Ａ変換器１２０が出力するための第１デジタルコードの値である。より具体的には、例えば、Ｄ／Ａ変換器１２０が、第１デジタルコードに対応して０．６２５Ｖ間隔の離散的な電圧値を有するアナログ電圧を出力するものであって、Ｄ／Ａ変換器１２０が、第１コード値を有する第１デジタルコードを受けた際に電圧値が２．５Ｖであるアナログ信号を出力する場合、Ｄ／Ａ変換器１２０は、第１コード値に隣接する値である第２コード値を有する第１デジタルコードを受けた際に電圧値が３．１２５Ｖ（＝２．５Ｖ＋０．６２５Ｖ）又は１．８７５Ｖ（＝２．５－０．６２５Ｖ）であるアナログ信号を出力する。 Here, the value adjacent to the first code value is the discrete voltage value of the analog voltage output by the D / A converter 120 corresponding to the first digital code, and the D / A converter 120 is the first. It is the value of the first digital code for the D / A converter 120 to output the analog voltage of the voltage value adjacent to the voltage value of the analog voltage output corresponding to the first digital code having one code value. More specifically, for example, the D / A converter 120 outputs an analog voltage having discrete voltage values at intervals of 0.625 V corresponding to the first digital code, and D / A conversion. When the device 120 outputs an analog signal having a voltage value of 2.5V when receiving the first digital code having the first code value, the D / A converter 120 has a value adjacent to the first code value. An analog signal having a voltage value of 3.125V (= 2.5V + 0.625V) or 1.875V (= 2.5-0.625V) when receiving a first digital code having a second code value of Output.
　電圧差算出部１７０は、第１コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第１アナログ電圧に対応する第２デジタルコードと、第１コード値に隣接する値である第２コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第２アナログ電圧に対応する第２デジタルコードとに基づいて、Ｄ／Ａ変換器１２０が出力した第１アナログ電圧と第２アナログ電圧との電圧差を出力電圧差として算出する。
　より具体的には、電圧差算出部１７０は、第１コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第１アナログ電圧に対応する第２デジタルコードに基づいて、当該第２デジタルコードが示す電圧値を取得する。また、第１コード値に隣接する値である第２コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第２アナログ電圧に対応する第２デジタルコードに基づいて、当該第２デジタルコードが示す電圧値を取得する。電圧差算出部１７０は、取得した上述の２つの電圧値の差を算出することにより、Ｄ／Ａ変換器１２０が出力した第１アナログ電圧と第２アナログ電圧との電圧差を出力電圧差として算出する。 The voltage difference calculation unit 170 is adjacent to the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value and the first code value. The D / A converter 120 outputs based on the second digital code corresponding to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is the value. The voltage difference between the first analog voltage and the second analog voltage is calculated as the output voltage difference.
More specifically, the voltage difference calculation unit 170 is based on the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value. , Acquires the voltage value indicated by the second digital code. Further, based on the second digital code corresponding to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is a value adjacent to the first code value. The voltage value indicated by the second digital code is acquired. The voltage difference calculation unit 170 calculates the difference between the two acquired voltage values, and uses the voltage difference between the first analog voltage and the second analog voltage output by the D / A converter 120 as the output voltage difference. calculate.
　誤差算出部１８０は、第１コード値を有する第１デジタルコードが示す出力電圧値と、第２コード値を有する第１デジタルコードが示す出力電圧値との電圧差に基づいて、電圧差算出部１７０が算出した出力電圧差の誤差を算出する。 The error calculation unit 180 is a voltage difference calculation unit based on the voltage difference between the output voltage value indicated by the first digital code having the first code value and the output voltage value indicated by the first digital code having the second code value. The error of the output voltage difference calculated by 170 is calculated.
　具体的には、例えば、誤差算出部１８０は、コード出力部１１０から第１デジタルコードを取得し、取得した第１デジタルコードに基づいて、第１デジタルコードが示す出力電圧値を取得する。より具体的には、誤差算出部１８０は、取得した第１コード値を有する第１デジタルコードに基づいて、第１コード値を有する第１デジタルコードが示す出力電圧値を取得する。また、誤差算出部１８０は、取得した第２コード値を有する第１デジタルコードに基づいて、第２コード値を有する第１デジタルコードが示す出力電圧値を取得する。誤差算出部１８０は、取得した上述の２つの電圧値の差を算出することにより、第１コード値を有する第１デジタルコードが示す出力電圧値と、第２コード値を有する第１デジタルコードが示す出力電圧値との電圧差を算出する。誤差算出部１８０は、算出した第１コード値を有する第１デジタルコードが示す出力電圧値と、第２コード値を有する第１デジタルコードが示す出力電圧値との電圧差と、電圧差算出部１７０が算出した出力電圧差とを比較することにより、電圧差算出部１７０が算出した出力電圧差の誤差を算出する。 Specifically, for example, the error calculation unit 180 acquires the first digital code from the code output unit 110, and acquires the output voltage value indicated by the first digital code based on the acquired first digital code. More specifically, the error calculation unit 180 acquires the output voltage value indicated by the first digital code having the first code value based on the acquired first digital code having the first code value. Further, the error calculation unit 180 acquires the output voltage value indicated by the first digital code having the second code value based on the acquired first digital code having the second code value. The error calculation unit 180 calculates the difference between the two acquired voltage values so that the output voltage value indicated by the first digital code having the first code value and the first digital code having the second code value can be obtained. Calculate the voltage difference from the indicated output voltage value. The error calculation unit 180 is a voltage difference calculation unit and a voltage difference between the output voltage value indicated by the first digital code having the calculated first code value and the output voltage value indicated by the first digital code having the second code value. By comparing with the output voltage difference calculated by 170, the error of the output voltage difference calculated by the voltage difference calculation unit 170 is calculated.
　制御出力部１３０は、電圧差算出部１７０が、第１コード値を有する第１デジタルコードに対応する第２デジタルコードと、第２コード値に対応する第２デジタルコードとを受けるまでの期間において、電圧源１４０が出力する基準電圧を一定に保つ制御信号を出力する。 The control output unit 130 is in the period until the voltage difference calculation unit 170 receives the second digital code corresponding to the first digital code having the first code value and the second digital code corresponding to the second code value. , Outputs a control signal that keeps the reference voltage output by the voltage source 140 constant.
　なお、コード出力部１１０、制御出力部１３０、電圧差算出部１７０、及び誤差算出部１８０は、マイクロコンピュータ等のコンピュータ（不図示）により構成される。コンピュータは、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、ＧＰＵ（Ｇｒａｐｈｉｃｓ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、マイクロプロセッサ、マイクロコントローラ、又はＤＳＰ（Ｄｉｇｉｔａｌ　Ｓｉｇｎａｌ　Ｐｒｏｃｅｓｓｏｒ）等により構成されたプロセッサ（不図示）と、ＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）、ＲＯＭ（Ｒｅａｄ―Ｏｎｌｙ　Ｍｅｍｏｒｙ）、フラッシュメモリ、ＥＰＲＯＭ（Ｅｒａｓａｂｌｅ　Ｐｒｏｇｒａｍｍａｂｌｅ　Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）、ＥＥＰＲＯＭ（Ｅｌｅｃｔｒｉｃａｌｌｙ　Ｅｒａｓａｂｌｅ　Ｐｒｏｇｒａｍｍａｂｌｅ　Ｒｅａｄ－Ｏｎｌｙ　Ｍｅｍｏｒｙ）、若しくは、ＳＳＤ（Ｓｏｌｉｄ　Ｓｔａｔｅ　Ｄｒｉｖｅ）等の半導体メモリ、又は、ＨＤＤ（Ｈａｒｄ　Ｄｉｓｋ　Ｄｒｉｖｅ）等の半導体メモリ等の磁気ディスク等により構成されたメモリ（不図示）とを有する。 The code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 are composed of a computer (not shown) such as a microcomputer. The computer includes a processor (not shown) composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a microprocessor, a microcontroller, or a DSP (Digital Signal Processor), a RAM (Radom Access Memory), and a ROM. (Read-Only Memory), flash memory, EEPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Erasableprogrammable Read-Only Memory, Memory Hide ), Etc. It has a memory (not shown) composed of a magnetic disk or the like such as a semiconductor memory.
　メモリには、当該コンピュータをコード出力部１１０、制御出力部１３０、電圧差算出部１７０、及び誤差算出部１８０として機能させるためのプログラムが記憶されている。メモリに記憶されているプログラムをプロセッサが読み出して実行することにより、コード出力部１１０、制御出力部１３０、電圧差算出部１７０、及び誤差算出部１８０の機能が実現される。 A program for making the computer function as a code output unit 110, a control output unit 130, a voltage difference calculation unit 170, and an error calculation unit 180 is stored in the memory. When the processor reads and executes the program stored in the memory, the functions of the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 are realized.
　また、コード出力部１１０、制御出力部１３０、電圧差算出部１７０、及び誤差算出部１８０は、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）、ＰＬＤ（Ｐｒｏｇｒａｍｍａｂｌｅ　Ｌｏｇｉｃ　Ｄｅｖｉｃｅ）、ＦＰＧＡ（Ｆｉｅｌｄ－Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）、ＳｏＣ（Ｓｙｓｔｅｍ－ｏｎ－ａ－Ｃｈｉｐ）、又はシステムＬＳＩ（Ｌａｒｇｅ－Ｓｃａｌｅ Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）等の処理回路（不図示）により構成されても良い。
　また、コード出力部１１０、制御出力部１３０、電圧差算出部１７０、及び誤差算出部１８０は、コード出力部１１０、制御出力部１３０、電圧差算出部１７０、及び誤差算出部１８０の機能のうちの一部の機能がプロセッサ及びメモリにより実現され、残余の機能が処理回路により実現されるものであっても良い。 Further, the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 include an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), an FPGA (Field-Programmable), and an FPGA (Field-Programmable). It may be configured by a processing circuit (not shown) such as (System-on-a-Chip) or a system LSI (Lage-Scale Integrated Circuit).
Further, the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180 are among the functions of the code output unit 110, the control output unit 130, the voltage difference calculation unit 170, and the error calculation unit 180. A part of the functions may be realized by the processor and the memory, and the remaining functions may be realized by the processing circuit.
　図２及び図３を参照して、実施の形態１に係る誤差検出回路１００動作について説明する。
　図２は、実施の形態１に係る誤差検出回路１００におけるＤ／Ａ変換器１２０が出力するアナログ電圧の電圧値、及び、電圧源１４０が出力する基準電圧の電圧値の時間変化を示す図である。
　図２において、横軸は時間を示し、縦軸は電圧値を示している。
　また、図２において、細い実線は、Ｄ／Ａ変換器１２０が出力するアナログ電圧の電圧値の時間変化を示し、太い実線は、電圧源１４０が出力する基準電圧の電圧値の時間変化を示している。なお、図２において、破線は、Ｄ／Ａ変換器１２０が出力するアナログ電圧がＤＮＬを含まない理想的なアナログ電圧を出力する場合の当該アナログ電圧の電圧値の時間変化である。 The operation of the error detection circuit 100 according to the first embodiment will be described with reference to FIGS. 2 and 3.
FIG. 2 is a diagram showing a time change of the voltage value of the analog voltage output by the D / A converter 120 in the error detection circuit 100 according to the first embodiment and the voltage value of the reference voltage output by the voltage source 140. is there.
In FIG. 2, the horizontal axis represents time and the vertical axis represents voltage value.
Further, in FIG. 2, the thin solid line shows the time change of the voltage value of the analog voltage output by the D / A converter 120, and the thick solid line shows the time change of the voltage value of the reference voltage output by the voltage source 140. ing. In FIG. 2, the broken line is the time change of the voltage value of the analog voltage when the analog voltage output by the D / A converter 120 outputs an ideal analog voltage that does not include DNL.
　また、図２において、横軸の下に示す数字は、コード出力部１１０が出力する第１デジタルコードのコード値を示している。図２は、一例として、コード出力部１１０から出力される第１デジタルコードが、Ｎ（Ｎは１以上の自然数）ビットにより構成される任意のコード値を有する場合を示している。すなわち、図２は、コード出力部１１０から出力される第１デジタルコードが、コード値として、０から２Ｎ－１までの任意の値を有する場合を示すものである。
　コード出力部１１０は、コード値が０から２Ｎ－１までの第１デジタルコードを順次出力する。以下、図２に示すように、コード出力部１１０は、第１デジタルコードのコード値が０，１，２，・・・，２Ｎ－２，２Ｎ－１の順になるように、第１デジタルコードを出力するものとして説明する。なお、コード出力部１１０が出力する第１デジタルコードのコード値の順序は、０，１，２，・・・，２Ｎ－２，２Ｎ－１に限らず、例えば、２Ｎ－１，２Ｎ－２，・・・，２，１，０の順であっても良い。 Further, in FIG. 2, the numbers shown below the horizontal axis indicate the code values of the first digital code output by the code output unit 110. FIG. 2 shows, as an example, a case where the first digital code output from the code output unit 110 has an arbitrary code value composed of N (N is a natural number of 1 or more) bits. That is, FIG. 2 shows a case where the first digital code output from the code output unit 110 has an arbitrary value from 0 to 2 N -1 as a code value.
The code output unit 110 sequentially outputs the first digital code having a code value from 0 to 2 N -1. Hereinafter, as shown in FIG. 2, the code output unit 110 is first so that the code values of the first digital code are in the order of 0, 1, 2, ..., 2 N- 2,2 N -1. It will be described as outputting a digital code. The order of the first code value of the digital code encoding output unit 110 outputs 0, 1, 2, ... is not limited to 2 N -2, 2 N -1, for example, 2 N -1, The order may be 2N- 2, ..., 2,1,0.
　コード出力部１１０から第１デジタルコードが出力されると、第１デジタルコードを受けたＤ／Ａ変換器１２０は、当該第１デジタルコードに対応する電圧値のアナログ電圧を出力する。
　Ｄ／Ａ変換器１２０が出力するアナログ電圧に含まれるＤＮＬは、Ｄ／Ａ変換器１２０が第１コード値を有する第１デジタルコードを受けた際にＤ／Ａ変換器１２０が出力するアナログ電圧の電圧値と、Ｄ／Ａ変換器１２０が第１コード値に隣接する第２コード値を有する第１デジタルコードを受けた際にＤ／Ａ変換器１２０が出力するアナログ電圧の電圧値とを用いて求める。
　以下、第１コード値がｎ（ｎは０以上２Ｎ－２以下の自然数）であり、第２コード値がｎ＋１である場合について説明する。 When the first digital code is output from the code output unit 110, the D / A converter 120 that has received the first digital code outputs an analog voltage having a voltage value corresponding to the first digital code.
The DNL included in the analog voltage output by the D / A converter 120 is the analog voltage output by the D / A converter 120 when the D / A converter 120 receives the first digital code having the first code value. And the voltage value of the analog voltage output by the D / A converter 120 when the D / A converter 120 receives the first digital code having the second code value adjacent to the first code value. Obtained by using.
Hereinafter, a case where the first code value is n (n is a natural number of 0 or more and 2 N -2 or less) and the second code value is n + 1 will be described.
　まず、コード出力部１１０は、図２に示す期間ａにおいて、コード値がｎである第１デジタルコードをＤ／Ａ変換器１２０に出力する。具体的には、例えば、コード出力部１１０は、図２に示す期間ａの始期において、コード値がｎである第１デジタルコードを出力する。コード出力部１１０が、コード値がｎである第１デジタルコードを出力する時点は、期間ａの始期より前であっても良い。
　Ｄ／Ａ変換器１２０は、コード値がｎである第１デジタルコードを受けて、当該第１デジタルコードに対応する電圧値のアナログ電圧、すなわち、上述の第１アナログ電圧を差動増幅器１５０に出力する。Ｄ／Ａ変換器１２０から出力される第１アナログ電圧は、所望の電圧値、すなわち、理想的な電圧値に対して誤差を含んでいる。
　以下、Ｄ／Ａ変換器１２０が、コード値がｎである第１デジタルコードを受けた際に出力するアナログ電圧の電圧値をＶｏｕｔ［ｎ］と表記し、理想的な電圧値である所望の電圧値をＶｉｄｅａｌ［ｎ］と表記する。 First, the code output unit 110 outputs the first digital code having the code value n to the D / A converter 120 during the period a shown in FIG. Specifically, for example, the code output unit 110 outputs a first digital code having a code value of n at the beginning of the period a shown in FIG. The time point at which the code output unit 110 outputs the first digital code whose code value is n may be before the start of the period a.
The D / A converter 120 receives the first digital code having a code value of n, and transfers the analog voltage of the voltage value corresponding to the first digital code, that is, the above-mentioned first analog voltage to the differential amplifier 150. Output. The first analog voltage output from the D / A converter 120 contains an error with respect to a desired voltage value, that is, an ideal voltage value.
Hereinafter, the voltage value of the analog voltage output when the D / A converter 120 receives the first digital code having the code value n is expressed as Vout [n], and is a desired voltage value which is an ideal voltage value. The voltage value is expressed as Digital [n].
　一方、制御出力部１３０は、図２に示す期間ａにおいて、制御信号を電圧源１４０に出力する。具体的には、例えば、コード出力部１１０は、図２に示す期間ａの始期において、制御信号を出力する。コード出力部１１０が制御信号を出力する時点は、期間ａの始期より前であっても良い。
　電圧源１４０は、制御出力部１３０が出力した制御信号を受けて、図２に示す期間ａにおいて、当該制御信号に対応する電圧値の基準電圧を差動増幅器１５０に出力する。
　制御出力部１３０が出力する制御信号は、Ｄ／Ａ変換器１２０から出力されるアナログ電圧の電圧値に近い電圧値の基準電圧が電圧源１４０から出力されるように選択されることが望ましい。例えば、制御出力部１３０は、コード出力部１１０が出力する第１デジタルコードを受けて、当該第１デジタルコードに対応する電圧値の基準電圧を出力することにより、基準電圧の電圧値をＤ／Ａ変換器１２０から出力されるアナログ電圧の電圧値に近い電圧値にすることができる。以下、電圧源１４０が、コード値がｎである第１デジタルコードを受けた際に出力する基準電圧の電圧値をＶｒｅｆ［ｎ］と表記する。 On the other hand, the control output unit 130 outputs a control signal to the voltage source 140 during the period a shown in FIG. Specifically, for example, the code output unit 110 outputs a control signal at the beginning of the period a shown in FIG. The time point at which the code output unit 110 outputs the control signal may be before the start of the period a.
The voltage source 140 receives the control signal output by the control output unit 130, and outputs the reference voltage of the voltage value corresponding to the control signal to the differential amplifier 150 in the period a shown in FIG.
It is desirable that the control signal output by the control output unit 130 is selected so that the reference voltage having a voltage value close to the voltage value of the analog voltage output from the D / A converter 120 is output from the voltage source 140. For example, the control output unit 130 receives the first digital code output by the code output unit 110 and outputs the reference voltage of the voltage value corresponding to the first digital code to D / D the voltage value of the reference voltage. The voltage value can be set to be close to the voltage value of the analog voltage output from the A converter 120. Hereinafter, the voltage value of the reference voltage output when the voltage source 140 receives the first digital code whose code value is n is referred to as Vref [n].
　差動増幅器１５０は、Ｄ／Ａ変換器１２０から出力される電圧値がＶｏｕｔ［ｎ］であるアナログ電圧と、電圧源１４０から出力される電圧値がＶｒｅｆ［ｎ］の基準電圧とを受けて、当該アナログ電圧と当該基準電圧との差電圧を増幅し、増幅後の差電圧（以下「増幅差電圧」という。）をＡ／Ｄ変換器１６０に出力する。差動増幅器１５０の増幅率をＡと表記し、コード値がｎである第１デジタルコードに対応する差動増幅器１５０が出力する増幅差電圧の電圧値をＶａｍｐ［ｎ］と表記すると、Ｖａｍｐ［ｎ］は、次式（１）で表すことができる。
　Ｖａｍｐ［ｎ］＝Ａ×（Ｖｏｕｔ［ｎ］－Ｖｒｅｆ［ｎ］）・・・式（１） The differential amplifier 150 receives an analog voltage whose voltage value output from the D / A converter 120 is Vout [n] and a reference voltage whose voltage value output from the voltage source 140 is Vref [n]. , The difference voltage between the analog voltage and the reference voltage is amplified, and the amplified difference voltage (hereinafter referred to as “amplification difference voltage”) is output to the A / D converter 160. When the amplification factor of the differential amplifier 150 is expressed as A and the voltage value of the amplification difference voltage output by the differential amplifier 150 corresponding to the first digital code whose code value is n is expressed as Vamp [n], Vamp [ n] can be expressed by the following equation (1).
Vamp [n] = A × (Vout [n] -Vref [n]) ... Equation (1)
　Ａ／Ｄ変換器１６０は、差動増幅器１５０が出力した電圧値がＶａｍｐ［ｎ］である増幅差電圧を受けて、電圧値がＶａｍｐ［ｎ］である増幅差電圧に対応する第２デジタルコードを電圧差算出部１７０に出力する。
　電圧差算出部１７０は、Ｖａｍｐ［ｎ］に対応する第２デジタルコードを受けて、当該第２デジタルコードに対応する電圧値を取得することにより、Ｖａｍｐ［ｎ］の値を取得する。 The A / D converter 160 receives the amplification difference voltage whose voltage value output by the differential amplifier 150 is Vamp [n], and the second digital code corresponding to the amplification difference voltage whose voltage value is Vamp [n]. Is output to the voltage difference calculation unit 170.
The voltage difference calculation unit 170 receives the second digital code corresponding to Vamp [n] and acquires the value of Vamp [n] by acquiring the voltage value corresponding to the second digital code.
　次に、コード出力部１１０は、図２に示す期間ｂにおいて、コード値がｎ＋１である第１デジタルコードをＤ／Ａ変換器１２０に出力する。具体的には、例えば、コード出力部１１０は、図２に示す期間ｂの始期において、コード値がｎ＋１である第１デジタルコードを出力する。
　Ｄ／Ａ変換器１２０は、コード値がｎ＋１である第１デジタルコードを受けて、当該第１デジタルコードに対応する電圧値のアナログ電圧、すなわち、上述の第２アナログ電圧を差動増幅器１５０に出力する。Ｄ／Ａ変換器１２０から出力される第２アナログ電圧は、所望の電圧値、すなわち、理想的な電圧値に対して誤差を含んでいる。
　以下、Ｄ／Ａ変換器１２０が、コード値がｎ＋１である第１デジタルコードを受けた際に出力するアナログ電圧の電圧値をＶｏｕｔ［ｎ＋１］と表記し、理想的な電圧値である所望の電圧値をＶｉｄｅａｌ［ｎ＋１］と表記する。 Next, the code output unit 110 outputs the first digital code having the code value n + 1 to the D / A converter 120 in the period b shown in FIG. Specifically, for example, the code output unit 110 outputs a first digital code having a code value of n + 1 at the beginning of the period b shown in FIG.
The D / A converter 120 receives the first digital code whose code value is n + 1, and transfers the analog voltage of the voltage value corresponding to the first digital code, that is, the above-mentioned second analog voltage to the differential amplifier 150. Output. The second analog voltage output from the D / A converter 120 contains an error with respect to a desired voltage value, that is, an ideal voltage value.
Hereinafter, the voltage value of the analog voltage output when the D / A converter 120 receives the first digital code whose code value is n + 1 is expressed as Vout [n + 1], and is a desired voltage value which is an ideal voltage value. The voltage value is expressed as Digital [n + 1].
　電圧源１４０は、図２に示す期間ｂにおいて、図２に示す期間ａに出力していた電圧値に等しい電圧値の基準電圧を差動増幅器１５０に出力する。すなわち、電圧源１４０は、図２に示す期間ｂにおいて、電圧値をＶｒｅｆ［ｎ］である基準電圧を出力する。 The voltage source 140 outputs a reference voltage having a voltage value equal to the voltage value output in the period a shown in FIG. 2 to the differential amplifier 150 in the period b shown in FIG. That is, the voltage source 140 outputs a reference voltage whose voltage value is Vref [n] in the period b shown in FIG.
　差動増幅器１５０は、Ｄ／Ａ変換器１２０から出力される電圧値がＶｏｕｔ［ｎ＋１］であるアナログ電圧と、電圧源１４０から出力される電圧値がＶｒｅｆ［ｎ］の基準電圧とを受けて、当該アナログ電圧と当該基準電圧との差電圧を増幅し、増幅差電圧をＡ／Ｄ変換器１６０に出力する。コード値がｎ＋１である第１デジタルコードに対応する差動増幅器１５０が出力する増幅差電圧の電圧値をＶａｍｐ［ｎ＋１］と表記すると、Ｖａｍｐ［ｎ＋１］は、次式（２）で表すことができる。なお、上述のとおり、差動増幅器１５０の増幅率は、Ａであるものとする。
　Ｖａｍｐ［ｎ＋１］＝Ａ×（Ｖｏｕｔ［ｎ＋１］－Ｖｒｅｆ［ｎ］）・・・式（２） The differential amplifier 150 receives an analog voltage whose voltage value output from the D / A converter 120 is Vout [n + 1] and a reference voltage whose voltage value output from the voltage source 140 is Vref [n]. , The difference voltage between the analog voltage and the reference voltage is amplified, and the amplification difference voltage is output to the A / D converter 160. When the voltage value of the amplification difference voltage output by the differential amplifier 150 corresponding to the first digital code whose code value is n + 1 is expressed as Vamp [n + 1], Vamp [n + 1] can be expressed by the following equation (2). it can. As described above, the amplification factor of the differential amplifier 150 is assumed to be A.
Vamp [n + 1] = A × (Vout [n + 1] -Vref [n]) ... Equation (2)
　Ａ／Ｄ変換器１６０は、差動増幅器１５０が出力した電圧値がＶａｍｐ［ｎ＋１］である増幅差電圧を受けて、Ｖａｍｐ［ｎ＋１］に対応する第２デジタルコードを電圧差算出部１７０に出力する。
　電圧差算出部１７０は、Ｖａｍｐ［ｎ＋１］に対応する第２デジタルコードを受けて、当該第２デジタルコードに対応する電圧値を取得することにより、Ｖａｍｐ［ｎ＋１］の値を取得する。 The A / D converter 160 receives the amplification difference voltage whose voltage value output by the differential amplifier 150 is Vamp [n + 1], and outputs the second digital code corresponding to Vamp [n + 1] to the voltage difference calculation unit 170. To do.
The voltage difference calculation unit 170 receives the second digital code corresponding to Vamp [n + 1] and acquires the value of Vamp [n + 1] by acquiring the voltage value corresponding to the second digital code.
　次に、電圧差算出部１７０は、取得したＶａｍｐ［ｎ］の値と、Ｖａｍｐ［ｎ＋１］の値との差を差動増幅器１５０の増幅率であるＡで除することにより、Ｄ／Ａ変換器１２０が出力したコード値がｎである第１デジタルコードに対応する電圧値を有するアナログ電圧と、コード値がｎ＋１である第１デジタルコードに対応する電圧値を有するアナログ電圧との電圧差を出力電圧差として取得する。出力電圧差をΔＶｏｕｔ［ｎ］と表記すると、出力電圧差は、次式（３）で表すことができる。
　ΔＶｏｕｔ［ｎ］＝（Ｖａｍｐ［ｎ＋１］－Ｖａｍｐ［ｎ］）／Ａ・・・式（３） Next, the voltage difference calculation unit 170 converts the D / A by dividing the difference between the acquired value of Vamp [n] and the value of Vamp [n + 1] by A, which is the amplification factor of the differential amplifier 150. The voltage difference between the analog voltage having the voltage value corresponding to the first digital code whose code value is n and the analog voltage having the voltage value corresponding to the first digital code whose code value is n + 1 is calculated by the device 120. Obtained as an output voltage difference. When the output voltage difference is expressed as ΔVout [n], the output voltage difference can be expressed by the following equation (3).
ΔVout [n] = (Vamp [n + 1] -Vamp [n]) / A ... Equation (3)
　次に、誤差算出部１８０は、Ｖｉｄｅａｌ［ｎ］の値と、Ｖｉｄｅａｌ［ｎ＋１］の値との差を算出することにより、コード出力部１１０が、コード値がｎである第１デジタルコードを出力した際にＤ／Ａ変換器１２０が出力するアナログ信号の理想的な電圧値と、コード値がｎ＋１である第１デジタルコードを出力した際にＤ／Ａ変換器１２０が出力するアナログ信号の理想的な電圧値との電圧差（以下「理想電圧差」という。）を算出する。理想電圧差をΔＶｉｄｅａｌ［ｎ］と表記すると、理想電圧差は、次式（４）で表すことができる。
　ΔＶｉｄｅａｌ［ｎ］＝Ｖｉｄｅａｌ［ｎ＋１］－Ｖｉｄｅａｌ［ｎ］・・・式（４） Next, the error calculation unit 180 calculates the difference between the value of the voltage [n] and the value of the voltage [n + 1], so that the code output unit 110 outputs the first digital code having the code value n. The ideal voltage value of the analog signal output by the D / A converter 120 and the ideal analog signal output by the D / A converter 120 when the first digital code whose code value is n + 1 is output. The voltage difference from a typical voltage value (hereinafter referred to as "ideal voltage difference") is calculated. When the ideal voltage difference is expressed as ΔVideal [n], the ideal voltage difference can be expressed by the following equation (4).
ΔVideal [n] = Videal [n + 1] -Videal [n] ... Equation (4)
　次に、誤差算出部１８０は、出力電圧差と理想電圧差との電圧差を算出することにより、コード出力部１１０が、コード値がｎである第１デジタルコードを出力した際と、コード値がｎ＋１である第１デジタルコードを出力した際との間に生じるＤＮＬを算出する。コード出力部１１０が、コード値がｎである第１デジタルコードを出力した際と、コード値がｎ＋１である第１デジタルコードを出力した際との間に生じるＤＮＬをＤＮＬ［ｎ］と表記すると、ＤＮＬ［ｎ］は、次式（５）で表すことができる。
　ＤＮＬ［ｎ］＝ ΔＶｏｕｔ［ｎ］－ΔＶｉｄｅａｌ［ｎ］・・・式（５） Next, the error calculation unit 180 calculates the voltage difference between the output voltage difference and the ideal voltage difference, so that the code output unit 110 outputs the first digital code whose code value is n, and the code value. The DNL generated between the time when the first digital code in which is n + 1 is output is calculated. When the code output unit 110 outputs the first digital code having the code value n and the first digital code having the code value n + 1, the DNL generated between the output is expressed as DNL [n]. , Digital [n] can be expressed by the following equation (5).
DNL [n] = ΔVout [n] −ΔVideal [n] ... Equation (5)
　図３は、実施の形態１に係る誤差検出回路１００における差動増幅器１５０が出力する増幅差電圧の電圧値の時間変化の一例を示す図である。
　図３において、横軸は時間を示し、縦軸は増幅差電圧の電圧値を示している。
　また、図３において、実線は、Ｄ／Ａ変換器１２０が出力したＤＮＬを含むアナログ電圧を受けて、差動増幅器１５０が出力する増幅差電圧の電圧値の時間変化を示したものである。
　また、図３において、破線は、Ｄ／Ａ変換器１２０がＤＮＬを含まない理想的なアナログ電圧を受けて、差動増幅器１５０が増幅差電圧を出力する場合の理想的な増幅差電圧の電圧値の時間変化を示したものである。
　また、図３において、横軸の下に示す数字は、コード出力部１１０が出力する第１デジタルコードのコード値を示している。 FIG. 3 is a diagram showing an example of a time change of the voltage value of the amplification difference voltage output by the differential amplifier 150 in the error detection circuit 100 according to the first embodiment.
In FIG. 3, the horizontal axis represents time and the vertical axis represents the voltage value of the amplification difference voltage.
Further, in FIG. 3, the solid line shows the time change of the voltage value of the amplification difference voltage output by the differential amplifier 150 in response to the analog voltage including the DNL output by the D / A converter 120.
Further, in FIG. 3, the broken line indicates the voltage of the ideal amplification difference voltage when the D / A converter 120 receives the ideal analog voltage not including the DNL and the differential amplifier 150 outputs the amplification difference voltage. It shows the time change of the value.
Further, in FIG. 3, the numbers shown below the horizontal axis indicate the code values of the first digital code output by the code output unit 110.
　Ｄ／Ａ変換器１２０が実際に出力するアナログ電圧の電圧値を示すＶｏｕｔ［ｎ］は、理想的なアナログ電圧の電圧値であるＶｉｄｅａｌ［ｎ］と比較して、ＤＮＬを含むため、差動増幅器１５０が出力する増幅差電圧の電圧値であるＶａｍｐ［ｎ］も、ＤＮＬを含むものとなる。増幅差電圧は、Ｄ／Ａ変換器１２０が出力するアナログ電圧と基準電圧との差電圧が、差動増幅器１５０により十分に増幅されたものであるため、Ｖａｍｐ［ｎ］に含まれるＤＮＬは、Ｖｏｕｔ［ｎ］に含まれるＤＮＬと比較して大きな値を示す。そのため、Ｖｏｕｔ［ｎ］に含まれるＤＮＬがＡ／Ｄ変換器１６０の分解能より小さくＤＮＬが検知できない場合であっても、Ｖｏｕｔ［ｎ］に含まれるＤＮＬより大きな値を示すＶａｍｐ［ｎ］に含まれるＤＮＬは、Ｖａｍｐ［ｎ］に含まれるＤＮＬが当該Ａ／Ｄ変換器１６０の分解能より大きい場合、ＤＮＬを検知できるようになる。 Vout [n], which indicates the voltage value of the analog voltage actually output by the D / A converter 120, contains DNL as compared with the ideal analog voltage voltage value, which is a differential. The Vamp [n], which is the voltage value of the amplification difference voltage output by the amplifier 150, also includes the DNL. Since the amplification difference voltage is the difference voltage between the analog voltage output by the D / A converter 120 and the reference voltage that is sufficiently amplified by the differential amplifier 150, the DNL included in Vamp [n] is It shows a large value as compared with the DNL contained in Vout [n]. Therefore, even if the DNL contained in the Vout [n] is smaller than the resolution of the A / D converter 160 and the DNL cannot be detected, it is included in the Vamp [n] showing a value larger than the DNL contained in the Vout [n]. When the DNL contained in the Vamp [n] is larger than the resolution of the A / D converter 160, the DNL can detect the DNL.
　式（５）に式（１）から式（３）を代入すると、式（５）に示すＤＮＬ［ｎ］は、次式（６）で表すことができる。
　ＤＮＬ［ｎ］＝（Ｖａｍｐ［ｎ＋１］－Ｖａｍｐ［ｎ］）／Ａ
　　　　　　　　－Ｖｉｄｅａｌ［ｎ］
　　　　　　　＝｛Ａ×（Ｖｏｕｔ［ｎ＋１］－Ｖｒｅｆ［ｎ］）
　　　　　　　　　－Ａ×（Ｖｏｕｔ［ｎ］－Ｖｒｅｆ［ｎ］）｝／Ａ
　　　　　　　　－Ｖｉｄｅａｌ［ｎ］
　　　　　　　＝（Ｖｏｕｔ［ｎ＋１］－Ｖｏｕｔ［ｎ］）
　　　　　　　　－Ｖｉｄｅａｌ［ｎ］・・・式（６） Substituting the equations (1) to (3) into the equation (5), the DNL [n] shown in the equation (5) can be expressed by the following equation (6).
DNL [n] = (Vamp [n + 1] -Vamp [n]) / A
-Visual [n]
= {A × (Vout [n + 1] -Vref [n])
-Ax (Vout [n] -Vref [n])} / A
-Visual [n]
= (Vout [n + 1] -Vout [n])
-Visual [n] ... Equation (6)
　式（６）に示すように、ＤＮＬ［ｎ］の計算の過程において、基準電圧の電圧値を示すＶｒｅｆ[ｎ]の項が消えるため、ＤＮＬ［ｎ］の値は、基準電圧の影響を受けないことが分かる。すなわち、誤差検出回路１００は、コード出力部１１０が、コード値がｎである第１デジタルコードをＤ／Ａ変換器１２０に出力する際と、コード出力部１１０が、コード値がｎ＋１である第１デジタルコードをＤ／Ａ変換器１２０に出力する際とにおいて、電圧源１４０が出力する基準電圧の電圧値を一定にするように制御することにより、電圧源１４０が出力する基準電圧の精度に依存することなく、ＤＮＬ［ｎ］を検出することができる。 As shown in equation (6), in the process of calculating DNL [n], the term of Vref [n] indicating the voltage value of the reference voltage disappears, so that the value of DNL [n] is affected by the reference voltage. It turns out that there is no. That is, in the error detection circuit 100, when the code output unit 110 outputs the first digital code having the code value n to the D / A converter 120, the code output unit 110 has the code value n + 1. 1 When the digital code is output to the D / A converter 120, the accuracy of the reference voltage output by the voltage source 140 is improved by controlling the voltage value of the reference voltage output by the voltage source 140 to be constant. DNL [n] can be detected independently.
　これまで、コード出力部１１０が、コード値がｎである第１デジタルコードを出力した際と、コード値がｎ＋１である第１デジタルコードを出力した際との間に生じるＤＮＬ［ｎ］を検出する一連の動作について説明した。誤差検出回路１００は、上述の動作と同様の動作を行うことにより、コード出力部１１０が、任意の第１コードを有する第１デジタルコードを出力した際と、当該第１コードに隣接する第２コードを有する第１デジタルコードを出力した際との間に生じるＤＮＬを検出することができる。 So far, the code output unit 110 has detected the DNL [n] that occurs between the time when the first digital code whose code value is n is output and the time when the first digital code whose code value is n + 1 is output. A series of operations to be performed has been explained. The error detection circuit 100 performs the same operation as the above operation, so that when the code output unit 110 outputs a first digital code having an arbitrary first code, and when the second code adjacent to the first code is output. It is possible to detect the DNL that occurs when the first digital code having the code is output.
　以上のように、誤差検出回路１００は、出力電圧値を示す第１デジタルコードを出力するコード出力部１１０と、コード出力部１１０が出力した第１デジタルコードを受けて、第１デジタルコードに対応するアナログ電圧を出力するＤ／Ａ変換器１２０と、制御信号を出力する制御出力部１３０と、制御出力部１３０が出力した制御信号を受けて、制御信号に対応する基準電圧を出力する電圧源１４０と、Ｄ／Ａ変換器１２０が出力したアナログ電圧と、電圧源１４０が出力した基準電圧とを受けて、アナログ電圧と基準電圧との差電圧を増幅して、増幅後の差電圧を出力する差動増幅器１５０と、差動増幅器１５０が出力した増幅後の差電圧を受けて、増幅後の差電圧に対応する第２デジタルコードを出力するＡ／Ｄ変換器１６０と、Ａ／Ｄ変換器１６０が出力した第２デジタルコードを受けて、第１コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第１アナログ電圧に対応する第２デジタルコードと、第１コード値に隣接する値である第２コード値を有する第１デジタルコードに対応してＤ／Ａ変換器１２０が出力した第２アナログ電圧に対応する第２デジタルコードとに基づいて、Ｄ／Ａ変換器１２０が出力した第１アナログ電圧と第２アナログ電圧との電圧差を出力電圧差として算出する電圧差算出部１７０と、第１コード値を有する第１デジタルコードが示す出力電圧値と、第２コード値を有する第１デジタルコードが示す出力電圧値との電圧差に基づいて、電圧差算出部１７０が算出した出力電圧差の誤差を算出する誤差算出部１８０と、を備え、制御出力部１３０は、電圧差算出部１７０が、第１コード値を有する第１デジタルコードに対応する第２デジタルコードと、第２コード値に対応する第２デジタルコードとを受けるまでの期間において、電圧源１４０が出力する基準電圧を一定に保つ制御信号を出力するように構成した。 As described above, the error detection circuit 100 receives the code output unit 110 that outputs the first digital code indicating the output voltage value and the first digital code output by the code output unit 110, and corresponds to the first digital code. A D / A converter 120 that outputs an analog voltage, a control output unit 130 that outputs a control signal, and a voltage source that receives a control signal output by the control output unit 130 and outputs a reference voltage corresponding to the control signal. In response to the 140, the analog voltage output by the D / A converter 120, and the reference voltage output by the voltage source 140, the difference voltage between the analog voltage and the reference voltage is amplified, and the amplified difference voltage is output. A / D converter 160 that receives the difference voltage after amplification output by the differential amplifier 150 and outputs a second digital code corresponding to the difference voltage after amplification, and A / D conversion. Upon receiving the second digital code output by the device 160, the second digital code corresponding to the first analog voltage output by the D / A converter 120 corresponding to the first digital code having the first code value, and the second digital code. Based on the second digital code corresponding to the second analog voltage output by the D / A converter 120 corresponding to the first digital code having the second code value which is a value adjacent to the 1 code value, D / The voltage difference calculation unit 170 that calculates the voltage difference between the first analog voltage and the second analog voltage output by the A converter 120 as the output voltage difference, and the output voltage value indicated by the first digital code having the first code value. , An error calculation unit 180 that calculates an error of the output voltage difference calculated by the voltage difference calculation unit 170 based on the voltage difference from the output voltage value indicated by the first digital code having the second code value, and controls. The output unit 130 takes a period until the voltage difference calculation unit 170 receives the second digital code corresponding to the first digital code having the first code value and the second digital code corresponding to the second code value. It is configured to output a control signal that keeps the reference voltage output by the voltage source 140 constant.
　このように構成することにより、誤差検出回路１００は、高い分解能を有していないＡ／Ｄ変換器１６０であっても、Ｄ／Ａ変換器１２０が出力するアナログ電圧の電圧値の間隔に含まれるＤＮＬを高い精度で検出できる。
　したがって、例えば、特許文献１に記載された電圧制御発振器を制御対象として、誤差検出回路１００の出力端子１９９を当該電圧制御発振器に接続する場合、誤差検出回路１００は、特許文献１に記載されたレーダ装置の測定精度を高めることができる。
　また、このように構成することにより、誤差検出回路１００は、基準電圧の精度に依存することなく、高い精度でＤＮＬを検出することができる。 With this configuration, the error detection circuit 100 is included in the interval between the voltage values of the analog voltage output by the D / A converter 120 even if the A / D converter 160 does not have high resolution. The DNL can be detected with high accuracy.
Therefore, for example, when the output terminal 199 of the error detection circuit 100 is connected to the voltage controlled oscillator with the voltage controlled oscillator described in Patent Document 1 as the control target, the error detection circuit 100 is described in Patent Document 1. The measurement accuracy of the radar device can be improved.
Further, with this configuration, the error detection circuit 100 can detect the DNL with high accuracy without depending on the accuracy of the reference voltage.
　また、誤差検出回路１００は、上述の構成において、制御出力部１３０は、コード出力部１１０が出力した第１デジタルコードに対応する制御信号を出力し、電圧源１４０は、制御信号に対応する第１デジタルコードが示す出力電圧値に相当する基準電圧を出力するように構成した。
　このように構成することにより、差動増幅器１５０の増幅率を高めることができるため、誤差検出回路１００は、高い分解能を有していないＡ／Ｄ変換器１６０であっても、Ｄ／Ａ変換器１２０が出力するアナログ電圧の電圧値の間隔に含まれるＤＮＬをより高い精度で検出できる。 Further, in the above-described configuration, the error detection circuit 100 outputs a control signal corresponding to the first digital code output by the code output unit 110, and the voltage source 140 corresponds to the control signal. 1 It is configured to output a reference voltage corresponding to the output voltage value indicated by the digital code.
With this configuration, the amplification factor of the differential amplifier 150 can be increased, so that the error detection circuit 100 can perform D / A conversion even if the A / D converter 160 does not have high resolution. The DNL included in the interval between the voltage values of the analog voltage output by the device 120 can be detected with higher accuracy.
　また、誤差検出回路１００は、上述の構成において、電圧源１４０を、第１デジタルコードに対応するアナログ電圧を出力するＤ／Ａ変換器１２０とは異なる、第２のＤ／Ａ変換器により構成しても良い。
　このように構成することにより、制御出力部１３０は、コード出力部１１０が出力する第１デジタルコードに相当するデジタルコードを制御信号として出力することができるため、制御出力部１３０は、第１デジタルコードに対応する制御信号を生成する必要がなくなる。 Further, in the above configuration, the error detection circuit 100 includes the voltage source 140 with a second D / A converter, which is different from the D / A converter 120 that outputs an analog voltage corresponding to the first digital code. You may.
With this configuration, the control output unit 130 can output a digital code corresponding to the first digital code output by the code output unit 110 as a control signal, so that the control output unit 130 can output the first digital. There is no need to generate a control signal corresponding to the code.
　また、誤差検出回路１００は、上述の構成に加えて、Ｄ／Ａ変換器１２０が出力するアナログ電圧を受けて、当該アナログ電圧に含まれるノイズ信号を減衰させ、ノイズ信号を低減させた後のアナログ電圧を差動増幅器１５０に出力するローパスフィルタ１９０を備えたものであっても良い。
　このように構成することにより、誤差検出回路１００は、ノイズ信号が低減されたアナログ電圧を制御対象に出力でき、且つ、Ｄ／Ａ変換器１２０が出力するアナログ電圧に含まれるＤＮＬに加えて、ローパスフィルタ１９０による出力電圧の誤差も検出できる。
　なお、ローパスフィルタ１９０が、ノイズ信号が低減されたアナログ電圧により制御対象を制御するためだけに備えられるものである場合、ローパスフィルタ１９０は、出力端子１９９と制御対象との間に配置されたものであっても、制御対象の内部に配置されたものであっても良い。 Further, in addition to the above configuration, the error detection circuit 100 receives the analog voltage output by the D / A converter 120, attenuates the noise signal included in the analog voltage, and reduces the noise signal. It may be provided with a low-pass filter 190 that outputs an analog voltage to the differential amplifier 150.
With this configuration, the error detection circuit 100 can output an analog voltage with a reduced noise signal to the control target, and in addition to the DNL included in the analog voltage output by the D / A converter 120, An error in the output voltage due to the low-pass filter 190 can also be detected.
When the low-pass filter 190 is provided only for controlling the control target by the analog voltage in which the noise signal is reduced, the low-pass filter 190 is arranged between the output terminal 199 and the control target. However, it may be arranged inside the controlled object.
　なお、この発明はその発明の範囲内において、各実施の形態の自由な組み合わせ、あるいは各実施の形態の任意の構成要素の変形、もしくは各実施の形態において任意の構成要素の省略が可能である。 It should be noted that, within the scope of the present invention, any combination of the embodiments can be freely combined, any component of the embodiment can be modified, or any component can be omitted in each embodiment. ..
　この発明に係る誤差検出回路は、電子機器に適用することができる。 The error detection circuit according to the present invention can be applied to electronic devices.
　１００　誤差検出回路、１１０　コード出力部、１２０　Ｄ／Ａ変換器、１３０　制御出力部、１４０　電圧源、１５０　差動増幅器、１６０　Ａ／Ｄ変換器、１７０　電圧差算出部、１８０　誤差算出部、１９０　ローパスフィルタ、１９９　出力端子。 100 error detection circuit, 110 code output unit, 120 D / A converter, 130 control output unit, 140 voltage source, 150 differential amplifier, 160 A / D converter, 170 voltage difference calculation unit, 180 error calculation unit, 190 Low-pass filter, 199 output terminal.

Claims (3)

  1. 　出力電圧値を示す第１デジタルコードを出力するコード出力部と、
    　前記コード出力部が出力した前記第１デジタルコードを受けて、前記第１デジタルコードに対応するアナログ電圧を出力するＤ／Ａ変換器と、
    　制御信号を出力する制御出力部と、
    　前記制御出力部が出力した前記制御信号を受けて、前記制御信号に対応する基準電圧を出力する電圧源と、
    　前記Ｄ／Ａ変換器が出力した前記アナログ電圧と、前記電圧源が出力した前記基準電圧とを受けて、前記アナログ電圧と前記基準電圧との差電圧を増幅して、増幅後の前記差電圧を出力する差動増幅器と、
    　前記差動増幅器が出力した増幅後の前記差電圧を受けて、増幅後の前記差電圧に対応する第２デジタルコードを出力するＡ／Ｄ変換器と、
    　前記Ａ／Ｄ変換器が出力した前記第２デジタルコードを受けて、第１コード値を有する前記第１デジタルコードに対応して前記Ｄ／Ａ変換器が出力した第１アナログ電圧に対応する前記第２デジタルコードと、前記第１コード値に隣接する値である第２コード値を有する前記第１デジタルコードに対応して前記Ｄ／Ａ変換器が出力した第２アナログ電圧に対応する前記第２デジタルコードとに基づいて、前記Ｄ／Ａ変換器が出力した前記第１アナログ電圧と前記第２アナログ電圧との電圧差を出力電圧差として算出する電圧差算出部と、
    　前記第１コード値を有する前記第１デジタルコードが示す前記出力電圧値と、前記第２コード値を有する前記第１デジタルコードが示す前記出力電圧値との電圧差に基づいて、前記電圧差算出部が算出した前記出力電圧差の誤差を算出する誤差算出部と、
    　を備え、
    　前記制御出力部は、前記電圧差算出部が、前記第１コード値を有する前記第１デジタルコードに対応する前記第２デジタルコードと、前記第２コード値に対応する前記第２デジタルコードとを受けるまでの期間において、前記電圧源が出力する前記基準電圧を一定に保つ前記制御信号を出力すること
    　を特徴とする誤差検出回路。     A code output unit that outputs the first digital code that indicates the output voltage value,
    A D / A converter that receives the first digital code output by the code output unit and outputs an analog voltage corresponding to the first digital code.
    A control output unit that outputs control signals and
    A voltage source that receives the control signal output by the control output unit and outputs a reference voltage corresponding to the control signal.
    In response to the analog voltage output by the D / A converter and the reference voltage output by the voltage source, the difference voltage between the analog voltage and the reference voltage is amplified, and the difference voltage after amplification is amplified. With a differential amplifier that outputs
    An A / D converter that receives the amplified differential voltage output by the differential amplifier and outputs a second digital code corresponding to the amplified differential voltage.
    In response to the second digital code output by the A / D converter, the first analog voltage output by the D / A converter corresponding to the first digital code having the first code value is supported. The second digital code and the second analog voltage corresponding to the second analog voltage output by the D / A converter corresponding to the first digital code having the second code value which is a value adjacent to the first code value. A voltage difference calculation unit that calculates the voltage difference between the first analog voltage and the second analog voltage output by the D / A converter as an output voltage difference based on the two digital codes.
    The voltage difference is calculated based on the voltage difference between the output voltage value indicated by the first digital code having the first code value and the output voltage value indicated by the first digital code having the second code value. An error calculation unit that calculates the error of the output voltage difference calculated by the unit, and
    With
    In the control output unit, the voltage difference calculation unit has the second digital code corresponding to the first digital code having the first code value and the second digital code corresponding to the second code value. An error detection circuit characterized by outputting the control signal that keeps the reference voltage output by the voltage source constant during the period until the voltage is received.
  2. 　前記制御出力部は、前記コード出力部が出力した前記第１デジタルコードに対応する前記制御信号を出力し、
    　前記電圧源は、前記制御信号に対応する前記第１デジタルコードが示す前記出力電圧値に相当する前記基準電圧を出力すること
    　を特徴とする請求項１記載の誤差検出回路。     The control output unit outputs the control signal corresponding to the first digital code output by the code output unit, and outputs the control signal.
    The error detection circuit according to claim 1, wherein the voltage source outputs the reference voltage corresponding to the output voltage value indicated by the first digital code corresponding to the control signal.
  3. 　前記電圧源は、前記第１デジタルコードに対応する前記アナログ電圧を出力する前記Ｄ／Ａ変換器とは異なる、第２のＤ／Ａ変換器により構成されたこと
    　を特徴とする請求項１又は請求項２記載の誤差検出回路。     Claim 1 or claim 1, wherein the voltage source is composed of a second D / A converter different from the D / A converter that outputs the analog voltage corresponding to the first digital code. The error detection circuit according to claim 2.
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Publication number Priority date Publication date Assignee Title
JPS58172560A (en) * 1982-04-02 1983-10-11 Fujitsu Ltd Linearity measurement of d/a converter
JPS60219816A (en) * 1984-04-17 1985-11-02 Fujitsu Ltd Circuit for measuring linearity error of digital-analog converter
JPH09246968A (en) * 1996-03-06 1997-09-19 Rohm Co Ltd Measuring method for characteristic of d/a converter and measuring unit for characteristic of d/a converter
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