JP2008286699A - Signal input and output device, testing device, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal input and output device for precisely inputting analog signals. <P>SOLUTION: This signal input and output device for the analog signal is provided with a D/A conversion part for outputting the analog signal, in response to an imparted input waveform data; an output circuit for transmitting the analog signal output from the D/A conversion part to an output terminal, an A/D conversion part for outputting an output waveform data in response to the imparted analog signal; an input circuit for transmitting the analog signal input via the input terminal to the A/D conversion part; a switching control part for imparting a predetermined reference waveform data to the D/A conversion part, in place of the input waveform data when the characteristics are measured, and for supplying a signal between the D/A conversion part and the output circuit, to the input circuit, rather than the analog signal; an acquisition part for acquiring the output waveform data output from the A/D conversion part as a measured waveform data, when measuring the characteristic, and a calculation part for calculating transmission characteristics of the input circuit and the A/D conversion part, based on the reference waveform data and the measured waveform data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a signal input / output device, a test apparatus, and an electronic device. In particular, the present invention relates to a signal input / output apparatus, a test apparatus, and an electronic device for analog signals.

  2. Description of the Related Art A test apparatus is known that includes a signal generator that supplies an analog signal having an arbitrary waveform to a device under test and a digitizer that takes in and digitizes the waveform of the analog signal output from the device under test (for example, Patent Documents). 1). According to such a test apparatus, an electronic device that inputs and outputs analog signals can be tested.

Such a test apparatus corrects the waveform data captured by the digitizer according to the transfer characteristics of the path from the input terminal for inputting an analog signal to the AD converter in the digitizer. As a result, according to the test apparatus, it is possible to remove signal degradation that occurs in the path from the input terminal of the digitizer to the AD converter from the captured waveform data.
JP 2006-337140 A

  Incidentally, the transfer characteristic of the path from the input terminal of the digitizer to the AD converter must be measured in advance by a network analyzer. Therefore, the user must connect the probe of the network analyzer to the input terminal of the test apparatus and the AD converter and measure the transfer characteristics at the time of calibration, for example. For this reason, according to such a test apparatus, the number of work steps for measuring the transfer characteristics is large.

  Further, the network analyzer cannot measure the transfer characteristic of a route to a part where the probe cannot be connected (for example, the transfer characteristic of the route to the middle of the IC). Therefore, the network analyzer cannot measure the transfer characteristic of the path including the internal circuit of the AD converter.

  Moreover, it is difficult for the network analyzer to input a differential signal. Therefore, when the AD converter is a differential input and a differential amplifier for converting a single-ended signal into a differential signal is provided in the previous stage of the AD converter, the network analyzer includes the differential amplifier. It was difficult to accurately measure the transfer characteristics of the path.

  Therefore, an object of the present invention is to provide a signal input / output apparatus, a test apparatus, and an electronic device that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  In order to solve the above-described problem, in the first embodiment of the present invention, a signal input / output device for an analog signal, a DA converter that outputs an analog signal corresponding to given input waveform data, and a DA converter An output circuit for transmitting an analog signal output from the output unit to an output terminal, an AD converter for outputting output waveform data corresponding to the given analog signal, and an analog signal input via the input terminal to the AD converter In the characteristic measurement, the reference waveform data determined in advance instead of the input waveform data is given to the DA converter, and the analog signal from the input terminal is replaced with the analog signal from the DA converter and the output circuit. A switching control unit that supplies a signal to the input circuit, an acquisition unit that acquires output waveform data output from the AD conversion unit as measurement waveform data during characteristic measurement, and a reference wave Based on the data and the measured waveform data, to provide a signal output device and a calculation unit for calculating a transfer characteristic of the input circuit and the AD converter.

  In the second embodiment of the present invention, a DA converter for testing a device under test, which outputs an analog signal corresponding to input waveform data representing a waveform of a test signal to be supplied to the device under test; , An output circuit for transmitting the analog signal output from the DA converter to the device under test, an AD converter for outputting output waveform data corresponding to the given analog signal, and the analog signal output from the device under test The input circuit that transmits to the AD converter, the corrector that corrects the output waveform data according to the inverse characteristics of the transfer characteristics of the input circuit and the AD converter, and the quality of the device under test based on the corrected output waveform data And a reference waveform data set in advance in place of the input waveform data to the DA converter during the characteristic measurement. A switching control unit that supplies a signal between the DA conversion unit and the output circuit to the input circuit instead of the log signal, and acquisition of the output waveform data output by the AD conversion unit as measurement waveform data during characteristic measurement A test apparatus is provided that includes a calculation unit that calculates a transfer characteristic of an input circuit and an AD conversion unit based on a reference waveform data and measurement waveform data.

  According to a third aspect of the present invention, an electronic device includes a circuit under test and a test circuit for testing the circuit under test, and the test circuit represents a waveform of a test signal to be supplied to the circuit under test. A DA converter that outputs an analog signal corresponding to the input waveform data, an output circuit that transmits the analog signal output from the DA converter to the circuit under test, and output waveform data corresponding to the given analog signal An AD converter, an input circuit that transmits an analog signal output from the circuit under test to the AD converter, and a correction unit that corrects the output waveform data according to the reverse characteristics of the transfer characteristics of the input circuit and the AD converter; A determination unit for determining the quality of the circuit under test based on the corrected output waveform data, and a reference waveform data set in advance in place of the input waveform data at the time of characteristic measurement in the DA conversion unit A switching control unit for supplying a signal between the DA conversion unit and the output circuit to the input circuit instead of an analog signal from the circuit under test, and output waveform data output by the AD conversion unit during the characteristic measurement. An electronic device is provided that includes an acquisition unit that acquires measurement waveform data, and a calculation unit that calculates transfer characteristics of an input circuit and an AD conversion unit based on reference waveform data and measurement waveform data.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows a configuration of a test apparatus 10 according to the present embodiment, together with a device under test 300. FIG. 2 shows an example of the configuration of the output circuit 36 shown in FIG.

  The test apparatus 10 tests the device under test 300 that inputs and outputs analog signals. More specifically, the test apparatus 10 supplies an analog test signal to the device under test 300 and takes in an analog output signal output from the device under test 300 according to the test signal. Then, the test apparatus 10 compares the captured waveform of the output signal with the expected waveform to determine whether the device under test 300 is good or bad.

  The test apparatus 10 includes a waveform memory 12, a transfer unit 14, a determination unit 16, and a signal input / output device 20. The waveform memory 12 stores waveform data (input waveform data) representing the waveform of the test signal to be supplied to the device under test 300. As an example, the test apparatus 10 stores a series of signal values obtained by sampling an arbitrary waveform such as a sine wave and a ramp wave at a predetermined pitch as input waveform data.

  The transfer unit 14 sequentially reads the input waveform data stored in the waveform memory 12 and transfers it to the signal input / output device 20. For example, the transfer unit 14 may read the input waveform data in the order according to the list. The determination unit 16 compares the waveform of the output signal of the device under test 300 captured by the signal input / output device 20 with the expected waveform. Then, the determination unit 16 determines pass / fail of the device under test 300 based on the comparison result.

  The signal input / output device 20 includes a first switching unit 32, a DA conversion unit 34, an output circuit 36, a second switching unit 42, an input circuit 44, an AD conversion unit 46, a correction unit 48, and a reference waveform. The generation unit 52, the switching control unit 54, the acquisition unit 56, and the calculation unit 58 are included. During the test, the signal input / output device 20 generates an analog test signal having a waveform corresponding to the input waveform data given from the transfer unit 14 and supplies the analog test signal to the device under test 300 via the output terminal 26. Further, the signal input / output device 20 inputs an analog output signal output from the device under test 300 via the input terminal 28 during the test, digitizes the input output signal, and captures the waveform of the output signal. .

  Further, the signal input / output device 20 measures the characteristics of the signal input / output device 20 for the purpose of calibration, for example, at regular intervals or before the start of the test. At the time of characteristic measurement, the signal input / output device 20 measures the transmission characteristic of the signal path from the input terminal 28 to the output end of the AD conversion unit 46.

  The first switching unit 32 selects one of the input waveform data output from the transfer unit 14 or the reference waveform data output from the reference waveform generation unit 52 and supplies the selected waveform data to the DA conversion unit 34. More specifically, the first switching unit 32 selects input waveform data at the time of testing and supplies it to the DA conversion unit 34, and selects reference waveform data at the time of characteristic measurement and supplies it to the DA conversion unit 34.

  The DA converter 34 outputs an analog signal corresponding to the given waveform data. More specifically, the DA conversion unit 34 outputs an analog signal corresponding to the input waveform data by performing DA conversion on the input waveform data given from the transfer unit 14 during the test. Further, the DA converter 34 outputs an analog signal corresponding to the reference waveform data by performing DA conversion on the reference waveform data given from the reference waveform generator 52 instead of the input waveform data at the time of characteristic measurement. .

  As an example, the DA converter 34 may include a differential DAC 342 and a transformer 344. The differential DAC 342 outputs a differential signal corresponding to the given waveform data. The transformer 344 converts the differential signal output from the differential DAC 342 into a single-ended signal.

  The output circuit 36 transmits the analog signal output from the DA converter 34 to the device under test 300 via the output terminal 26. For example, the output circuit 36 may be a band limiting circuit. That is, for example, the output circuit 36 may supply the device under test 300 with a signal in which the band of the analog signal output from the DA converter 34 is limited.

  As an example, the output circuit 36 may include a band limiting circuit 60 including a first attenuator 62, a filter circuit 64, a second attenuator 66, and an amplifier 68 as shown in FIG. The first attenuator 62 attenuates the analog signal output from the DA converter 34. The filter circuit 64 filters the analog signal attenuated by the first attenuator 62. The second attenuator 66 attenuates the analog signal filtered by the filter circuit 64. The amplifier 68 amplifies the analog signal attenuated by the second attenuator 66. Thereby, according to the band limiting circuit 60, a signal obtained by band limiting the analog signal output from the DA converter 34 can be given to the device under test 300.

  The second switching unit 42 selects one of the analog signal output from the device under test 300 or the analog signal output from the DA conversion unit 34 and supplies the selected analog signal to the input circuit 44. More specifically, the second switching unit 42 selects an analog signal output from the device under test 300 at the time of testing and applies it to the input circuit 44, and selects the analog signal output from the DA conversion unit 34 at the time of characteristic measurement. To the input circuit 44.

  The input circuit 44 transmits the analog signal input via the second switching unit 42 to the AD conversion unit 46. More specifically, the input circuit 44 inputs an analog signal output from the device under test 300 via the input terminal 28 and transmits the input analog signal to the AD conversion unit 46 during the test. The input circuit 44 inputs the analog signal output from the DA conversion unit 34 and transmits the input analog signal to the AD conversion unit 46 at the time of characteristic measurement. For example, the input circuit 44 may limit the band of the analog signal to be transmitted. That is, for example, the input circuit 44 may supply the AD converter 46 with an analog signal output from the device under test 300 or a signal in which the band of the analog signal output from the DA converter 34 is limited.

  The AD converter 46 outputs output waveform data corresponding to the analog signal supplied from the input circuit 44. More specifically, the AD converter 46 DA-converts the analog signal output from the device under test 300 and passed through the input circuit 44 during the test, and outputs output waveform data obtained as a result of the DA conversion. Further, the AD conversion unit 46 DA-converts the analog signal output from the DA conversion unit 34 and passed through the input circuit 44 at the time of characteristic measurement, and outputs output waveform data obtained as a result of the DA conversion.

  As an example, the AD conversion unit 46 may include a differential amplifier 462 and a differential ADC 464. The differential amplifier 462 converts the single end signal output from the input circuit 44 into a differential signal. The differential ADC 464 outputs a digital signal corresponding to the differential signal output from the differential amplifier 462.

  The correction unit 48 corrects the output waveform data according to the inverse characteristics of the transfer characteristics of the input circuit 44 and the AD conversion unit 46. That is, the correction unit 48 corrects the output waveform data output from the AD conversion unit 46 according to the reverse characteristic of the transfer characteristic of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46.

As an example, the correction unit 48 may correct the output waveform data based on the S parameter of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46. For example, the correction unit 48 may decompose the output waveform data for each frequency component, and correct each frequency component with the S parameter of the corresponding frequency. Correcting unit 48, as an example, the frequency components of the output waveform data, may be corrected by dividing by a factor S ₂₁ of S parameters of the corresponding frequency. As a result, the correction unit 48 can output output waveform data in which signal degradation occurring in the input circuit 44 and the AD conversion unit 46 is corrected.

  Then, the correction unit 48 supplies the corrected output waveform data to the determination unit 16. Thereby, the determination unit 16 can determine the quality of the device under test 300 based on the output waveform data corrected by the correction unit 48.

  The reference waveform generator 52 generates predetermined reference waveform data at the time of characteristic measurement. In the present embodiment, the reference waveform generator 52 generates a series of signal values of a waveform (multitone signal) including a plurality of frequency components as reference waveform data.

  The switching control unit 54 controls the first switching unit 32 and the second switching unit 42. More specifically, the switching control unit 54 switches the first switching unit 32 so that the input waveform data output from the transfer unit 14 is supplied to the DA conversion unit 34 during the test, and the analog signal from the device under test 300 is switched. Is switched to the input circuit 44. Further, the switching control unit 54 switches the first switching unit 32 so as to provide the DA converter 34 with predetermined reference waveform data instead of the input waveform data at the time of characteristic measurement, and the analog from the device under test 300 is switched. The second switching unit 42 is switched so that a signal between the DA converter 34 and the output circuit 36 is supplied to the input circuit 44 instead of the signal.

  The acquisition unit 56 acquires the output waveform data output from the AD conversion unit 46 as measurement waveform data during characteristic measurement. That is, the acquisition unit 56 acquires a series of signal values obtained as a result of sampling the analog signal output from the DA conversion unit 34 and passed through the input circuit 44 by the AD conversion unit 46 as measurement waveform data.

  The calculation unit 58 calculates transfer characteristics of the input circuit 44 and the AD conversion unit 46 based on the reference waveform data and the measurement waveform data. That is, the calculation unit 58 calculates the transfer characteristic of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46 based on the reference waveform data and the measurement waveform data. For example, the calculation unit 58 may calculate the S parameter of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46 as a transfer characteristic.

  Then, the calculation unit 58 calculates the reverse characteristic of the transfer characteristic of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46, and gives the calculated reverse characteristic to the correction unit 48. For example, the calculation unit 58 may provide the correction unit 48 with the S parameter of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46.

  According to the test apparatus 10 having the above configuration, transfer characteristics from the input terminal 28 to the output end of the correction unit 48 can be measured without using a network analyzer. Thereby, according to the test apparatus 10, the measurement of a transfer characteristic can be automated and work processes can be reduced.

  Further, according to the test apparatus 10, it is possible to measure the transfer characteristics of the path including the internal circuit of the correction unit 48. Further, according to the test apparatus 10, even when the correction unit 48 includes the differential ADC 464 and the differential amplifier 462, transmission characteristics including these can be measured. Thereby, according to the test apparatus 10, the transfer characteristic from the input terminal 28 to the output terminal of the correction | amendment part 48 can be measured with a sufficient precision.

FIG. 3 shows a two-port network 70 formed during characteristic measurement. At the time of characteristic measurement, a two-port network 70 including a DA converter 34, an input circuit 44, and an AD converter 46 is formed in the signal input / output device 20. When the input signal level for the input port 72 of the two-port network 70 is a ₁ , the output signal level is b ₁ , the input signal level for the output port 74 is a ₂ , and the output signal level is b ₂ , The S parameter of the 2-port network 70 is expressed as shown in Equation (1).

  Here, the DA converter 34 converts the digital data into an analog signal at a sampling rate sufficiently higher than the sampling rate of the AD converter 46. As a result, the DA converter 34 operates at a higher speed and has a wider operation band than the AD converter 46. Further, the output stage circuit of the DA converter 34 (for example, the transformer 344) also has a wide frequency characteristic. Therefore, the frequency characteristics of the DA converter 34 are close to ideal (gain 1, phase 0) in the operating band of the AD converter 46.

  When the frequency characteristic of the DA converter 34 is ideal, the S parameter of the path from the input end of the input circuit 44 to the output end of the AD converter 46 matches the S parameter of the 2-port network 70. Therefore, the calculation unit 58 calculates the S parameter of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46 by calculating the S parameter of the two-port network 70 expressed by the equation (1). can do.

In the two-port network 70, the output signal b ₁ from the input port 72 and the input signal a ₂ to the output port 74 are zero. Therefore, S ₁₁ , S ₁₂ and S ₂₂ in the formula (1) are 0. Then, _{S 21} in the formula (1) is expressed by the following equation (2).

Therefore, the calculation unit 58 can calculate the S parameter of the input circuit 44 and the AD conversion unit 46 by calculating the above equation (2) based on the input waveform data and the measured waveform data. In other words, the calculation unit 58 divides the waveform level represented by the measured waveform data by the waveform level represented by the input waveform data, so that the S parameter (coefficient S ₂₁₎ of the input circuit 44 and the AD conversion unit 46 is obtained. ) Can be calculated. In the present embodiment, the calculation unit 58 calculates an S parameter for each frequency. Then, the calculation unit 58 gives the S parameter for each frequency calculated during the characteristic measurement to the correction unit 48.

The correction unit 48 corrects the measurement waveform data output from the AD conversion unit 46 based on the given S parameter for each frequency during the test, and supplies the corrected measurement waveform data to the determination unit 16. More specifically, the correction unit 48 corrects the signal output from the AD conversion unit 46 based on the given S parameter (coefficient S ₂₁ ) for each frequency as represented by the following equation (3). To do. That is, the correction unit 48 decomposes the output waveform data for each frequency component, dividing each frequency component, the signal value B _ADC output from the AD conversion unit 46, the coefficient S ₂₁ of S parameters of the corresponding frequency To correct. In Equation (3), B _ADC (f) represents the frequency f component of the signal output from the AD converter 46, and B _O (f) represents the frequency f component of the corrected signal value. S ₂₁ (f) represents the frequency f component of the S parameter coefficient S ₂₁ .

FIG. 4 shows an example of the S parameter (coefficient S ₂₁ ) calculated by the calculation unit 58. The calculation unit 58 measures and stores the S parameter (coefficient S ₂₁ ) of the input circuit 44 and the AD conversion unit 46 for each frequency. Calculating section 58, as an example, a predetermined frequency band (e.g., 40MHz～80MHz) for each predetermined frequency in, by measuring the real and imaginary components of the coefficients _{S 21} of S parameters of the input circuit 44 and the AD converter 46, You may remember. Then, the calculation unit 58 gives the measured S parameter for each frequency of the input circuit 44 and the AD conversion unit 46 to the correction unit 48.

  FIG. 5 shows an example of frequency characteristics of a multitone signal generated as reference waveform data generated from the reference waveform generator 52. For example, the reference waveform generator 52 may generate reference waveform data obtained by digitizing a multitone signal. A multitone signal is a signal in which a plurality of frequency components are combined. As an example, the multitone signal may include a signal of a predetermined level for each predetermined frequency in a predetermined frequency band (for example, 40 MHz to 80 MHz).

  The switching control unit 54 provides the DA converter 34 with reference waveform data obtained by digitizing the multitone signal generated by the reference waveform generation unit 52 instead of the input waveform data at the time of characteristic measurement. The calculation unit 58 calculates transfer characteristics for each frequency of the input circuit 44 and the AD conversion unit 46. For example, the calculation unit 58 may decompose the measurement waveform data acquired by the acquisition unit 56 into frequency components by FFT calculation or the like, and calculate the S parameter for each frequency. Thereby, according to the signal input / output device 20, the transfer characteristics for each frequency of the input circuit 44 and the AD conversion unit 46 can be measured in a short time.

  Note that the reference waveform generation unit 52 may generate a multitone signal in which the level of each frequency component is adjusted so that the difference between the maximum value and the minimum value in the time domain becomes smaller. Thereby, according to the reference waveform generation unit 52, it is possible to reduce the distortion of the multitone signal generated in the transmission path from the DA conversion unit 34 to the AD conversion unit 46.

  Further, the reference waveform generation unit 52 may generate reference waveform data obtained by digitizing a multi-tone signal in which attenuation of a high frequency component due to 0th-order hold in the DA conversion unit 34 is corrected in advance. Thereby, according to the reference waveform generation unit 52, errors generated in the DA conversion unit 34 can be removed, and the transfer characteristics of the input circuit 44 and the AD conversion unit 46 can be calculated more accurately.

  FIG. 6 shows a configuration of a test apparatus 10 according to a first modification of the present embodiment. Since the test apparatus 10 according to this modification employs substantially the same configuration and function as the members having the same reference numerals shown in FIG. 1, the description thereof will be omitted except for the following differences.

  The input circuit 44 according to this modification can change the transfer characteristics. As an example, the input circuit 44 can switch coefficients and combinations of amplifiers, attenuators, filter circuits, and the like in the path, and the transfer characteristics can be changed by switching these coefficients. The switching control unit 54 according to this modification changes the transfer characteristic of the input circuit 44 according to the control of the user or the like.

  The acquisition unit 56 according to this modification acquires measurement waveform data for each path in the input circuit 44 at the time of characteristic measurement. The calculation unit 58 calculates the transfer characteristic of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46 for each path in the input circuit 44. The calculation unit 58 calculates the reverse characteristic of the transfer characteristic of the path from the input end of the input circuit 44 to the output end of the AD conversion unit 46 for each path in the input circuit 44, and sends the calculated reverse characteristic to the correction unit 48. give.

  Then, the correction unit 48 corrects the output waveform data for each path in the input circuit 44 according to the inverse characteristic of the transfer characteristic of the corresponding path during the test. Thereby, according to the correction | amendment part 48, even if it is a case where the transfer characteristic of the input circuit 44 can be changed, output waveform data can be correctly correct | amended corresponding to each path | route.

  Further, the test apparatus 10 according to this modification further includes an attenuation unit 80 and an amplitude control unit 82. The attenuator 80 attenuates the analog signal output from the DA converter 34. The attenuation unit 80 supplies the attenuated analog signal to the second switching unit 42. Then, the switching control unit 54 switches the second switching unit 42 so that the signal output from the attenuation unit 80 is supplied to the input circuit 44 instead of the analog signal from the device under test 300 during the characteristic measurement.

  The amplitude controller 82 controls the amplitude of the analog signal output from the DA converter 34 according to the amplification factor of the input circuit 44. In this example, the amplitude control unit 82 controls the amplitude of the analog signal output from the DA conversion unit 34 by controlling the attenuation rate by the attenuation unit 80.

  Here, the amplitude control unit 82 controls the attenuation rate of the attenuation unit 80 according to the amplification rate of the input circuit 44 so that the signal output from the input circuit 44 is included in the input voltage range of the AD conversion unit 46. . More specifically, the amplitude control unit 82 is configured so that the amplitude of the signal output from the input circuit 44 is at least larger than the resolution of the AD conversion unit 46 and equal to or less than the maximum input possible value of the AD conversion unit 46. Control the attenuation factor of 80. Thereby, according to the amplitude control part 82, even if it is a case where the gain of the input circuit 44 changes, the waveform can be digitized by the AD conversion part 46.

  FIG. 7 shows an example of the configuration of the input circuit 44 according to this modification. For example, the input circuit 44 may include a band limiting unit 92, an amplifying unit 94, a filter unit 96, and a path switching unit 98.

  The band limiting unit 92 outputs a signal obtained by band limiting the analog signal output by the second switching unit 42. The band limiting unit 92 includes a plurality of band limiting circuits 102, a first band limiting unit internal switch 104, and a second band limiting unit internal switch 106. The plurality of band limiting circuits 102 are circuits having different transfer characteristics. Each of the plurality of band limiting circuits 102 may have substantially the same circuit configuration as the band limiting circuit 60 shown in FIG. 2 as an example. The first band limiting unit switch 104 and the second band limiting unit switch 106 select any one of the plurality of band limiting circuits 102 according to the selection signal from the path switching unit 98 and select the selected band limiting circuit. The analog signal output by the second switching unit 42 is passed through 102.

  The amplification unit 94 includes a plurality of amplification circuits 112, a first amplification unit switch 114, and a second amplification unit switch 116. The plurality of amplifier circuits 112 are circuits having different amplification factors. The first amplifying unit switch 114 and the second amplifying unit switch 116 select one of the plurality of amplifying circuits 112 according to the selection signal from the path switching unit 98, and band-limit the selected amplifying circuit 112. The analog signal output by the unit 92 is passed.

  The filter unit 96 filters the analog signal output from the amplification unit 94 and outputs the filtered analog signal. The path switching unit 98 supplies a selection signal to the band limiting unit 92 and the amplifying unit 94 in accordance with the control from the switching control unit 54. According to the input circuit 44 as described above, paths having different transfer characteristics can be changed.

  Note that the test apparatus 10 described above may be a test circuit provided in the same electronic device together with a circuit under test to be tested. The test circuit is realized as a BIST circuit or the like of an electronic device, and diagnoses the electronic device by testing the circuit under test. Thus, the test circuit can check whether the circuit to be tested can perform the normal operation originally intended by the electronic device.

  The test apparatus 10 may be a test circuit provided on the same board or the same apparatus as the circuit under test to be tested. Such a test circuit can also check whether or not the circuit under test can perform the intended normal operation as described above.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

FIG. 1 shows a configuration of a test apparatus 10 according to an embodiment of the present invention, together with a device under test 300. FIG. 2 shows an example of the configuration of the output circuit 36 shown in FIG. FIG. 3 shows a two-port network 70 formed during characteristic measurement. FIG. 4 shows an example of the S parameter (coefficient S ₂₁ ) calculated by the calculation unit 58 according to the embodiment of the present invention. FIG. 5 shows an example of the frequency characteristic of the multitone signal generated as the reference waveform data generated from the reference waveform generator 52 according to the embodiment of the present invention. FIG. 6 shows a configuration of a test apparatus 10 according to a first modification of the embodiment of the present invention. FIG. 7 shows an example of the configuration of the input circuit 44 according to the first modification of the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Test apparatus 12 Waveform memory 14 Transfer part 16 Judgment part 20 Signal input / output device 26 Output terminal 28 Input terminal 32 1st switching part 34 DA conversion part 36 Output circuit 42 2nd switching part 44 Input circuit 46 AD conversion part 48 Correction | amendment part 52 Reference waveform generator 54 Switching controller 56 Acquisition unit 58 Calculation unit 60 Band limiting circuit 62 First attenuator 64 Filter circuit 66 Second attenuator 68 Amplifier 70 Two-port network 72 Input port 74 Output port 80 Attenuator 82 Amplitude controller 92 Band limiting unit 94 Amplifying unit 96 Filter unit 98 Path switching unit 102 Band limiting circuit 104 First band limiting unit switch 106 Second band limiting unit switch 112 Amplifying circuit 114 First amplifier unit switch 116 Second amplifier unit switch 300 Device under test 342 Differential DAC
344 Transformer 462 Differential amplifier 464 Differential ADC

Claims (8)

A signal input / output device for analog signals,
A DA converter that outputs an analog signal corresponding to given input waveform data;
An output circuit for transmitting an analog signal output by the DA converter to an output terminal;
An AD converter that outputs output waveform data according to a given analog signal;
An input circuit for transmitting an analog signal input via an input terminal to the AD converter;
At the time of characteristic measurement, a predetermined reference waveform data is given to the DA converter instead of the input waveform data, and a signal between the DA converter and the output circuit is substituted for an analog signal from the input terminal. A switching control unit for supplying to the input circuit,
An acquisition unit for acquiring the output waveform data output by the AD conversion unit as measurement waveform data at the time of the characteristic measurement;
A signal input / output device comprising: a calculation unit that calculates transfer characteristics of the input circuit and the AD conversion unit based on the reference waveform data and the measurement waveform data.   The signal input / output device according to claim 1, further comprising a correction unit that corrects the output waveform data according to a reverse characteristic of a transfer characteristic of the input circuit and the AD conversion unit. The switching control unit, instead of the input waveform data, gives reference waveform data obtained by digitizing a multitone signal to the DA conversion unit,
The signal input / output device according to claim 1, wherein the calculation unit calculates transfer characteristics for each frequency component of the input circuit and the AD conversion unit. The input circuit can change the transfer characteristics;
The signal input / output device according to claim 1, further comprising an amplitude control unit that controls an amplitude of an analog signal output from the DA conversion unit in accordance with an amplification factor of the input circuit. An attenuator for attenuating the analog signal output by the DA converter;
The signal input / output device according to claim 4, wherein the amplitude control unit controls an attenuation rate by the attenuation unit. The signal input / output device according to claim 1, wherein the DA conversion unit converts digital data into an analog signal at a sampling rate higher than a sampling rate of the AD conversion unit. A test apparatus for testing a device under test,
A DA converter that outputs an analog signal corresponding to input waveform data representing a waveform of a test signal to be supplied to the device under test;
An output circuit for transmitting the analog signal output by the DA converter to the device under test;
An AD converter that outputs output waveform data according to a given analog signal;
An input circuit for transmitting an analog signal output from the device under test to the AD converter;
A correction unit that corrects the output waveform data according to a reverse characteristic of a transfer characteristic of the input circuit and the AD conversion unit;
Based on the corrected output waveform data, a determination unit that determines pass / fail of the device under test,
At the time of characteristic measurement, a predetermined reference waveform data is given to the DA converter instead of the input waveform data, and an analog signal from the device under test is substituted between the DA converter and the output circuit. A switching control unit for supplying a signal to the input circuit;
An acquisition unit for acquiring the output waveform data output by the AD conversion unit as measurement waveform data at the time of the characteristic measurement;
A test apparatus comprising: a calculation unit that calculates transfer characteristics of the input circuit and the AD conversion unit based on the reference waveform data and the measurement waveform data. An electronic device,
The circuit under test;
A test circuit for testing the circuit under test,
The test circuit includes:
A DA converter that outputs an analog signal corresponding to input waveform data representing a waveform of a test signal to be supplied to the circuit under test;
An output circuit for transmitting the analog signal output by the DA converter to the circuit under test;
An AD converter that outputs output waveform data according to a given analog signal;
An input circuit for transmitting an analog signal output from the circuit under test to the AD converter;
A correction unit that corrects the output waveform data according to a reverse characteristic of a transfer characteristic of the input circuit and the AD conversion unit;
A determination unit for determining pass / fail of the circuit under test based on the corrected output waveform data;
At the time of characteristic measurement, predetermined reference waveform data is given to the DA converter instead of the input waveform data, and between the DA converter and the output circuit instead of the analog signal from the circuit under test. A switching control unit for supplying a signal to the input circuit;
An acquisition unit that acquires the output waveform data output by the AD conversion unit as measurement waveform data at the time of the characteristic measurement;
An electronic device comprising: a calculation unit that calculates transfer characteristics of the input circuit and the AD conversion unit based on the reference waveform data and the measurement waveform data.

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