Automatic test system and test method for analog-to-digital converter

Abstract

The invention discloses an automatic test system for an analog-to-digital converter. The automatic test system comprises an upper computer, a bus adapter, a test board card and an ADC to be tested. And the upper computer is used for setting working modes for the first DAC and the first ADC, setting a program control setting value of a reference voltage output by the first DAC, reading an actual output value of the reference voltage measured by the first ADC, and reading a digital code output by the ADC to be tested. And the bus adapter is used for communicating with the upper computer and the test board card. In the test board card, a first DAC is used for outputting a DC reference voltage as the input of an ADC to be tested; the first ADC is used for measuring the voltage value of the reference voltage output by the first DAC in real time; the resolution of the first ADC > the output resolution of the first DAC > the resolution of the ADC to be tested. And the to-be-tested ADC is used for taking the reference voltage output by the first DAC as input, performing analog-to-digital conversion on the reference voltage and then outputting a digital code. The device is high in testing precision, low in economic cost and good in universality.

Description

Technical Field

[0001] The present application relates to a testing technology for an analog-to-digital converter (ADC). Background Art

[0002] Analog-to-digital converters are widely used in communication, control and other fields. It is very important to accurately and quickly test the relevant technical indicators of analog-to-digital converters. Nowadays, with the continuous improvement of the sampling speed and accuracy of analog-to-digital converters, traditional testing technology can no longer meet current needs. Traditional analog-to-digital converter test instruments are expensive and costly; they are large in size and difficult to carry. Summary of the invention

[0003] The technical problem to be solved by the present application is: how to reduce the economic cost as much as possible while ensuring the test accuracy of the analog-to-digital converter, and how to reuse it in any analog-to-digital converter test scenario.

[0004] In order to solve the above technical problems, the present application proposes an automatic test system for an analog-to-digital converter, including a host computer, a bus adapter, a test board, and an ADC to be tested; the test board specifically includes a first DAC and a first ADC. The host computer is used to set the working mode for the first DAC and the first ADC, and is also used to set the program-controlled setting value of the reference voltage output by the first DAC, and is also used to read the actual output value of the reference voltage measured by the first ADC, and is also used to read the digital code output by the ADC to be tested. The bus adapter is used to communicate with the host computer and the test board. In the test board, the first DAC is used to output a DC reference voltage as the input of the ADC to be tested; the first ADC is used to measure the voltage value of the reference voltage output by the first DAC in real time; the resolution of the first ADC>the output resolution of the first DAC>the resolution of the ADC to be tested. The ADC to be tested is used to use the reference voltage output by the first DAC as input, and after analog-to-digital conversion, output a digital code.

[0005] Preferably, the host computer is developed using LabVIEW.

[0006] Exemplarily, the host computer reads the digital code output by the ADC to be tested through a UART interface.

[0007] Exemplarily, the bus adapter communicates with the host computer via a USB interface.

[0008] Exemplarily, the bus adapter communicates with the first DAC and the first ADC in the test board through an SPI communication bus.

[0009] Exemplarily, the first DAC outputs a reference voltage to the first ADC and the ADC to be tested simultaneously through analog output terminals AO and GND.

[0010] Furthermore, the operating mode of the first DAC refers to different output resolutions.

[0011] Furthermore, the working mode of the first ADC refers to different signal input methods and reading rates.

[0012] The present application also proposes an automatic test method for an analog-to-digital converter, comprising the following steps. Step S1: The host computer sets the working mode for the first DAC and the first ADC; the resolution of the first ADC> the output resolution of the first DAC> the resolution of the ADC to be tested. Step S2: The host computer provides the first DAC with a program-controlled setting value of the reference voltage, and the first DAC outputs a DC reference voltage according to the program-controlled setting value, and provides it to the ADC to be tested and the first ADC at the same time. Step S3: The first ADC collects the actual output value of the reference voltage in real time; the host computer reads the actual output value of the reference voltage measured by the first ADC, and records the program-controlled setting value and the actual output value of the reference voltage. Step S4: The ADC to be tested uses the reference voltage as input, performs analog-to-digital conversion on it, and outputs a digital code; the host computer reads and records the digital code output by the ADC to be tested. The order of the steps S3 and S4 can be either first or simultaneously. Step S5: The host computer changes the program-controlled setting value of the reference voltage, and repeats steps S2 to S4 until all program-controlled setting values ​​of the reference voltage have been tested. Step S6: The host computer analyzes the data recorded in each round of testing to obtain the integral nonlinearity INL characteristics and differential nonlinearity DNL characteristics of the ADC to be tested.

[0013] Preferably, in step S5, all programmed setting values ​​of the reference voltage form a ramp signal, that is, a rising ramp signal that increases according to a certain step length.

[0014] The technical effects achieved by this application are: high test accuracy, low economic cost and good versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the automatic test system of the analog-to-digital converter proposed in this application.

[0016] Figure 2 It is a flow chart of the automatic testing method of the analog-to-digital converter proposed in this application. DETAILED DESCRIPTION

[0017] See also Figure 1 The automatic test system of the analog-to-digital converter proposed in the present application includes: a host computer, a bus adapter, a test board, and an ADC to be tested. The test board is framed by a dotted line and specifically includes a first DAC (digital-to-analog converter) and a first ADC.

[0018] The host computer is used to set the working mode for the first DAC and the first ADC, and is also used to set the program-controlled setting value of the reference voltage output by the first DAC, and is also used to read the actual output value of the reference voltage measured by the first ADC, and is also used to read the digital code output by the ADC to be tested. The host computer is, for example, an industrial computer, a personal computer, etc., preferably developed using LabVIEW. LabVIEW is an automated test system development software with a graphical programming environment, which has the advantages of fast development speed and support for multi-threaded processing. As an example, the host computer reads the digital code output by the ADC to be tested through a UART interface (Universal Asynchronous Receiver / Transmitter) so as to perform related data analysis later.

[0019] The bus adapter is used to communicate with the host computer and the test board. As an example, the bus adapter communicates with the host computer via a USB interface, and the bus adapter communicates with the first DAC and the first ADC in the test board via an SPI (Serial Peripheral Interface) communication bus. The SPI bus has four signal lines, namely a clock line SCK, a master device input slave device output line MISO, a master device output slave device input line MOSI, and a chip select device selection line NSS.

[0020] In the test board, the first DAC is used to output a DC reference voltage as the input of the ADC to be tested. The first ADC is used to measure the voltage value of the reference voltage output by the first DAC in real time. As an example, the first DAC outputs a DC reference voltage to the first ADC and the ADC to be tested simultaneously through analog output terminals AO and GND. The program-controlled setting value of the reference voltage is controlled by the host computer, and the actual output value of the reference voltage is acquired by the first ADC, and the two are not completely equal. For example, the host computer sets the first DAC to output a reference voltage of 1V, and the reference voltage measured by the first ADC is 0.99231V.

[0021] The ADC to be tested is used to take the DC reference voltage output by the first DAC as input, perform analog-to-digital conversion on the DC reference voltage, and then output a digital code.

[0022] The working mode of the first DAC refers to different output resolutions (output accuracy). The host computer always sets the output resolution of the first DAC to be higher than the resolution of the ADC to be tested, so as to meet the accuracy requirements of the test. For example, the first DAC uses a 24-bit DAC chip. When the ADC to be tested is 12 bits, the host computer sets the output resolution of the first DAC to 16 bits. When the ADC to be tested is 16 bits, the host computer sets the output resolution of the first DAC to 20 bits.

[0023] The working mode of the first ADC refers to different signal input modes and reading rates. The host computer can set the first ADC to single-ended input or differential input, preferably differential input, to prevent interference from external common mode noise.

[0024] For example, the first ADC uses a 24-bit ADC chip. Preferably, the resolution of the first ADC is always higher than the output resolution set by the host computer for the first DAC, so as to meet the accuracy requirements of the test.

[0025] See also Figure 2 The automatic testing method of the analog-to-digital converter proposed in this application includes the following steps. Figure 2 The method shown uses Figure 1 System shown.

[0026] Step S1: The host computer sets the working mode for the first DAC and the first ADC. Specifically, the host computer sets the output resolution for the first DAC and sets the signal input mode and reading rate for the first ADC through the bus adapter. The resolution of the first ADC>the output resolution of the first DAC>the resolution of the ADC to be tested.

[0027] Step S2: the host computer provides a program-controlled setting value of a reference voltage to the first DAC through the bus adapter, and the first DAC outputs a DC reference voltage according to the program-controlled setting value, and provides it to the ADC to be tested and the first ADC at the same time.

[0028] Step S3: The first ADC collects the actual output value of the reference voltage in real time. The host computer reads the actual output value of the reference voltage measured by the first ADC, and records the program-controlled setting value and the actual output value of the reference voltage.

[0029] Step S4: The ADC to be tested uses the reference voltage as input, performs analog-to-digital conversion on it, and outputs a digital code. The host computer reads and records the digital code output by the ADC to be tested.

[0030] There is no strict restriction on the order of step S3 and step S4, and they can be performed either before or simultaneously.

[0031] Step S5: The host computer changes the program-controlled setting value of the reference voltage, and repeats steps S2 to S4 until all program-controlled setting values ​​of the reference voltage have been tested. For example, all program-controlled setting values ​​of the reference voltage form a ramp signal, that is, a rising ramp signal that increases in a certain step size. The first program-controlled setting value of the reference voltage is 0V, and then gradually increases in steps of 0.1V, and the cut-off voltage is 1.8V. The second program-controlled setting value of the reference voltage is 0.1V, the third program-controlled setting value of the reference voltage is 0.2V, ..., the nineteenth program-controlled setting value of the reference voltage is 1.8V, and after 19 rounds of testing, the test ends.

[0032] Step S6: The host computer analyzes the data recorded in each round of testing to obtain the INL (Integral NonLiner) characteristic and DNL (Differencial NonLiner) characteristic of the ADC to be tested.

[0033] The measurement of high-precision ADC has always been a difficult point in ADC testing. This application proposes a low-cost and high-precision ADC testing solution. In conjunction with the host computer, it can accurately obtain and record the program-controlled setting value and actual output value of the DC reference signal. The automatic test of the ADC is completed by generating a DC reference voltage that changes according to certain rules and cyclically reading the digital code of the ADC to be tested, which greatly improves the efficiency of ADC testing and avoids the inconsistency and incompleteness of manual testing.

[0034] Compared with the prior art, the present application has the following beneficial effects.

[0035] First, the reference voltage output by the first DAC with the second highest precision is read by the first ADC with the highest precision, and the ADC to be tested with the lowest precision is tested, thereby fully ensuring the test accuracy.

[0036] Second, the actual test process of the high-precision ADC will inevitably be disturbed by external environmental noise. The reference voltage output by the first DAC may be distorted by the external environment, and the digital code value of the ADC to be tested read by the host computer may also change. This application detects the relevant changes caused by external interference in real time by testing the first ADC with the highest accuracy built into the board, and can find and delete abnormal test results, so as to more accurately obtain the performance of the ADC to be tested.

[0037] Third, the present application is universal and can conveniently and automatically test different types of ADCs to be tested.

[0038] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should all be included in the protection scope of the present application.

Claims

1. An automatic test system for an analog-to-digital converter, characterized in that: It includes a host computer, a bus adapter, a test board, and an ADC to be tested; the test board specifically includes a first DAC and a first ADC; The host computer is used to set the working mode for the first DAC and the first ADC, to set the program-controlled setting value of the reference voltage output by the first DAC, to read the actual output value of the reference voltage measured by the first ADC, and to read the digital code output by the ADC to be tested; The bus adapter is used to communicate with the host computer and the test board; In the test board, the first DAC is used to output a DC reference voltage as an input of the ADC to be tested; The first ADC is used to measure the voltage value of the reference voltage output by the first DAC in real time; The resolution of the first ADC>the output resolution of the first DAC>the resolution of the ADC to be tested; The ADC to be tested is used to take the reference voltage output by the first DAC as input, perform analog-to-digital conversion on the reference voltage, and then output a digital code.

2. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The host computer is developed using LabVIEW.

3. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The host computer reads the digital code output by the ADC to be tested through the UART interface.

4. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The bus adapter communicates with the host computer via a USB interface.

5. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The bus adapter communicates with the first DAC and the first ADC in the test board through the SPI communication bus.

6. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The first DAC outputs a reference voltage to the first ADC and the ADC to be tested simultaneously through analog output terminals AO and GND.

7. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The operating mode of the first DAC refers to different output resolutions.

8. The automatic test system for analog-to-digital converter according to claim 1, characterized in that: The working mode of the first ADC refers to different signal input methods and reading rates.

9. An automatic testing method for an analog-to-digital converter, characterized in that: The method comprises the following steps: Step S1: The host computer sets the working mode for the first DAC and the first ADC; the resolution of the first ADC>the output resolution of the first DAC>the resolution of the ADC to be tested; Step S2: the host computer provides a program-controlled setting value of a reference voltage for the first DAC, and the first DAC outputs a DC reference voltage according to the program-controlled setting value, and provides the DC reference voltage to the ADC to be tested and the first ADC at the same time; Step S3: the first ADC collects the actual output value of the reference voltage in real time; The host computer reads the actual output value of the reference voltage measured by the first ADC, and records the program-controlled setting value and the actual output value of the reference voltage; Step S4: The ADC to be tested uses the reference voltage as input, performs analog-to-digital conversion on it, and outputs a digital code; The host computer reads and records the digital code output by the ADC to be tested; The order of step S3 and step S4 may be either first or second, or they may be performed simultaneously; Step S5: the host computer changes the program-controlled setting value of the reference voltage, and repeats steps S2 to S4 until all program-controlled setting values ​​of the reference voltage have been tested; Step S6: The host computer analyzes the data recorded in each round of testing to obtain the integral nonlinearity INL characteristics and differential nonlinearity DNL characteristics of the ADC to be tested.

10. The automatic testing method of the analog-to-digital converter according to claim 9, characterized in that: In step S5, all programmed setting values ​​of the reference voltage form a ramp signal, that is, a rising ramp signal that increases according to a certain step length.

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