JPS5863229A - Testing device for analog-digital converter - Google Patents

Abstract

PURPOSE:To perform a test for numbers of items in a short time, by obtaining with high accuracy the threshold value to the digital output code of an A/D converter and storing the data of obtained threshold value. CONSTITUTION:An A/D converter C to be tested receives the digital signal of a counter A which counts the clocks and digitizes the analog output signal given from a D/A converter B having a larger number of bits than the converter C. This digital signal is fed to a comparator E directly or via a temporary storage circuit D. The comparator E delivers an output every time the output code of the converter C varies. The output codes of both the counter A and the converter C of that moment are stored in the storage circuits M1 and M2. Thus the circuit M1 stores with high accuracy the threshold value to the changing point of the converter C. A processor CPU reads and processes the codes stored in the circuits M1 and M2. In such a way, the various functions of the converter C can be tested with high accuracy and at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a testing device for analog-to-digital converters.

Conventional, analog and digital converters (hereinafter referred to as Φ converters)
Due to the nature of the errors, it is difficult to use a common tester to measure errors (linearity errors, bits and toes, gain errors, etc.) in the measurement items. This was done using a dedicated testing device.

In addition, the measurement method is to input a certain value as an analog input and compare the digital output with the standard value to perform all tests qualitatively, and quantitatively compare data such as accelerated tests. That was difficult. In addition, when measuring with a general-purpose tester at a low analog input level of the A/D converter, it takes time to set the level and to make a judgment after conversion, resulting in a very long measurement time. became.

SUMMARY OF THE INVENTION An object of the present invention is to provide a testing device for analog-to-digital converters that overcomes these conventional drawbacks.

A feature of the present invention is that a test device for testing an analog-to-digital converter includes a digital signal generation section that generates an arbitrary digital signal, an analog signal generation section that outputs an analog signal corresponding to the digital signal, and a A detection section that detects a change point in the digital output signal of the measurement analog-to-digital converter, a storage section that stores the digital signal and the digital output signal based on the detection signal of this detection section, and a storage section that depends on the contents of this storage section. The present invention provides an analog-to-digital converter testing device including a determining section for determining the acceptability of the analog-to-digital converter under test. for example,
The output of the counting circuit is converted to a digital-to-analog converter (hereinafter referred to as D).
/A converter. ) digital input and storage circuit M
The analog output of the D/A converter is connected to the input of the D/A converter under test (hereinafter referred to as A/D
Abbreviated as converter. ), the output of the A/D converter is input to the memory circuit M2, and the A/D converter output is input to the memory circuit M2;
The digital output of the D converter is connected to the input of a temporary storage circuit for storage in a digital manner and one input of the comparison circuit, and the output of the temporary storage circuit is connected to the other input of the comparison circuit. However, due to the configuration of the temporary storage circuit and the comparison circuit, the means for detecting a change in the digital output code of the sand exchanger changes when the values of the two manual forces of the comparison circuit are different. The outputs are sent to the memory circuits Ml and M
! is connected to the write input of the memory circuit and the clock input of the temporary memory circuit, the outputs of the memory circuits Ml and M2 are connected to the processing circuit input, and the temporary memory circuit and the comparator circuit:
Detecting a change in the digital output code of the A/D converter, storing the output of the counting circuit and the digital output code of the A/D converter, and processing the outputs of the storage circuits M1 and M2 in a processing circuit. Things to do - Features of analog
This is a test device for digital converters.

According to the present invention, the above-mentioned conventional drawbacks can be overcome by determining the threshold value for the digital output code of the A/D converter with high precision and storing the data.

An embodiment of the present invention will be described below with reference to the drawings.

The configuration of an embodiment of the present invention is shown in FIG. 1. From FIG. /Af converter B analog output DAoutT
The analog signal source for the A/D converter C is input DI2 and the input DI2 of the A/D converter quantity ADouTt storage circuit M2.
The output LAout of the temporary storage circuit is connected to the input LAIN of a temporary storage circuit for temporarily storing the digital output code of the D-conversion converter and one input CMB IN of the comparison circuit E. Other input CMA I
N [The configuration of the temporary memory circuit and the comparator circuit E detects changes in the digital output code of the A/DKA device C, and outputs the output that changes when the values of the two manual CMAIN and CMBIN of the comparator circuit E are different. CMOUTt'Memory circuit Ml
and the write inputs MWIN1 and MW□N2 of M2 and the clock input CLIN of the temporary storage circuit, and the outputs of the storage circuits R41 and M2, respectively. □Andri. 2 is connected to the processing circuit CPU, and the temporary storage circuit and comparison circuit E detect changes in the A/D converter digital output code, and the output code CoUT of the counting circuit A and the digital output code of the A/D converter are detected. memory circuits Ml and M2
The feature is that the processing circuit CPU processes the output.

Next, the operating principle will be explained. D/A converter quantity digital manual DAINK with bit number larger than A/D converter quantity bit count: Connect output Cout' of counting circuit A from which all digital codes of D/A converter B can be obtained. . Then, the D/A converter analog output DAout
Let it be the signal source of the analog input ADIN of converter C.

Further, the counting circuit A counts up by +1 according to the clock input from the clock input CIN. Let us start from the starting state. As an initial condition, the output Cout of the counting circuit A is set to 0 code, the D/A converter quantity output DAOUT is also set to OV, the output ADOUT of the A/D converter C is also set to 0 code, and the contents of the temporary storage circuit are also set to 0 code. Furthermore, memory circuits M1 and M2
Both addresses are also 0 code.

Now, clock CIN of counting circuit N is clocked manually.

When the value is input, the count circuit input/output C0UT is counted up. That is, the D/4 conversion converter power DAOut
The analog level is rising.

However, since the A/D converter power ADOUT does not change unless the threshold voltage for changing the code from O to 1 is input, no change occurs in the other circuits. Next, as shown in Figure 2, when the pulse from At is input, the A/D conversion converter power ADOUT changes from O to 1 code. output co
This is the threshold level where u'r changes from O to 1.

Output ADOU? becomes a code of 1, and the input CMB of comparator circuit E! N, and the output LAOU of the temporary storage circuit
When compared with t, since the input values are different, the output CMOU'r of the comparison circuit E changes. Then, this change causes the write inputs #lNl and rJF MW of the memory circuits M'l and M2.
The contents of the output Cout of the counting circuit input to IN2 are written to the memory circuit Ml, and the output A of the A/D converter C is
The contents of Dout (code of 1) will be written to the t-memory circuit M2. Further, the output CMooT of the comparator circuit E is input to the clock input CL and N of the temporary memory circuit, and the temporary memory circuit D [is the content 1 of the A/D converter output ADOUT.
The code will be memorized. Then, the input CM&IN of the comparison circuit E receives a code of 1, and the input CMBIN becomes 1.
Since this is the code, CMOUT returns to its original state. At this time, the address of memory circuits M1 and M2 is t+1. Now A
/D conversion The processing when the converter power AD, ui changes is shown. By repeating this operation, all the A/D converter power ADQυT codes are stored in the memory circuit M2, and the threshold values for each code are also stored in the memory circuit M1.

Further, the threshold level is determined as follows. Now, if the full-scale voltage of D/A converter B is tvytrLv, then D
The voltage per bit of D/A converter B is
A bit of. Assuming a number iN bits (where N is an integer), Vν
It becomes υLL/2NV. Therefore, as shown in the previous example, A
The threshold value at which the /D conversion converter power ADOU'r changes from O to 1 code is (counting circuit A with clock A1. Therefore, increasing the value of N will increase the accuracy. , the relationships between the addresses and data of the memory circuits M1 and M2 are not limited to those described above.

For example, among the measurement items, there is an item that requires linearity error. This is the change in input voltage when the output code of the A/D converter changes from one code to the next. positive integer) in this example ADD
It can be determined from the data value of M-ADDM-.

Also, there is a measurement item called "to-missing". Koreba A/
Generally, codes are generated in increments of +1 for the analog input of the D converter, but in some cases, a code that should be present may not exist due to a defect. This detection can also be discovered by sequentially reading out the contents of the memory circuit M2.

In the test IT configured according to the present invention, since the threshold values for all codes of the A/D converter are known, the processing by the processing circuit eliminates the need for test equipment for each measurement item as in the past. Also, in accelerated tests, etc., since the code and threshold value are known, it is possible to compare the data before and after the test, making it possible to adequately evaluate fluctuations. Furthermore, for data processing, the contents of the memory circuits M1 and A12 can be read out as needed after A/D conversion and necessary processing can be performed, and by using a high-speed processing circuit, the A/D converter code It is also possible to perform processing from one change point to the next change point, and this method can shorten the measurement time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the clock pulse of the counting circuit and the output code of the ~Φ converter. In the figure, A... Counting circuit % CIN... Black,
input terminal, cott'r...output of counting circuit, B...D/A converter, DA! N...
Digital input terminal, DAOUT """ Analog output terminal, C... Test A/D converter, ADIN...
...Analog input terminal% ADOUT...
Digital output terminal, I)...Temporary memory circuit, LA! N...Input terminal% L&□ UT・
...output terminal, CL■N...black input terminal, E...comparison circuit, CMA! N CMB
IN...Input terminal %CMOUT...Output terminal, Ml, M2...Memory circuit% DII, DI
2...Input terminal% DOI. ])02...Output terminal, MW! N1. MW! N2
．． , , , - write input terminal, CPU , , , , ,
, processing circuit, CPU■NI CPUxN2...
Input terminal' AI, A2... Black, number of inputs,
ADOUT: Output code of the A/D converter. (

Claims (1)

[Claims] A test device that tests analog-to-digital converters includes a digital signal generation section that generates an arbitrary digital signal, an analog signal generation section that outputs an analog signal corresponding to the digital signal, and a digital signal generation section that outputs an analog signal corresponding to the digital signal. a detection unit that detects a change point of an output signal; a storage unit that stores the digital signal and the digital output signal according to the detection signal of the detection unit; and a storage unit that stores the digital signal and the digital output signal depending on the contents of the storage unit. A tester for an analog-to-digital converter, characterized in that it includes a determination section for determining the quality of the converter.