JP3144363B2 - Test circuit and test method for A / D / D / A converter with integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an integrated circuit type A
The present invention relates to a test circuit and a test method for a / D / D / A converter.

[0002]

2. Description of the Related Art A conventional A / D / D / A converter testing apparatus,
FIGS. 5, 6, and 7 are shown to explain the A / D / D / A converter test method. In these figures, the conventional A
A / D / D / A converter test apparatus and an A / D / D / A converter test method will be described. In these drawings, the same functions are denoted by the same reference numerals.

[0005] In the conventional example 1 shown in FIG.
The / A converter testing apparatus 10 includes an A / D converter 3, a D / A converter 4, a processing circuit 7, and a switch 13, and has input terminals 1, output terminals 2, and A / D converter output terminals. 8, D /
It comprises an A converter input terminal 9.

When a processing circuit 7 that does not test the A / D converter 3 and the D / A converter 4 is used, a switch 13 selects an output of the processing circuit 7. At the time of testing the A / D converter 3, analog test data is applied to the input terminal 1, and it is determined whether the digital data output from the A / D converter output terminal 8 has a prescribed value. Also, the D / A converter 4
At the time of the test, the specified data is applied to the D / A converter input terminal 9 and the analog output data of the D / A converter 4 output from the output terminal 2 is observed. I do. In this case, the A / D converter output terminal 8 and the D / A converter input terminal 9 need the number of output bits of the A / D converter 3 and the number of input bits of the D / A converter 4 respectively. Become.

Next, in the conventional example 2 shown in FIG. 6, the A / D converter output terminal 8 and the D / A converter input terminal 9 of the conventional example 1 shown in FIG. It is integrated as the D / A converter input terminal 11, and the test method is the same as that of the conventional example 1. The I / O switch 12 is used to switch the input / output function of the A / D converter output and D / A converter input terminal 11 between the A / D converter 3 test and the D / A converter 4 test. Prepare. In this case, the number of terminals of the A / D converter output / D / A converter input terminal 11 is determined by the number of output bits of the A / D converter 3 and the number of D / A converters.
The number of input bits of the / A converter 4 is the larger one.

The prior art 3 shown in FIG. 7 includes a switching circuit 13 for directly inputting the output of the A / D converter 3 to the D / A converter 4, and the output digital signal of the A / D converter 3 is provided. In this method, data is directly used as digital input data of the D / A converter 4. The analog test data is applied to the input terminal 1, the analog data output from the output terminal 2 is observed, and it is determined whether the analog data has a prescribed value. In this case, the combined characteristics of the A / D converter 3 and the D / A converter 4 are measured.

[0007]

However, each of the above-described conventional examples has the following problems. In the following:
The case where the number of output bits of the A / D converter 3 is 8 bits and the number of input bits of the D / A converter 4 is 10 bits will be described.

In the conventional example 1 shown in FIG. 5, as described above, the A / D converter output terminal 8 and the D / A converter input terminal 9 require a total of 18 terminals. Moreover, this terminal is used only when the A / D converter 3 and the D / A converter 4 are tested, and is not normally used.
The A / D / D / A converter test apparatus 10 is connected to an A / D / D / A
When applied to a semiconductor device with a built-in converter test device, an increase in the number of terminals leads to an increase in the package area as well as an increase in the number of members used. Therefore, there is a problem that the cost is increased at the time of mounting.

In the conventional example 2 shown in FIG. 6, an A / D converter output terminal 8 and a D / A converter input terminal 9 are integrated with the conventional example 1 shown in FIG. Converter output and D / A
The converter input terminal 11 is used. In the conventional example 2, the number of necessary terminals is ten, and the conventional example 1 shown in FIG.
The number of terminals required for testing the A / D converter 3 and the D / A converter 4 is about half that of However, there is still a problem that terminals that are not used except during the test remain, which increases the cost.

In the conventional example 3 shown in FIG. 7, the overall characteristics of the A / D converter 3 and the D / A converter 4 are measured, and the A / D converter output terminals 8 and D There is an advantage that the A / D converter output terminal 9 and the A / D converter output / D / A converter input terminal 11 in the conventional example 2 can be eliminated. However, for example, when the number of bits of the D / A converter 4 is larger than the number of bits of the A / D converter 3, there is a problem that the D / A converter 4 cannot be tested. As in the above example, the number of bits of the A / D converter 3 is 8 bits, and the number of bits of the D / A converter is 10 bi.
In the case of t, the upper 2 bits or lower 2 bits of the D / A converter 4 cannot be measured due to the difference in the number of bits between the two. As an even greater problem, the A / D converter 3, D /
The individual characteristics of the A-converter 4 cannot be tested. Further, if the common code of the A / D converter 3 and the D / A converter 4 has a defect such as loss, there is a problem that it cannot be detected.

As described above, in each of the above conventional examples, A
In order to individually measure the characteristics of the / D converter and the D / A converter, the cost increases due to an increase in the number of terminals. In the method of measuring the combined characteristics of the A / D converter and the D / A converter in order to reduce the number of terminals, when the number of bits of the A / D converter and the number of bits of the D / A converter are not the same, Cannot measure the characteristics of the entire range of the A / D converter or the D / A converter having the larger number of bits. Further, there is a problem that individual characteristics of the A / D converter and the D / A converter cannot be measured at all.

According to the present invention, the number of test terminals is reduced, and A /
An object of the present invention is to provide a test circuit and a test method for an A / D / D / A converter with a built-in integrated circuit, which enable testing of characteristics of each of a D converter and a D / A converter.

[0013]

Means for Solving the Problems] To solve the above problems
The invention according to claim 1 includes an A / D converter and a serial
/ Parallel converter or parallel / serial converter,
A switch, a D / A converter, and a predetermined
And a processing circuit.
A / D converter, serial / parallel converter between input / output terminals
Converter or parallel / serial converter, switcher, D / A
If the converters are serial and the serial / parallel converter or
Indicates that the output of the parallel / serial converter is
Input terminal and the input of the D / A converter are
Connected and the processing circuit is a serial / parallel converter or
The output terminal is in parallel with the parallel / serial converter.
Connected to the other selection terminal of the switch, the input terminal of the integrated circuit
The D / A converter or the A / D converter
Analog data as test data is input, and D / A
When testing the converter, use a serial / parallel converter.
Is analog data based on the output from the A / D converter.
The voltage range within which the
By obtaining digital data corresponding to the judgment multiple times,
Output to the D / A converter as real data, and perform A / D conversion
When testing the equipment, the parallel / serial converter
The output bit of the A / D converter is divided, and the divided bit
The number of input bits of the D / A converter
Generate a code with the number of bits and divide it multiple times
Output to the D / A converter and output from the D / A converter
Observe the analog data and observe the characteristics of the D / A converter or
The characteristics of the A / D converter are measured.

[0014] The invention according to claim 2 is the invention according to claim 1.
Of A / D / D / A converter with built-in integrated circuit
The test circuit is a serial / parallel converter or a parallel /
A storage device is provided before or after the serial converter.
Real / parallel converter or parallel / serial converter
Device and storage device are configured in parallel with the processing circuit,
When testing the D / A converter, the device
The parallel data output from the rel converter is stored.
Output from the A / D converter when testing the A / D converter
Characterized by storing parallel data.

According to a third aspect of the present invention, there is provided an A / D converter,
Serial / parallel converter or parallel / serial converter
Converter, switcher, D / A converter, and
Integrated circuit type A / D
In the D / A converter test method, an A / D converter and a serial
Real / parallel converter or parallel / serial converter
, Switch, and D / A converter are connected in series
A switching step for switching the connection of the switching device as described above,
D / A converter or A / D converter at the input terminal of the integrated circuit
Input analog data as test data to be tested
Input process and analog data output from D / A converter
Measuring the D / A converter.
When the A / D conversion is performed by a serial / parallel converter
The analog data is output in any voltage range based on the output from the
Is determined to be within the box, and the data corresponding to the determination is determined.
By acquiring digital data multiple times, it becomes parallel data
When outputting to the D / A converter and testing the A / D converter,
Is a parallel / serial converter, and the output of the A / D converter is
Divides the input bit, and according to the content of the divided bit.
Has the same number of bits as the number of input bits of the D / A converter
Generates a code, divides it a plurality of times, and
Output, the measuring step, D / A converter characteristics or A
The characteristics of the / D converter are measured.

The invention according to claim 4 is the invention according to claim 3.
, Serial / parallel converter or parallel
/ A storage device is arranged before or after the serial converter,
Serial / parallel converter or parallel / serial converter
A converter and a storage device are configured in parallel with the processing circuit,
When testing a D / A converter, the serial / parallel conversion
A / D converter stores parallel data output from the converter.
When testing the converter, the output from the A / D converter
Characterized by having a storage step of storing the parallel data
I do.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a test circuit and a test method for an A / D / D / A converter with a built-in integrated circuit according to the present invention. Referring to FIGS. 1 to 4, the integrated circuit built-in type A / D.D / A of the present invention will be described.
One embodiment of a converter test circuit and test method is shown.

FIG. 1 shows a configuration in a case where a D / A converter is tested in the first embodiment of the present invention. In FIG. 1, an A / D / D / A converter test apparatus 10 includes an A / D converter 3, a D / A converter 4, a serial / parallel converter 5,
A normal processing circuit 7 and a switch 13 are built in. A /
In the D / D / A converter test apparatus 10, the setting of the switch 13 at the time of the test uses data from the serial / parallel converter 5 as an input to the D / A converter 4.

The signal generator 21 outputs, as digital analog data, serial data obtained by converting parallel data necessary for testing the D / A converter 4 to an input terminal 1.
Give to. Here, digital analog data is data that can be easily determined as digital data after the given data is converted by the A / D converter 3. For example, the digital data “0” and “1” are respectively set below the lower limit of the input range, which is outside the conversion range of the A / D converter 3, and above the upper limit of the input range.

When this data is given to terminal 1, A / D
The conversion outputs of the converter 3 are all "0" and all "1", that is, the minimum value and the maximum value of the conversion range, and this data is converted into "0" and "1" in the serial / parallel converter 5, respectively. Is set to be determined. D /
Since the input data of the A converter 4 is in a parallel format, the serial / parallel converter 5 receives all the serial data necessary for forming the parallel format data and forms the parallel data. Output to

The D / A converter 4 performs D / A conversion on the parallel-converted data, and outputs the analog data after the D / A conversion to the output terminal 2. The output data is measured by the voltmeter 22 and it is determined whether or not the output data matches the specified voltage, and the D / A converter 4 is tested. The above is only the test of the output of the D / A converter 4 for one specific code.
Therefore, the above process is executed for the number of codes required to test the characteristics of the D / A converter 4 over the entire range. By using the above configuration and method, D
It is not necessary to provide a dedicated data input terminal for testing the / A converter 4.

FIG. 2 shows a configuration in a case where an A / D converter is tested in the second embodiment of the present invention. 2, an A / D / D / A converter test apparatus 10 includes an A / D converter 3, a D / A converter 4, a parallel / serial converter 6, a normal processing circuit 7, and a switching unit 13. are doing. A / D
In the D / A converter test apparatus 10, the A / D converter 3
At the time of the test, the setting of the switch 13 is set so that the data from the parallel / serial converter 6 is input to the D / A converter 4.

The signal generator 21 outputs analog data necessary for testing the A / D converter 3 and supplies the analog data to the input terminal 1. The A / D converter 3 A / D converts the given analog data and inputs the analog data to the parallel / serial converter 6 as parallel data. The input parallel data is
In the parallel / serial converter 6, the D / A converter 4
Is converted into data which becomes serial digital analog data at the output of and output.

Here, the digital analog data is data in which analog data can be easily determined as digital data. For example, digital data “0” and “1” are all set to “0” and all “1” with respect to the number of input bits of the D / A converter 4.

D which receives this digital analog data
The / A converter 4 outputs the minimum value or the maximum value of the output amplitude to the output terminal 2. The voltage at the output terminal 2 is measured by the voltmeter 22, and the midpoint potential of the output of the D / A converter 4 is set as a threshold, and a higher voltage is determined as “1” and a lower voltage as “0”. Thus, one bit of the digital data is recognized. This process is repeated for the number of output bits of the A / D converter 3 to convert the serial data received by the voltage measuring device 21 into parallel data. Thereby, the A / D converter 3
Can be obtained, and the A / D converter 3 is tested by comparing the output code with the expected value code.

The above is the description of the A / D converter 3 for a specific voltage.
This process is executed for the number of voltages necessary to test the A / D converter 3 because the test is only for the output of the A / D converter. By using the above configuration and method, it is not necessary to provide a dedicated data output terminal for testing the A / D converter 3. Note that a general converter is sufficient for the serial-parallel conversion and the parallel-serial conversion.

Next, as an example of a test system of the D / A converter in the third embodiment, FIG. 3 shows a configuration in which a storage device is added to the configuration of the first embodiment shown in FIG. In FIG. 3, the A / D / D / A converter test apparatus 10 includes an A / D converter 3, a D / A converter 4, a serial / parallel converter 5, a normal processing circuit 7, a storage device 14, and a switch. The container 13 is built in. In the A / D / D / A converter test apparatus 10, when the D / A converter is tested, the setting of the switch 13 is set so that data from the storage device 14 is input to the D / A converter 4. . The setting method and processing method from the signal generator 21 to the A / D converter 3 and the serial / parallel converter 5 are the same as in the first embodiment.

In FIG. 3, after the parallel data from the serial / parallel converter 5 is stored in the storage device 14 as necessary, the stored data is given to the D / A converter 3 to be tested. In the first embodiment, in order to configure one data to be given to the D / A converter 3, the number of A / Ds equal to the number of bits of the D / A converter 4 is set.
The data must be converted by the converter 3. During this conversion, the next data cannot be provided. For this reason,
Although there is no problem in the low-speed test of the D / A converter 4, measurement with continuous data cannot be performed. By using this method, a test in which parallel data is continuously given to the D / A converter 4 becomes possible.

FIG. 4 shows an example of a test method of the A / D converter according to the fourth embodiment in which a storage device is added to the configuration of the second embodiment shown in FIG. In FIG. 4, A / D · D
The / A converter test apparatus 10 includes an A / D converter 3, a D / A converter 4, a parallel / serial converter 6, a normal processing circuit 7, a storage device 14, and a switch 13.

In the A / D / D / A converter test apparatus 10, when the A / D converter 3 is tested, the switch 13 is used to transmit data from the parallel / serial converter 6 to the D / A converter 4.
Set as input. When the A / D converter 3 is tested, the parallel data output from the A / D converter 3 is temporarily stored in the storage device 14, the stored data is sequentially read out, and the serial data is converted by the parallel / serial converter 6 into serial data.
/ A converter 4. In the configuration of the second embodiment, the next input data cannot be processed until the parallel / serial converter 6 finishes converting the parallel output data from the A / D converter 2. However, by using this method, it is possible to test continuous data of the A / D converter 3 within the range of the storage capacity of the storage device 14.

The following are examples of the storage device described above. 2. Description of the Related Art In a device incorporating an A / D converter and a D / A converter, in order to obtain output data by comparing past data with present data in a process of processing data, the device stores the past data. In some cases, a storage device is built-in.

For example, in the case of separating composite image data into luminance data and color data, in the case of a method of separating using the phase between lines, a line memory for storing data for one horizontal period is incorporated. In the case of the separation method using the correlation between frames, a frame memory is incorporated. An A / D converter, a D / A
It is used as a temporary storage device for parallel data used for testing when testing the converter. As a result, it is possible to realize this without having a dedicated storage device.

Further, in the first embodiment and the second embodiment, the digital analog data is Hi / Lo 1
The case of bit has been described. However, the A / D converter 3, D /
The input data to the A / D converter of the first embodiment and the D / A converter 4 of the second embodiment are within a range in which the accuracy of the A converter 4, the signal generator 21, and the voltage measuring device 22 is sufficient. By setting the input data gray scale to 2 bits or more, the number of times input data is given and the number of times output data is measured can be reduced. This enables high-speed processing.

In the third and fourth embodiments, when the data transfer rate inside the device is high and it is difficult to input data from outside, output data to outside, or measure the data, However, the test can be stably performed. In the case of a D / A converter, data is input at a low speed and stored in a storage device, and then read out at a high speed and applied to the D / A converter.
This is because, in the case of a D converter, data can be input / output at a low speed by storing the A / D converted high-speed data once in a storage device and then reading the data at a low speed.

In the test apparatus for the A / D, D / A, and converter of the above embodiment, when testing the D / A converter, serial digital analog data is input to the A / D converter.
After serial-to-digital conversion in the apparatus, the signal is supplied to a D / A converter, and the analog output of the D / A converter is measured. In the test of the A / D converter, the output data of the A / D converter is converted into parallel / serial data and then supplied to the D / A converter as analog digital data, and the output of the D / A converter is output as a digital output. Is determined.

The above embodiment is an example of a preferred embodiment of the present invention. However, it is not limited to this.
Various modifications can be made without departing from the spirit of the present invention.

[0037]

As is apparent from the above description, the test circuit and the test method for the A / D / D / A converter with a built-in integrated circuit according to the present invention are suitable for testing a D / A converter. By serially / parallel-converting the data from the A / D converter and supplying the data to the D / A converter, the data from the A / D converter is converted into parallel / serial when the A / D converter is tested. Give to D / A converter. This makes it possible to test the D / A converter and the A / D converter alone without providing a data input terminal for the D / A converter test and a data output terminal for the A / D converter test. Becomes possible. For this reason, in the case of a semiconductor device, a reduction in the number of terminals enables a reduction in the chip area and a reduction in the package size, and thus a reduction in cost. Further, by temporarily storing the parallel data in the storage device in the apparatus, it is possible to perform a test in an actual operation state regardless of the conversion speed of serial / parallel conversion or parallel / serial conversion.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a test circuit and a test method of an A / D / D / A converter with a built-in integrated circuit of the present invention.

FIG. 2 is a block diagram showing a second embodiment.

FIG. 3 is a block diagram showing a third embodiment.

FIG. 4 is a block diagram showing a fourth embodiment.

FIG. 5 is a block diagram of a first conventional example.

FIG. 6 is a block diagram of a second conventional example.

FIG. 7 is a block diagram of a third conventional example.

[Explanation of symbols]

 Reference Signs List 1 input terminal 2 output terminal 3 A / D converter 4 D / A converter 5 serial / parallel converter 6 parallel / serial converter 7 processing circuit 8 A / D converter output terminal 9 D / A converter input terminal 10 A / D / D / A converter testing device 11 A / D converter output and D / A converter input terminal 12 I / O switch 13 Switch 14 Storage device 21 Signal generator 22 Voltage measuring device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI G08C 13/00

Claims (4)

(57) [Claims] An A / D converter, a serial / parallel converter or a parallel / serial converter, a switch,
An A / A converter, a predetermined processing circuit normally used,
An A / D converter, the serial / parallel converter or the parallel / serial converter, the switching device, the D / A conversion between input / output terminals of the integrated circuit. Vessels in series,
And an output of the serial / parallel converter or the parallel / serial converter is connected to one selection terminal of the switch and an input of the D / A converter is connected to a common terminal of the switch. The serial / parallel converter or the parallel / serial converter is connected in parallel with an output terminal connected to the other selection terminal of the switch. The input terminal of the integrated circuit includes the D / A converter or Analog data is input as test data for testing the A / D converter. When the D / A converter is tested, the serial / parallel converter outputs the data from the A / D converter. Then, it is determined in which voltage range the analog data is within, and by obtaining digital data corresponding to the determination a plurality of times, the D / D When outputting to the A / D converter, and testing the A / D converter, the parallel / serial converter divides the output bit of the A / D converter, and according to the divided bit content, A code having the same number of bits as the number of input bits of the D / A converter is generated, divided into a plurality of times, and output to the D / A converter. Analog data output from the D / A converter Measuring the characteristics of the D / A converter or the characteristics of the A / D converter by observing the A / D converter.
Test circuit for D / A converter. 2. A test circuit for the A / D / D / A converter with a built-in integrated circuit, comprising: a storage device at a stage before or after the serial / parallel converter or the parallel / serial converter; A parallel / parallel converter or the parallel / serial converter and the storage device are configured in parallel connection with the processing circuit, and the storage device is configured to test the D / A converter from the serial / parallel converter. 2. The integrated circuit built-in type according to claim 1, wherein parallel data output from the A / D converter is stored when testing the A / D converter. A
Test circuit for / D / D / A converter. 3. An A / D converter, a serial / parallel converter or a parallel / serial converter, a switch,
An A / A converter, a predetermined processing circuit normally used,
A method for testing an A / D / D / A converter with a built-in integrated circuit, comprising: the A / D converter; the serial / parallel converter or the parallel / serial converter;
A switching step of switching connection of the switch so that the D / A converter is connected in series; and a test for testing the D / A converter or the A / D converter at an input terminal of the integrated circuit. An input step of inputting analog data as data; and a measuring step of measuring analog data output from the D / A converter. When testing the D / A converter, the serial / A parallel converter determines, based on an output from the A / D converter, a voltage range within which the analog data falls, and obtains digital data corresponding to the determination a plurality of times to obtain parallel data. When the output to the D / A converter is performed and the A / D converter is tested, the output bit of the A / D converter is divided by the parallel / serial converter. A code having the same number of bits as the number of input bits of the D / A converter is generated in accordance with the content, the code is divided a plurality of times and output to the D / A converter. A method for testing an A / D / D / A converter with a built-in integrated circuit, wherein the characteristics of the A / D converter or the characteristics of the A / D converter are measured. 4. A storage device is provided before or after said serial / parallel converter or said parallel / serial converter, and said serial / parallel converter or said parallel / serial converter and said storage device are said processing circuits. When the D / A converter is tested, the parallel data output from the serial / parallel converter is stored. When the A / D converter is tested, the D / A converter is tested. 4. The method for testing an A / D / D / A converter with a built-in integrated circuit according to claim 3, further comprising a storage step of storing parallel data output from the A / D converter.