JPH08335877A - Circuit device incorporating digital-analog conversion part - Google Patents

Abstract

PURPOSE: To surely perform the crosstalk test of plural D/A conversion parts without requiring preparation of a test data generation part on the outside with respect to the circuit device incorporating plural D/A conversion parts. CONSTITUTION: Plural D/A conversion parts 56, 64, and 65 including the D/A conversion part for D/A conversion of output data obtained from multiplication parts 58 and 60 which use the digital data from a sine wave data ROM 62 and a cosine wave data ROM 63 to process the digital color difference signal data, an all high data supply part 71 which supplies specific digital data for test to one of D/A conversion parts 56, 64, and 65 at the time of the crosstalk test of D/A conversion parts 56, 64, and 65, and a sine wave signal data supply part 72 which reads out digital sine wave signal data from the sine wave data ROM 62 to supply it to another of D/A conversion parts 56, 64, and 65 as data for test are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital-to-analog converter (D) for performing digital-to-analog conversion (D / A conversion) on digital information data to obtain an analog information signal.
D / A that has a plurality of built-in A / A converters and can perform a crosstalk test on those D / A converters.
The present invention relates to a conversion unit built-in circuit device.

[0002]

2. Description of the Related Art In a circuit device provided with a plurality of D / A converters, each of which performs D / A conversion on digital information data to obtain an analog information signal, a plurality of D / A converters are provided. The degree of crosstalk related to the converter is considered a problem. The crosstalk relating to the plurality of D / A converters here means an undesired influence of the data processed in each D / A converter on other D / A converters.

As a circuit device provided with a plurality of D / A converters, for example, digital luminance signal data and digital carrier color signal are obtained by digitally processing the digital primary color signal data which constitutes the digital video signal data. And a digital image signal for forming an analog luminance signal and an analog carrier color signal by subjecting the digital brightness signal data and the digital carrier color signal data to D / A conversion by respective D / A converters. An example is a signal encoder device. In a circuit device provided with a plurality of D / A converters such as such a digital video signal encoder device, when the degree of crosstalk regarding the plurality of D / A converters is relatively large, However, there is a possibility that an appropriate analog output, for example, an analog luminance signal or an analog carrier color signal, may not be obtained from the affected D / A converter.

Therefore, it has been proposed that the above-mentioned digital video signal encoder device or the like be subjected to a crosstalk test for measuring the crosstalk regarding a plurality of D / A converters. The crosstalk test for the plurality of D / A converters is performed by, for example, a specific test in which one of the plurality of D / A converters corresponds to a certain analog signal level. For supplying digital data for use and also for multiple D / A
The digital sine wave signal data corresponding to the analog sine wave signal is supplied to the other one of the conversion units, and the D / A conversion unit from one D / A conversion unit to which the specific test digital data is supplied. The signal level of the analog output is detected, and the degree of crosstalk received by one D / A conversion unit to which specific test digital data is supplied is determined from the detection result. In such a case, one D / A to which specific test digital data is supplied
The degree of crosstalk received by the conversion unit appears as a fluctuation in the signal level of the analog output from the D / A conversion unit.

FIG. 2 shows an example of a conventional digital video signal encoder device capable of performing a crosstalk test on a plurality of D / A conversion units incorporated therein. The conventional digital video signal encoder device 10 shown in FIG. 2 has external input terminals 11, 12, 13, 1.
A data selection / matrix unit 17 having 4, 15 and 16 is provided.

Digital video signal encoder device 10
However, under the original operating condition (normal operating condition), the data selection / matrix unit 17 outputs the digital red signal which is the digital primary color signal data from the outside through the external input terminals 11, 12 and 13. Data D
R, digital green signal data DG and digital blue signal data DB are respectively supplied. Then, from the data selection / matrix unit 17, digital luminance signal data DY and digital red color difference signal data D formed based on the digital red signal data DR, the digital green signal data DG and the digital blue signal data DB.
(RY) and digital blue color difference signal data D (B-
Y) is obtained.

The digital luminance signal data DY is subjected to a delay process for a predetermined time in the delay unit 18, and D / A
It is supplied to the conversion unit 19. Further, the digital red color difference signal data D (RY) is supplied to the multiplication unit 21 through a low pass filter (LPF) 20 having a pass band characteristic corresponding to the frequency band, and further, the digital blue color difference signal. The data D (BY) is supplied to the multiplication unit 23 through the LPF 22 having a pass band characteristic corresponding to the frequency band.

The multiplication units 21 and 23 are supplied with the modulation axis data DRR for the digital red color difference signal and the modulation axis data DRB for the digital blue color difference signal sent from the modulation axis data forming unit 24, respectively. Modulation axis data forming unit 24
Is a sine wave data read only memory (sine wave data ROM) 25 in which digital sine wave signal data DSIN corresponding to the analog sine wave signal is stored, and digital cosine wave signal data DCO corresponding to the analog cosine wave signal.
The cosine wave data read-only memory (cosine wave data ROM) 26 storing S stores the read control signals RS and RC.
Are appropriately supplied to read and capture the digital sine wave signal data DSIN from the sine wave data ROM 25, and read and capture the digital cosine wave signal data DCOS from the cosine wave data ROM 26. And
The modulation axis data forming unit 24 has the same frequency and a phase difference of 90 degrees based on the digital sine wave signal data DSIN and the digital cosine wave signal data DCOS fetched from the sine wave data ROM 25 and the cosine wave data ROM 26, respectively. Digital red color difference signal modulation axis data DRR and digital blue color difference signal modulation axis data DRB corresponding to the analog red color difference signal modulation axis signal and the analog blue color difference signal modulation axis signal, which are a pair of analog modulation axis signals. Is sent.

Modulation axis data D for digital red color difference signal
In the multiplication section 21 to which RR is supplied, the digital red color difference signal data D (RY) from the LPF 20 and the digital red color difference signal modulation axis data DRR are multiplied to obtain the digital carrier red color difference signal. The data DRC is obtained, and the modulation axis data D for the digital blue color difference signal is obtained.
In the multiplication unit 23 to which RB is supplied, the digital blue color difference signal data D (BY) from the LPF 22 and the modulation axis data DRB for the digital blue color difference signal are multiplied to obtain the digital carrier blue color difference signal. The data DBC is obtained. Then, the digital carrier red color difference signal data DRC from the multiplication unit 21 reaches the D / A conversion unit 27, and the digital carrier blue color difference signal data DB from the multiplication unit 23.
C is supplied to the D / A converter 28, respectively.

The D / A converter 19 performs D / A conversion on the digital luminance signal data DY,
An analog luminance signal Y is obtained, and the analog luminance signal Y is obtained.
Is led to the output terminal 30. In addition, the D / A converter 27
, The digital carrier red color difference signal data DRC
Is carried out to obtain an analog carrier red color difference signal C (RY), and the analog carrier red color difference signal C (RY) is led to the output terminal 31. Further, in the D / A conversion unit 28, D / A conversion is performed on the digital carrier blue color difference signal data DBC to obtain the analog carrier blue color difference signal C (BY).
The analog carrier blue color difference signal C (BY) is output to the output terminal 32.

Under these circumstances, the D / A converters 19 and 2 are
Crosstalk on 7 and 28 may occur,
At that time, for example, from the mutual arrangement relationship in the D / A conversion units 19, 27 and 28, for example, the D / A conversion units 19, 27 and 2
It is assumed that the D / A converter 27 of 8 has the greatest influence of the crosstalk from the other D / A converters.

A plurality of D / A converters built in the digital video signal encoder device 10, that is, D / A
When the crosstalk test is performed on the conversion units 19, 27 and 28, the data selection / matrix unit 1
7, the test digital data DS from the test data generator 33 through the external input terminal 14, the test digital data DH from the test data generator 34 through the external input terminal 15, and the external input terminal 16
The test digital data DS from the test data generator 35 is supplied through the respective.

The test digital data DS from each of the test data generator 33 and the test data generator 35 is digital sine wave signal data corresponding to the analog sine wave signal, and the test data generator 34.
The test digital data DH from 1 to 3 is set to correspond to a constant analog signal level, for example, "1".
It is considered as digital all-high data having a plurality of bits consisting of only bits representing

The data selection / matrix unit 17 receives the test digital data DS from the external input terminal 14 and the test digital data DH from the external input terminal 15.
When the test digital data DS is supplied from the external input terminal 16, the external input terminal 1
A data selection operation is performed in which the test digital data DS from the test data 4, the test digital data DH from the external input terminal 15, and the test digital data DS from the external input terminal 16 are sent as they are.

Test digital data DS, DH and DS sent from the data selection / matrix unit 17
Through terminals 37, 38 and 39 derived from the input ends of the D / A converters 19, 27 and 28, respectively,
It is supplied to the D / A converters 19, 27 and 28. As a result, in each of the D / A converters 19 and 28, the D / A conversion is performed on the test digital data DS that is the digital sine wave signal data, and the analog sine wave signal S is obtained. The analog sine wave signal S is output to the output terminals 30 and 32. Further, the D / A conversion unit 27 performs D / A conversion on the test digital data DH that has been converted into digital all-high data to obtain an analog output signal H having a level that should be constant. Output signal H is output terminal 31
Be derived to.

Under these circumstances, the D / A converters 19 and 28 are used.
In the D / A converter 27 that is affected by the crosstalk from each of the above, the analog output signal H having a level that should be constant is affected by the crosstalk from each of the D / A converters 19 and 28. It is considered that the level fluctuation according to is caused. Such level fluctuations in the analog output signal H from the D / A conversion unit 27 are subjected to a crosstalk test on the D / A conversion units 19, 27 and 28 as indicated by the chain line in FIG. At this time, it is detected by the level detection / determination unit 40 connected to the output terminal 31.

In the level detecting / determining section 40, D /
In the analog output signal H from the A conversion unit 27, D /
A level change corresponding to the influence of crosstalk from each of the A conversion units 19 and 28 is detected, and based on the detection result, the D / A conversion units 19 and 28 of the D / A conversion units 27 are affected. The degree of crosstalk from each is determined. Then, the output signal S representing the result of the determination about the degree of crosstalk from the level detection / determination unit 40.
CT is sent out.

[0018]

As described above, a plurality of built-in D / A conversion units, that is, D / A conversion units 1 are provided.
In the conventional digital video signal encoder device 10 in which the crosstalk test for 9, 27 and 28 is performed, for the crosstalk test, the test digital data which is the digital sine wave signal data is supplied to the outside thereof. It is necessary to provide two test data generating sections and a test data generating section that supplies specific test digital data that is, for example, digital all-high data. As described above, it is necessary to provide a plurality of types of test data generators outside the digital video signal encoder device 10.
The cost related to the execution of the crosstalk test in the digital video signal encoder device 10 increases, and the digital video signal encoder device 10
Therefore, work for connecting a plurality of types of test data generators is required.

In view of the above point, the present invention has a plurality of D / A conversion units which are provided with a plurality of D / A conversion units for performing D / A conversion on digital information data to obtain analog information signals. To provide a circuit device with a built-in D / A conversion unit, which can surely perform a crosstalk test for a unit without requiring a test data generation unit to be provided outside. To aim.

[0020]

In order to achieve the above-mentioned object, a circuit device with a built-in D / A converter according to the present invention is a sine wave data storing digital sine wave signal data corresponding to an analog sine wave signal. A memory section, an information signal data processing section for processing digital information signal data using the digital sine wave signal data read from the sine wave data memory section, and D for digital output data obtained from the information signal data processing section. A plurality of D / A including a D / A conversion unit that performs A / A conversion to obtain an analog information signal
When a test is performed on the A conversion unit and the plurality of D / A conversion units, a data supply unit that supplies specific test digital data to one of the plurality of D / A conversion units, and a plurality of D units. When a test is performed on the A / A conversion unit, digital sine wave signal data is read from the sine wave data memory unit and supplied as test data to each of the plurality of D / A conversion units other than the above-mentioned one. And a sine wave signal data supply unit.

[0021]

In the D / A converter built-in circuit device according to the present invention as described above, a state in which a crosstalk test is performed on a plurality of built-in D / A converters is taken.
When a crosstalk test is performed on a plurality of D / A conversion units, the data supply unit, for example, has a digital all-bit structure having a plurality of bits, each of which has only a bit representing "1" corresponding to a constant analog signal level. While supplying specific test digital data, which is high data, to one of the plurality of D / A conversion units,
The sine wave signal data supply unit reads the digital sine wave signal data from the sine wave data memory unit and uses the digital sine wave signal data for testing to each of the plurality of D / A conversion units other than the above-mentioned one. Supply as data.

As a result, the result of the crosstalk test for the plurality of D / A conversion units can be obtained based on the analog output obtained from one D / A conversion unit to which specific test digital data is supplied. The crosstalk test for the plurality of D / A converters is as follows.
This is done reliably without the need for an external test data generator.

[0023]

1 shows an example of a circuit device with a built-in D / A converter according to the present invention. In this example, digital primary color signal data constituting digital video signal data is digitally processed to obtain a digital luminance. The signal data and the digital carrier color signal data are formed, and the digital luminance signal data and the digital carrier color signal data are subjected to D / A conversion by the respective D / A converters to obtain an analog luminance signal and an analog carrier color. It forms a digital video signal encoder device for obtaining a signal.

In the example shown in FIG. 1, a matrix section 54 having external input terminals 51, 52 and 53 is provided. When the example shown in FIG. 1 is placed in its original operating state (normal operating state), the matrix section 54 has external input terminals 51, 52 and 53.
Through the outside, digital red color signal data DR, digital green color signal data DG, and digital blue color signal data DB, which are digital primary color signal data, are supplied from the outside. Then, from the matrix section 54, the digital luminance signal data DY, the digital red color difference signal data D (RY) and the digital blue signal data DY which are formed based on the digital red signal data DR, the digital green signal data DG and the digital blue signal data DB. Color difference signal data D (BY) is obtained.

The digital luminance signal data DY is subjected to a delay process for a predetermined time in the delay unit 55, and the D / A
It is supplied to the conversion unit 56. Further, the digital red color difference signal data D (RY) is supplied to the multiplication unit 58 through the LPF 57 having the pass band characteristic corresponding to the frequency band, and the digital blue color difference signal data D is further supplied.
(BY) is supplied to the multiplication unit 60 through the LPF 59 having a pass band characteristic corresponding to the frequency band.

The multiplication units 58 and 60 are supplied with the digital red color difference signal modulation axis data DRR and the digital blue color difference signal modulation axis data DRB sent from the modulation axis data forming unit 61, respectively. Modulation axis data forming unit 61
Is a sine wave data ROM 62 in which digital sine wave signal data DSIN corresponding to an analog sine wave signal is stored.
And a cosine wave data ROM 63 storing digital cosine wave signal data DCOS corresponding to the analog cosine wave signal.
In addition, the read control signals RS and RC are appropriately supplied to read the digital sine wave signal data DSIN from the sine wave data ROM 62 and load it, and read the digital cosine wave signal data DCOS from the cosine wave data ROM 63 to load it. Then, the modulation axis data forming unit 61
Is a sine wave data ROM 62 and a cosine wave data ROM 6
Digital sine wave signal data DS acquired from 3 respectively
An analog red color difference signal modulation axis signal and an analog blue color difference signal modulation axis which are a pair of analog modulation axis signals having the same frequency and different phases by 90 degrees based on IN and digital cosine wave signal data DCOS. Modulation axis data D for digital red color difference signal corresponding to each signal
Modulation axis data DRB for RR and digital blue color difference signal
Is sent.

Modulation axis data D for digital red color difference signal
In the multiplication unit 58 to which the RR is supplied, the multiplication process of the digital red color difference signal data D (RY) from the LPF 57 and the digital red color difference signal modulation axis data DRR is performed, and the digital carrier red color difference is obtained. Signal data DRC
In addition, in the multiplication unit 60 to which the digital blue color difference signal modulation axis data DRB is supplied, the LPF5
The digital carrier blue color difference signal data D (B-Y) from 9 is multiplied by the digital blue color difference signal modulation axis data DRB.
BC is obtained. Then, the digital carrier red color difference signal data DRC from the multiplication unit 58 is supplied to the D / A conversion unit 64.
The digital carrier blue color difference signal data DBC from the multiplication unit 60 is supplied to the D / A conversion unit 65. That is, the multiplication units 58 and 60 and the modulation axis data forming unit 6
1 is the digital sine wave signal data DSIN and the cosine wave data ROM 6 read from the sine wave data ROM 62.
Digital cosine wave signal data DCOS read from 3
Using the digital red color difference signal data D (RY)
And an information signal data processing section for processing the digital blue color difference signal data D (BY).

The D / A converter 56 performs D / A conversion on the digital luminance signal data DY,
An analog luminance signal Y is obtained, and the analog luminance signal Y is obtained.
Are led to the output terminal 66. In addition, the D / A converter 64
, The digital carrier red color difference signal data DRC
Is carried out to obtain an analog carrier red color difference signal C (RY), and the analog carrier red color difference signal C (RY) is led to the output terminal 67. Further, in the D / A converter 65, D / A conversion is performed on the digital carrier blue color difference signal data DBC to obtain an analog carrier blue color difference signal C (BY).
The analog carrier blue color difference signal C (BY) is output to the output terminal 68.

Under these circumstances, the D / A converters 56, 6
Crosstalk for 4 and 65 may occur,
At that time, for example, from the mutual arrangement relationship in the D / A conversion units 56, 64 and 65, for example, the D / A conversion units 56, 64 and 6
It is assumed that the D / A conversion unit 64 of 5 has the greatest influence of the crosstalk from the other D / A conversion units.

A plurality of D / A converters built in the example shown in FIG. 1, that is, D / A converters 56, 64 and 6 are provided.
When the crosstalk test for 5 is performed,
The crosstalk test command data DCT is sent to the test bus 7
0 to the all-high data supply section 71 and the sine-wave signal data supply section 72, and the all-high data supply section 71 and the sine-wave signal data supply section 72 are put into operation.

The all-high data supply section 71 in the operating state outputs digital all-high data of a plurality of bits composed of only bits representing "1", which correspond to a constant analog signal level. , Test digital data DH, and supplies the test digital data DH to the D / A converter 64 through a terminal 73 derived from the input terminal of the D / A converter 64. Further, the sine wave signal data supply unit 72 placed in the operating state stores the read control signal R in the sine wave data ROM 62.
N is supplied, and the digital sine wave signal data DSIN corresponding to the analog sine wave signal stored in the sine wave data ROM 62 is read, and the read digital sine wave signal data DSIN is used as test digital data. It is sent as DS, and the test digital data DS is sent to D / A converters 56 and 65 through terminals 74 and 75 respectively derived from the input terminals of D / A converters 56 and 65.
It is supplied to each of the / A conversion units 56 and 65.

As a result, in each of the D / A converters 56 and 65, D / A conversion is performed on the test digital data DS that has been converted into digital sine wave signal data, and an analog sine wave signal S is obtained. And the analog sine wave signal S is led to the output terminals 66 and 68.
Further, in the D / A conversion section 64, D / A conversion is performed on the test digital data DH that has been converted into digital all-high data, and an analog output signal H having a level that should be constant is obtained. The analog output signal H is led to the output terminal 67.

Under these circumstances, the D / A converters 56 and 65 are provided.
In the D / A conversion unit 64 that is affected by the crosstalk from the D / A conversion units 56 and 65, the analog output signal H having a level that should be constant is affected by the crosstalk from the D / A conversion units 56 and 65. It is considered that the level fluctuation according to is caused. Such level fluctuations in the analog output signal H from the D / A conversion unit 64 are subjected to a crosstalk test on the D / A conversion units 56, 64 and 65 as indicated by the chain line in FIG. At this time, it is detected by the level detection / determination unit 80 connected to the output terminal 67.

In the level detection / determination unit 80, D /
In the analog output signal H from the A converter 64, D /
A level change corresponding to the influence of crosstalk from each of the A conversion units 56 and 65 is detected, and based on the detection result, the D / A conversion units 56 and 65 of the D / A conversion units 64 are affected. The degree of crosstalk from each is determined. Then, the output signal S representing the result of the determination about the degree of crosstalk from the level detection / determination unit 80.
CT is sent out.

In this way, the crosstalk test for the D / A converters 56, 64 and 65 incorporated in the example shown in FIG. 1 is performed without the need for an external test data generator. The test digital data DH, which is digital all-high data from the all-high data supply unit 71, and the test digital data DS, which is digital sine-wave signal data from the sine wave signal data supply unit 72, are used to reliably perform the operation. Be seen.

In the example shown in FIG. 1 above, D /
The test digital data DH is supplied to the A conversion unit 64, and the test digital data DS is supplied to the D / A conversion units 56 and 65 to actually determine the degree of crosstalk. Is the D / A conversion unit 64, the test digital data DH is supplied to the D / A conversion unit 56 or 65, and the D / A conversion units 64 and 65 or the D / A conversion units 56 and 64. It is also possible to supply the test digital data DS to and determine the degree of crosstalk in the D / A converter 56 or 65.

Further, although the example shown in FIG. 1 is supposed to form a digital video signal encoder device,
The circuit device with a built-in D / A converter according to the present invention is not limited to such an example, and various digital information data can be obtained by using digital sine wave signal data from a sine wave data memory unit such as a sine wave data ROM. It is possible to incorporate a plurality of D / A converters that perform digital processing and perform D / A conversion on the processed digital information data to obtain analog information signals.

[0038]

As apparent from the above description, in the D / A converter built-in circuit device according to the present invention, when a crosstalk test is performed on a plurality of built-in D / A converters, The built-in data supply unit converts specific test digital data into a plurality of D digital data, which are digital all-high data having a plurality of bits including only bits representing “1” corresponding to a constant analog signal level. The digital sine wave signal data is supplied to one of the A / A conversion sections, and the built-in sine wave signal data supply section reads the digital sine wave signal data from the sine wave data memory section and outputs the digital sine wave signal data to a plurality of D / A converter sections. It is supplied as test data to each of the A conversion units other than the above-mentioned one, so that the crosstalk test for the plurality of D / A conversion units is performed. The result of is obtained based on the analog output obtained from one D / A converter to which specific test digital data is supplied. Therefore, a crosstalk test for a plurality of D / A converters is performed. This can be performed reliably without requiring the test data generator to be provided externally. Also, as a result,
The cost related to the execution of the crosstalk test will be reduced, and the work for connecting the test data generating section arranged outside will not be required.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a D / A converter built-in circuit device according to the present invention.

FIG. 2 is a block configuration diagram showing an example of a conventional digital video signal encoder device and a test data generating unit arranged outside thereof.

[Explanation of symbols]

 51, 52, 53 External input terminal 54 Matrix section 55 Delay section 56, 64, 65 D / A conversion section 57, 59 LPF 58, 60 Multiplying section 61 Modulation axis data forming section 62 Sine wave data ROM 63 Cosine wave data ROM 66 , 67, 68 Output terminal 70 Test bus 71 All-high data supply unit 72 Sine wave signal data supply unit 80 Level detection / determination unit

Claims (4)

[Claims] 1. A digital sine wave data memory unit storing digital sine wave signal data corresponding to an analog sine wave signal, and digital information signal data using the digital sine wave signal data read from the sine wave data memory unit. A plurality of digital-analog conversions including an information signal data processing unit for performing the processing of 1. and a digital-analog conversion unit for performing digital-analog conversion on digital output data obtained from the information signal data processing unit to obtain an analog information signal. Section, a data supply section that supplies specific test digital data to one of the plurality of digital-analog conversion sections when a test is performed on the plurality of digital-analog conversion sections, and the plurality of digital supply sections. -When testing the analog converter, The digital sine wave signal data is read from the sine wave data memory unit, and a sine wave signal data supply unit is supplied as test data to each of the plurality of digital-analog conversion units other than the above one. A circuit device with a built-in digital-analog converter. 2. A data supply section supplies, to one of the plurality of digital-analog conversion sections, digital data corresponding to a constant analog signal level as specific test digital data. The circuit device with a built-in digital-analog converter according to claim 1. 3. A modulation axis data forming section for forming a digital modulation axis data based on the digital sine wave signal data read from the sine wave data memory section by the information signal data processing section, the digital modulation axis data and the digital information signal. 2. The circuit device with a built-in digital-analog conversion unit according to claim 1, further comprising a multiplication unit that multiplies with data to obtain digital carrier information signal data. 4. The digital information signal data is digital color difference signal data corresponding to the analog color difference signal,
Digital carrier color signal data is obtained from the information signal data processing unit, and the digital carrier color signal data and the digital luminance signal data corresponding to the analog luminance signal are respectively supplied to a plurality of digital-analog conversion units. 4. The circuit device with a built-in digital-analog converter according to claim 3.