JPS6158323A - Testing method of data converter - Google Patents

Abstract

PURPOSE:To highly accurately measure the characteristics of data converters, by adding a digital input signal to a DA converter and sending the output of the DA converter to an AD converter, and then, comparing the digital output signal of the AD converter with the digital input signal. CONSTITUTION:Characteristic tests are performed on the linearity, monotonous increase, offset, mis-code, etc., of an AD converter (ACD) 2 and DA converter (DAC) 3, by comparing a digital input voltage signal impressed upon the DAC 3 from a digital data generator 8 with a digital output voltage signal outputted from the DAC 2 and detected by a digital detector 9. Then the transmission loss, frequency characteristic, transmission loss level characteristic, signal-to- overall distortion power ratio characteristic, etc., of the ADC 2 and DAC 3 are found by the calculation of the digital signal, by controlling the digital generator 8 with a computer which is not shown in the figure, generating a digital AC and impressing the digital AC upon the DAC 3, digital-data detecting 9 the digital AC output voltage signal of the ACD 2, and then, digital-processing the output voltage signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a method for testing the characteristics of an analog-to-digital converter and a digital-to-analog converter in a device that includes both the converter as a component. Regarding.

[Conventional technology]

In recent digital equipment, for example, audio PCM system C
Analog-to-digital converter (hereinafter referred to as A) like 0DEC
DC) and digital-to-analog converter (hereinafter referred to as DA)
C) are often included together. In this case, the ADC and DAC often have non-linear conversion characteristics rather than linear conversion characteristics. In the case of the CODEC, the input/output characteristics of the built-in ADC and DAC are coarse at large amplitudes and relatively finely quantized at small amplitudes.

In C0DEC, the output digital signal of ADC, DAC
The input digital signal of is made up of 8 bits: code pit (1 pit) and data bits (7 bits).However, as mentioned above, the input/output characteristics of ADC and DAC are nonlinear. The finely quantized portion corresponds to 13 data bits when converted to an ADC or DAC with linear input/output characteristics.

Traditionally, AD built into equipment that includes both ADC and DAC
Also when testing C or DAC, the individual ADC, D
The input/output characteristics of AC were measured. That is, in the case of an ADC, the output from an analog voltage generator is led to the input side, the decile value on the output side is detected, and the input voltage is changed to obtain the output characteristics. In the case of DAC, this is done individually as well.

[Problem that the invention seeks to solve]

However, testing the low-level characteristics of nonlinear ADCs and DACs as described above requires extremely high-precision measuring instruments and measurement techniques at low levels, and is extremely difficult. Particularly, in analog measuring instruments such as analog voltage generators, oscillators, and voltmeters, the consistency requirement Z is severe.

Also ADC.

Since the measurement is carried out with the DAC built-in, it is necessary to extend the analog signal line to the measuring instrument, which has the disadvantage of being susceptible to noise.

The purpose of the present invention is to eliminate all the above-mentioned drawbacks and to
The object of the present invention is to provide an entire method that eliminates the 111 constant and tests the ADC and DACLv characteristics using only the (ljl constant) of a digital signal, allowing high accuracy and easy measurement.

[Means for solving problems]

In the test method according to the present invention, in order to test a digital-to-analog converter and an analog-to-digital converter included in a device, the analog-to-digital converter is cascade-connected to the digital-to-analog converter, and the・Input a digital human signal to the analog converter, extract the digital output signal sound of the analog-to-digital converter, and determine whether the digital-to-analog converter and the analog-to-digital converter are connected based on the relationship between the digital input signal and the digital output signal. All characteristics of the test are tested.

[f'11: Kan] In this test method, the analog signal that is the output of the digital-to-analog converter is immediately transferred manually to the digital-to-analog converter, and the wiring length for the analog signal in between can be extremely short, so noise is reduced. In addition, all analog-related oscillators, voltmeters, etc. are no longer required, and the characteristics of the data converter can be tested using only digital measurements.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a circuit block diagram for explaining the test method. ADC2 and DAC included in device 1! 1. As shown in the figure, the analog output terminal 7 of the DAC 5 is connected to the analog input terminal 4 of the ADC 2 with the shortest possible connection 10, making a cascade connection.

(-, apply the digital signal voltage of the digital data generator 8 from the digital input terminal 6 of the DAC 3, and
The output of the digital output terminal 5 of the DC 2 is inputted to the digital data detector 9.

In the above test circuit, first, ADC2 + DAC
◎Digital data generator 8, digital human power pressure multiplier applied to DAC3 and digital data output from ADC2 will be explained.
By comparing the digital output voltage signal detected by the f:I unit 9, it is possible to perform characteristic tests on linearity, monotonous increase, offset, miss code, etc. of the ADC 2 and DAC 3.

Next, in the alternating current characteristic test site @-, the digital data generator 8 is controlled by a computer (not shown) to generate a digital alternating current waveform, which is applied to the DAC 3 and
The digital AC output voltage signal sound of No. 2 is detected by the digital data detector 9, and the data is processed by the digital signal processing device @ (not shown).
AC transmission characteristics such as transmission loss frequency characteristics, transmission loss level characteristics, and signal to total power ratio characteristics described in No. 3 can be calculated only by calculating digital signals.

〔Effect of the invention〕

As explained in detail above, in the present invention, the ADC
and DACk Since the variation characteristics can be tested entirely by digital means under conditions close to the actual usage conditions, high TGI analog measuring instruments are no longer required. Also l
) A Connect analog output terminal 7 of C3 to A with short A connection 10
Since it is connected to analog input terminal 4 of DQ2 and measured, will analog noise be mixed in? Sup1flJ L,,8
511 feet are certainly easily performed. Therefore, it is particularly effective for inspection at the wafer stage when a half-cut integrated circuit is formed on one chip.

In the case of AC measurement, it is also possible to apply signal tones of a plurality of frequencies at once for measurement, and measurement can be carried out quickly.

This test method is particularly useful for converters with non-linear characteristics that have a low level of j:') and a small range of variation, as explained in the example, but it is not necessarily limited to this, and can also be used in the case of linear characteristics. Needless to say, it is applicable.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an embodiment of the present invention. 1... ADQ DAC Satoru 1 imager, 2... Analog-digital converter 3... Digital analog 4... Analog input terminal, converter (DAC), 5... Digital output terminal, 6...Digital input terminal, 7...Analog output terminal, 8...
Digital data generator, 9... Digital data detector, 10... Connection.

Claims (1)

[Claims] There is an analog-to-digital converter and a digital converter in the device.
As a test method for the converter when both analog converters are included as constituent elements, the analog-to-digital converter is connected in cascade to the digital-to-analog converter, and a digital input signal is input to the digital-to-analog converter. and extracting the digital output signal of the analog-to-digital converter, and testing the characteristics of the digital-to-analog converter and the analog-to-digital converter from the relationship between the digital input signal and the digital output signal. Test method for data converters.