JPS59132226A - Automatic measuring system of analog-digital converter characteristic - Google Patents

Abstract

PURPOSE:To attain automatic measurement at a high speed by using a general- purpose computer for a control section, stepping up an analog voltage optionally to simplify the constitution and to set optionally the step-up width. CONSTITUTION:A standard voltage generator 10 inputs an analog voltage 101 increased/decreased in an optional step to an A/D converter 13 by a control signal 300 from the general-purpose computer 20. An output code 102 A/D-converted is outputted to the general-purpose computer 20 as data. Further, the general- purpose computer 20 monitors always an output code 102 and detects an unstable change in the converted output code. The analog voltage value and the converted output code are transmitted to a display device 12 as display data 104. When the display is finished, a display end signal 105 is transmitted to the general-purpose computer 20 to change the setting of the analog voltage output of the standard voltage generator 10. All codes of the A/D converter 13 and the analog voltage are measured and recorded by the cyclic operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for automatically measuring the characteristics of an A/D (analog/digital) converter in a short period of time. As shown in the figure.

In FIG. 1, an output signal 100 of a counter 200 from a control unit 11 causes a standard voltage generator 1o to generate an analog voltage 101 that increases in steps necessary for measurement accuracy.
input to the converter 13. A/D converted output code 1
02 (MSB-1, 8B) is output to the control unit 11 as data. In addition, the control unit 11 is 103 (L8B)
changes in the conversion output sign are constantly monitored to detect unstable changes in the converted output sign. When the A/D conversion output code 102 changes from the unstable region to the stable region, the counter 200 in the control section 11 is stopped by the signal 103.

The analog voltage holds the value at that time. Control circuit 2
02 sends the output analog voltage 107 of the generator 1o as display data to the display device 12 for display. When the display of the analog voltage is completed, the counter 200 is started by the display end signal 105, and the analog voltage is stepped with the precision required for measurement. During this time, the control circuit 202
A signal 109 to latch the converted output code 102 to the register 201 is sent. When the output code 1.02 reaches the turning point from the stable region to the unstable region, the control section 11 stops the counter 200* and displays the analog voltage at that time. In response to the analog voltage display end signal at this time, the A/D conversion output code latched in the register 201 is displayed on the display device 12 via the control circuit 202. These-
By repeating the cycle, all the codes and analog voltages of the A/D converter are measured and recorded.

In the case of this method, the control unit 11 is constructed of hardware and is complicated. The step-up of the analog voltage is constant, and the steps need to be small to increase accuracy. Therefore, there is a drawback that the time required for step-up is wasted in areas other than the transition point between the stable region and the unstable region.

In order to solve these drawbacks, the present invention provides a control unit 11
This method uses a general-purpose computer for the system, and can be configured more easily than conventional systems. Another feature is that the analog voltage can be stepped up arbitrarily.

The drawings will be explained in detail below.

FIG. 2 is a block diagram of an embodiment according to the invention. In FIG. 2, a standard voltage generator 1o inputs an analog voltage 101 that increases or decreases in arbitrary steps to an A/D converter 13 in accordance with a control signal 300 from a general-purpose computer (eg, a microcomputer) 20. The A/D converted output code 102 (MSB-L8B) is output as data to the general-purpose computer 2°. Still, general purpose computer 20 constantly monitors output code 102 to detect unstable transitions in the converted output code. The analog voltage value and the converted output code are sent to display device #12 as display data 104. When the display is completed, a character end signal 105 is sent to the general purpose computer 2° to change the setting of the analog voltage output of the standard voltage generator. Through these cyclic operations, the entire sign and analog voltage of the A/D converter are measured and recorded. In addition, the measured conversion output sign and analog voltage are stored in the external storage device 21 as stored data 301.
is memorized.

Next, as an example, a data measurement operation of an 8-bit A/D converter with a bit width of approximately 10 mV will be described. General purpose computer 2
An analog voltage (■ in FIG. 3) that increases in large steps by a control signal 300 from 0 is input to the A/D converter. A/D converter output code 102 by a general-purpose computer
is constantly monitored, and when it is confirmed that the unstable region has changed to the stable region, the analog voltage decreases by one step (Fig. 3 ■). Next, increase the analog voltage in small steps and measure the transition point between the unstable region and the stable region (Figure 3 ■). The data at this turning point is stored in the internal storage device or external storage device of the general-purpose computer 20 (FIG. 3). In the same way, the point of change from the stable region to the unstable region is measured and stored (Fig. 3, ■). After that, the measurement data output code is given. The above operation is repeated to measure data of all codes.

From the above explanation, compared to the conventional system in which the control section is composed of three blocks, the present invention is simplified because it requires only one general-purpose computer. Furthermore, since the step width of step-up can be set arbitrarily, there is an advantage that measurement can be performed automatically at high speed (in a short period of time). In addition, since the measurement results are stored in an external storage device, quantization errors and linearity 2
It also has the advantage that various characteristics related to the A/D converter can be calculated immediately. Furthermore, regarding accuracy, there are very few factors in which errors in measurement system accuracy are added to the accuracy of the A/1) converter to be measured, and highly accurate measurement results can be obtained. As described above, since high-precision measurements can be easily performed in a short period of time, this method has great utility for manufacturers of A/D converters and users who frequently use them.

[Brief Description of the Drawings] Fig. 1 is a block diagram of a conventional block diagramger l1, Fig. 2 is a block diagram of an embodiment according to the present invention, and Fig. 3 is an 8-pin A/D converter as an example. The measurement operation time chart is shown below. In addition, in FIG. 1 and FIG. 2, 10... Standard voltage generator, 11... Control section, 12...
・Display device, 13゛pa... A/D converter to be measured,
200...Counter, 201...Register, 202...Control circuit, 20...
General-purpose converter, 21...external storage device. Figure 1 Figure 2 ■ ( Figure 3

Claims (1)

[Scope of Claim] A method for measuring input/output characteristics of an analog/digital converter, comprising: first means for generating an arbitrary standard voltage according to an arbitrary control signal and supplying it to the input of the converter;
a second means for detecting a change in the output sign of the converter and generating a control signal for the first means; and a third means for displaying and storing output contents of the first means and the second means. Including. An analog/digital converter characteristic automatic measuring method, characterized in that generation of a control signal of the first means, detection of an output code of the second means, and control of the third means are performed by a general-purpose computer.