SU788377A1 - Voltage-to-digital code converting device - Google Patents

Description

I

The invention relates to computing and measuring technology.

A digital-to-analog converter is known, which contains a comparison unit, the first input of which is connected to the input bus, the second input through a digital-analog converter is connected to the output of a reversible counter, and the output is connected to the first inputs of the first and second elements I, the second inputs of which are connected to the output of the pulse generator, and the outputs connected respectively with the first and second outputs of the OR element and the trigger, while the OR element is connected to the first input of the reversible counter, the second input of which is connected to the output of the trigger I.

A constant and slowly varying voltage by a known converter is converted into a sequence of different-polarity pulses with a duration equal to the period of the clock pulses. Since a change in the state of a trigger occurs at the instants of time corresponding to the first clock pulse after the extremum of the signal, the periodic triggering of the trigger leads to the appearance of false extrema that do not actually have a transformable voltage.

The purpose of the invention is to improve the accuracy of the conversion.

The goal is achieved by the fact that the device for converting voltage into a numerical code containing the first comparison unit, the first input of which is connected to the input signal, and the second

10 input through a digital-to-analog converter connected to the output of a reversible counter, the first input of which is connected to the output of the OR element, and the second input to the trigger output, the first and second inputs of which are connected respectively to the first

15 and the second inputs of the OR element, the second comparator unit and the voltage shaping unit are introduced, the input of which is connected to the output of the digital-to-analog converter, and the output to the first input of the second comparison unit, the second input of which is connected to the input signal bus, and , the second input of which is connected to the output of the first comparison unit.

The drawing shows a block diagram of a device for converting a voltage into a numerical code.

The device contains the first and second blocks of comparison 1 and 2, the voltage shaping unit 3, the element OR 4, the trigger 5, the reversible counter 6, the digital-to-analog converter (D / A) 7.

The device works as follows.

The input voltage is compared in comparison unit 1 with the feedback voltage from the DAC output 7 equal to V, and in comparison unit 2 with the same voltage reduced in magnitude by the quantization step in terms of V - li.

A counting pulse appears at the output of the comparison blocks at the time of equality of the compared voltages. At the moment of capture, the input voltage must be less than the voltage at the output of the D / A converter 7 and more than the voltage supplied to unit 2.

If the input voltage increases, then at the moment of equality of the voltages at the output of the comparison unit 1, a counting pulse appears on the trigger, forming a pulse of the counting sign, which then goes on the reversing counter 6. The value of the numeric code recorded in the meter increases by the unit and the output voltage of the DAC 7 will increase by a quantization step and the input voltage will again be in the capture position. As the input voltage increases further, the tracking process is repeated.

If the input voltage starts to decrease, then at the time of equality of the compared voltages, a counting pulse appears at the output of the comparison block 2, relocating the trigger to the opposite state, and the reversible counter counts the pulses with a minus sign. The value of the numeric code in the counter decreases by one, and the voltage at the output of the DAC 7 decreases by a quantization step. As the input voltage decreases further, the tracking process is repeated. Note that the counting pulses appear at the output of the comparison blocks with a variable frequency, which depends on the rate of change of the voltage to be converted (the higher the speed, the greater the frequency of the pulses).

The trigger moves from one state to another at times of current extremes of the input voltage, and the numeric code in the reversible counter corresponds to the current value of the input voltage. The discreteness error in this case depends only on the quantization step on the level, while in the well-known it also depends on the discretization step in time determined by the frequency of the clock generator.

The device is advisable to use in electrical measuring equipment when it is required to accurately fix the position and value of the current extremes and the shape of the random voltage under investigation, for example, when processing signals of biomedical information.

Claims (1)

Invention Formula A device for converting voltage into a numeric code containing a first comparison unit, the first input of which is connected to the input signal bus, and the second input through a digital-to-analog converter connected to the output of a reversible counter, the first input of which is connected to the output of the OR element, and the second input to the trigger output , the first and second inputs of which are connected respectively to the first and second inputs of the OR element, characterized in that, in order to improve the accuracy of the conversion, a second comparison unit and a shaping unit are introduced and a voltage input coupled to an output of the digital to analog converter, and an output to a first input of the second comparator unit, the second input of which is connected to the input bus and the output - to the first input of the OR gate, a second input coupled to an output of the first comparator unit. Sources of information taken into account in the examination 1. "Computing technology, Minsk," Science and technology, 1965, p. 353-361.