SU879602A1 - High-speed converter of two voltage ratio to code - Google Patents

Description

one

The invention relates to the field of information-conversion, computing and measuring equipment and can be used in the construction of high-precision ratio meters, frequency meters, phase meters, functional transducers, right angular coordinate AC compensators, Q-meters, loss cosine, and other electronic equipment.

A known converter is a ratio of two voltages G0 containing an amplifier, large-scale resistors, a controlled pulse generator, an adder, keys, and a filter capacitor.

The known converter has a good conversion accuracy, which is achieved by reducing the speed, since it contains integrating devices and other inertial units. Increasing the speed of the known converter leads to a decrease in the accuracy of work.

The closest to the technical essence of the invention is a ratio converter 23, built on the basis of a parallel-to-analog-to-digital converter (A / D converter) and a content register at the output, the outputs of which are connected to output pins.

The use of ADC ratios, especially parallel ones, makes it possible to increase the speed of voltage conversion L) and UQ to a code of N proportional to the ratio of these voltages by several orders of magnitude (up to microseconds).

However, the known converter based on the ADC has a limited dynamic range of input voltages and insufficient conversion accuracy due to the nonidentity and instability of the characteristics of the voltage comparators, the variation of the parameters of the elements of the matrix, the limited range of input voltages of the comparators, etc. The aim of the invention is to extend the dianamic range the voltage of the generated stresses and increase the accuracy of work. The goal is achieved by the fact that in a high-speed converter the ratio of two voltages to a code containing an ADC and a register whose inputs are connected to the outputs of the ADC, and the outputs of the register are the output of the converter, a correction block, a voltage divider, an operational amplifier and a digital-to-analog input are entered. Converter (DAC), the digital inputs of which are connected to the corresponding outputs of the ADC. The DAC output is connected to the inverter common input, the op amp foot and to the first input of the correction unit, and the analog DAC input and the first ADC input are combined and connected to the output of the voltage divider, whose input is the first input of the converter. The second input of the correlation unit is the second input of the converter, and the output is connected to the noninventing input of the operational amplifier, the output of which is connected to the second input A1D1. This goal is also achieved by the fact that the correction unit contains successively connected voltage divider, operational amplifier and adder, the inverting input of the operational amplifier being the first input of the correction unit, the voltage divider input being the second input of the correction unit and connected to the second input adder, the output of which is the output of the correction unit. A functional diagram of a high-speed converter for the ratio of two voltages to a code is shown in the drawing. The converter contains voltage divider 1, operational amplifier 2, ADC 3, DAC 4, register 5, correction unit 6, which contains voltage divider 7, operational amplifier 8 and adder 9. Voltage divider 1 input with the first input of converter, and the output is connected to the analog input of the D / A converter 4 and the first input ASCh1 3. The input of the voltage divider 7 is connected to the second input of the adder 9 and is the second input of the correction unit. The output of the voltage divider 7 is connected to the inverting input of the amplifier 8, the non-inverting input of which is the first input of the correction unit and connected to the inverting input of the amplifier 2 and to the output of the DAC 4. The output of the amplifier 8 is connected to the first input of the adder 9 whose output is the output of the block correction and connected to the non-inverting input of the amplifier 2. The output of the amplifier 2 is connected to the input of the ADC 3, the outputs of which are connected to the digital inputs of the DAC A and the inputs of the register 5, the outputs of which are the output of the converter. The Converter operates as follows. The input voltages are applied to voltage divider 1 and 7. The division factors of voltage divider 1 and 7 are chosen equal to K 1/2. At the same time, the voltage of the first input signal is fed to one of the inputs of the adder 9, correction unit 6. The analog inputs of the ADC 3 and DAC 4 receive voltage from the output of divider 1. Consider the operation of the inverter without the correction unit 6, considering that the first input signal enters directly to the inverting input of amplifier 2, to the non-inverting input of which voltage is supplied from the output of the DAC 4. As a result, a voltage equal to the voltage difference at the first input of the converter and the voltage at the DAC output 4 ond ADC 3 is converted to N. Next, the code number Code N data inputs to the register 5 and to control inputs of DAC 4. DAC 4 analog input receives a voltage proportional to the second half of the input voltage (since K 1/2). . A voltage proportional to the N code is formed at the DAC output. If you write mathematical expressions for the code at the ADC and DAC output and consider that the proportionality coefficient depends on the ADC and DAC resolution and the conversion method implemented by them, it can be shown that the output code of the number The Ny converter is proportional to the ratio of the voltages at its inputs.

To improve the accuracy of the conversion, a correction block 6 has been inserted into the converter.

Suppose that the conversion of a voltage into a code and a code into a voltage h is performed by an ADC and DAC with a certain error di. Then at the output of the DAC we get

Vn itzAp + di.

To eliminate the error, the voltage U is transformed by a factor of two by means of a voltage divider 7.

As a result, at the output of the correction block, a reference voltage is formed equal to half of the first input voltage, which is fed to the inverting input of the amplifier 8. To its non-inverting input nociynaeT, the voltage from the DAC output is inaccurate. In this case, a differential voltage is formed at the output of the amplifier 8.

,.di)-,

which is used as a correction and is summed with the input voltage in the adder 9.

As a result, the non-inverting input of amplifier 2 receives voltages U-I and +, and the inverting input receives voltage ui, lg. When you subtract them, the input to the ADC 3 receives voltage

.,). An + uU) 4

4 and, - (c

in which there is no inaccuracy.

Thus, in the proposed technical solution, the expansion of the dynamic range of the converted voltages in 2 times is achieved by using as a reference voltage ADC and DAC voltage, two times smaller than the voltage of the divider. The automatic reduction by two times of the voltage level of the divisors is ensured by performing, by means of the operational amplifier 2, the operation of subtracting the voltage generated by the DAC from the input voltage of the separable.

Improving the accuracy of the conversion is achieved by introducing a correction block that ensures the formation of a correction voltage.

Thus, the introduction of a voltage divider converter, opera 796026

Amplifier, D / A Converter and Correction Block allows you to expand the dynamic range of the voltages being transformed and 5 to improve the accuracy of operation.

Claims (2)

1. Author's certificate of the USSR No. 523416, cl. G 06 G 7/161, 1974. 2. Drozdov EA, P tibratov A.P. Automatic conversion and encoding of information. N., Soviet Radio, 1964 p. 261-262 (prototype). Ttf 7 eight 7G and Vz / Y t U