SU1262727A2 - A.c.voltage calibrator - Google Patents

Abstract

The invention is intended to create low frequency ac voltage calibrators and is complementary to auth.s. No. 900464. The purpose of the invention 1 and - pov-. understanding the accuracy of the device. The calibrator includes a master oscillator, a regulating unit 2, a power amplifier, a power 4, a comparator 5, a voltage source 6, an error amplifier 7, an attenuator 8, an integrator 9, and a multiplication unit 10. The introduction of rectifier 12, integrator 13 and adder 14 compensates for the low-frequency error. With the introduction of the adder 15, it becomes possible to use the calibrator as a precision alternating voltage source with a calibrated level & there is nonlinear distortion. 1 hp f-ly, 1 ill. (L

Description

Yu

I

The invention relates to radio measurements, is aimed at creating low-frequency calibrators of alternating voltage and is an improvement of the known device according to the author. No. 900464 ,.

The aim of the invention is to improve the operation accuracy by compensating for low-frequency error, extending the functionality by allowing the device to be used as a precision alternating voltage source with a calibrated level of non-linear distortion. I

The drawing is structural

electrical circuit device.

The ac voltage calibrator contains a master oscillator 1, the output of which is connected to the input of the regulating unit 2, the output connected to the output bus 3 via the power amplifier 4, the comparator 5, two inputs of which are connected respectively to the source 6 of the reference voltage and the output bus 3, and the output through the error amplifier 7 to the control input of the regulating unit 2, connected in series between the output bus 3 and the second input of the error amplifier 7 adjustable attenuator 8, integrator 9, multiplication unit 0, second The input of which is connected to the output bus 3, the separator capacitor 11, the first lining of which is connected to the output of the multiplication unit 10, the second lining to the non-inverter input of the error amplifier 7, the rectifier 12, an additional integrator 13, the first adder 14, the first input and output included between the second plate of the coupling capacitor 1 and the non-inverting input of the error amplifier 7, the second input of the first adder is connected to the output of Mitel 12, the input of which is connected to the output of the additional integrato and 13, whose input is connected to the output of multiplier 10, a second adder 15, included its first input and output between the output of the regulating unit 2 and the input of the power amplifier 4, and a second input of the adder I5 is connected to the control bus 16.

The device works as follows.

627272

I The signal from the output of the master oscillator I is fed to the output bus 3 through the regulating unit 2, the adder 15 and the amplifier 4 power to the bus

5 16 signal from the input of the calibrator. The control signal for the regulating unit 2 is formed at the output of the error amplifier 7, the non-inverting input of which is supplied by the signal from the output of the comparator 5. The latter compares the variable signal from the output bus 3 of the calibrator and the constant signal from the output 6 of the reference voltage of 15 times. The non-inverting input of the amplifier 7 mismatch through the adder 14 receives signals that compensate for the voltage of the second harmonic and the error of comparing

20 in the low frequency region.

The signal from the output bus 3 is fed simultaneously to input 17 and through an adjustable attenuator and integrator to input 18 of unit 10 multiply 25, the output of which through the capacitor 11 receives the first input and through the integrator 13 and the transmitter 12 to the second input of the adder 14. The principle of compensating for low-frequency 30 comparing errors is based on the formation of a constant voltage, the amplitude of which varies with the frequency of the master oscillator according to the same law,

5 that the low-frequency comparing error. For this purpose, an integrator 13, rectifier 12 and adder 14 are additionally introduced into the calibrator.

0 In the actual circuit, these nodes can be implemented, respectively, on the basis of the RC circuit, peak detector and resistive adder.

The output voltage of unit 10 um5 the legs can be represented as

UBb, xJt) Z8b ,,, (t) ,,,, (t) -Kg. K, .K, „,

Where Ugy (t) is the output voltage

block 10 multiply;

0 l ebix- t) output voltage

bus calibrator 3; Kg-K, g - transfer coefficients of an adjustable attenuator 8, integrator

59 and block 1C, respectively.

Claims (1)

The transfer coefficient of the integrator 9 is equal to 1/1 1 k., I is when with L 1, iuo s where Lg is the time constant of the integrator 9, Since Kg and K | g are constant values and the output voltage of the integrator is shifted angle tf 90 relative to the voltage at its input, o as a result of multiplying the quadrature voltages at the output of multiplication unit 10, we obtain /. T Den tg about (t} ---- X-Sin 2ot ..., 3 QCqJ where f is the total transfer coefficient of the blocks of the attenuator and multiplier. If the integrator transfer coefficient module 13 is represented as, --- for Wo, u (us , r where K ,, is the modulus of the transfer coefficient of the integrator 13; tl.j is the constant of the time of the integrator 13; then the voltage at the output of the miter 12 is 2 II 5 UsbiX tj, r (utj (ue; r where В - conversion factor of rectifier 12, In the proposed device for compensating the low-frequency error, the voltage from the output of the slider 12 Ujy through the adder 14 is fed to a non-inverted The mismatch amplifier 7 input. At the same time, the phasing of the Ugbixio Uewxij voltages at its inputs is such that not the frequency error is compensated. Thus, the formation of a constant voltage with the power of the integrator 13 and center 12 reduces the low-frequency error and increases accuracy with this power. calibration of the output voltage of the calibrator. In order to expand the functionality of the calibrator, an adder 15 is additionally introduced into it, 16 supplying the bus 16 voltages often times the frequency of the output voltage of the master oscillator ora 1, the voltage on the bus 3 of the calibrator will be 1262727; where 5 10 where Ugj and K mon one nap 4 g, (t) U ,,,, (t) 4Ue ,,, (t), Ug ,, | (t) is the voltage of the 1st harmonic in the spectrum of the output signal; (voltage of the pth harmonic in the output signal spectrum; n is the harmonic number. because Uey, (t) K -Kg-U8, (t), K (, is the gain of power amplifier 4; Kg is the transfer coefficient of the adder 15 ; t) is the voltage h of the harmonics on the calibrator bus 16,, Kg-const, then the level of the harmonics in the output signal spectrum is determined by the amplitude of the voltage on the bus I6. If Ugy, (t) ZI U, ncot, TO the nonlinear distortion factor of the output voltage of the calibrator is defined. is done as I. .. l | Uir + Uo, r +. . Cg - 4i + and „+ ...: where K is the nonlinear distortion coefficient; , “-, iV. and and, - the amplitudes of the harmonic components, I, And since Ufr + Ujr-U -b ... const, since it represents the output voltage of the calibrator, due to the introduction of the adder 15, it becomes possible to use the calibrator precision variable voltage source with a calibrated level of nonlinear distortion. Thus, in the variable voltage calibrator, the accuracy of the output voltage calibration and its functionality are improved by the input of the integrator, the level of the mittel, the first and the second adders. Claims 1. AC voltage calibrator according to auth.St. No. 900464, characterized in that, in order to increase work accuracy by compensation of low-frequency error, it introduced an amplifier, an additional integrator, the first adder connected between the coupling capacitor and the non-inverting input of the matching amplifier, the second input of the first adder connected to the output of the rectifier, the input of which is connected to the output of the additional integrator, the input of which is connected to the output of the multiplication unit. 2627276 2, The calibrator according to claim 1, characterized in that, in order to extend the functionality by providing the device 5 with the ability to use the device as a precision source of alternating voltage with a calibrated level of nonlinear distortion, a second adder connected by the first 10 input and output between the output is entered into it. the regulating unit and the input of the power amplifier, and the second input of the adder is connected to the control bus.