SU586393A1 - Ac -to -ac voltage ratio meter - Google Patents

Description

one

The invention relates to a measurement technique, in particular, to apparatus for calibrating attenuators, removing normalized frequency characteristics, and can also be used to measure (Ru) - the transistor gain module at a high frequency, the capacitors of the collector and emitter transitions of transistors, time constant transistor feedback circuits.

A device for measuring the ratio of two alternating voltages using separating circuits is known.

The device has a large error due to the nonidentity of the differential resistances of the adjustable transistors, the nonlinearity of the amplitude detector, the residual values of the uncompensated input current and the voltage on the collector of the transistor of the first dividing circuit, the nonlinearity of the frequency conversion, and the difference in the transfer coefficients of the reference and measurement signals.

The closest technical solution to the invention is a device that contains a measuring channel with a detector, a null organ, a reference channel with a reference signal generator and a calibrated attenuator.

Such a setup has an error due to the linearity of the frequency conversion and the calibration of the exemplary precision attenuator at a relatively high intermediate frequency, as well as the error due to the instability of the amplitude of the reference oscillator and, moreover, the measurement requires modulation of the signals.

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

The goal is achieved by the fact that a device for measuring the ratio of two alternating voltages containing a measuring channel made as a series connection of two non-switches, a detector and a zero-organ, and the output of the detector through a third switch the non-switch is connected to a memory capacitor connected to the second input of the zero-organ, as well as the reference channel, made in the form of a series connection of the reference voltage generator and an attenuator, and a control unit associated with the control inputs of the attenuator switches and the zero-organ output, an additional attenuator is added, the signal input of which is connected to the output of the main attenuator, the input to one of the terminals of the second switch, and the control input is connected to control unit.

The introduction of an additional attenuator made it possible to refuse to transform the frequency of the measured signal into an intermediate one, where an error occurs due to the non-linearity and transformation of the EMOio b-channel measurement, especially large amplitude, and allowed to eliminate blues due to the instability of the amplitude of the reference generator and the non-linearity of the amplitude detector. Due to the high input resistance of the detector, the device can measure the transmission coefficient of high-resistance devices.

The drawing shows a functional diagram of the proposed device for measuring the ratio of two alternating voltages.

The device contains a reference signal generator 1, two precision attenuators 2 and 3, an amplitude detector 4, a zero-body 5 with a memory, a charging capacitor 6 and three keys 7–9 for switching signals controlled by the automation unit 10.

The device works as follows.

The attenuation coefficients of attenuators 2 and 3 are set to one. The automatics unit 10 supplies the measured voltage Ui to the detector 4 and the detected voltage f / i is recorded on the storage capacitor 6 of the null organ 5. Switch 9 is turned off, switch 8 is switched, and attenuator 2 transfer coefficient is changed as long as the detected reference signal is not compared with the detected voltage U, which is fixed by null 5.

This achieves the equalization of the coefficients and the transmission of the detector at the frequencies of the measured and reference signals.

With further measurement, the transfer ratio of the attenuator 2 remains izmennaya. Then switches 8 and 9 are closed in the initial position, and switch 7 is closed in the measurement region Uz, capacitor 6

charged by the detected voltage; t / 2. 1c) Keys 9 and 8 and a division factor are excluded. the attenuator 3 is changed by the automation unit 10 until the value of the detected reference signal is equal to the voltage value

on the capacitor G f / 2. The value of

t / 2.

The ratio of two iair zhein will be equal to

t / i

division factor of the attenuator 3. Measurement error of the ratio of two f / 2

determined by dolmen voltage

and.

to the sensitivity of the null organ 5 and the precision of the precision attenuators 2 and 3.

When using a set of equipment to measure the dynamic parameters of power transistors, the measurement error is reduced to 0.05% while the known device has an error of 1.1%.

Claims (1)

Invention Formula A device for measuring the ratio of two alternating voltages, containing a measuring channel made as a series connection of two switches, a detector and a null organ, the sources of the tested voltages are connected to the terminals of the first switch, and the output of the detector is connected via a third switch to a memory capacitor connected to the second input of the zero-organ, as well as the reference channel, made in the form of a serial connection of the reference voltage generator and attenuator, and the control unit, with It is equipped with the additional inputs of the attenuator switches and the zero-body output, characterized in that, in order to improve accuracy, it is equipped with an additional attenuator, the signal input of which is connected to the output of the main attenuator, the output to one of the terminals of the second switch, and the control input connected to the control unit.