SU1083136A1 - Uhf transistor parameter measuring method - Google Patents

Abstract

METHOD OF MEASURING THE PARAMETERS OF UHF-TR SISTORS, which includes applying a microwave signal to the input of the transistor, providing the required operating mode of the device under test, and at its output an auxiliary signal that is much smaller in amplitude, and recording the amplitudes of the incident and reflected waves at the input and output of the transistor , characterized in that, in order to simplify the measurements, the signal of the same frequency as the working one is used as an auxiliary signal, it is modulated in amplitude by a low frequency, and the amplitudes are padak and their reflected waves measured at the frequency of modulation.

Description

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The invention relates to a measurement technique and can be used in the manufacture and testing of high power microwave transistors. There is a known method for measuring the vapor; the meters are scattered by transistors, which consists in that a small amplitude microwave signal is applied to the test transistor and the amplitudes of the reflected and transient waves lj transmitted through the transistor are measured. The disadvantage of this method is its low accuracy, measurements in a large signal mode, which is characteristic of high power transistors. This is due to the fact that the scattering parameters of such transistors in the large signal mode depend on the amplitude of the input signal and therefore, when a small amplitude measuring signal is applied, the measured parameters are significantly different from the real ones that should be obtained in the large signal mode. The closest technical solution to the present invention is a method for measuring the parameters of microwave transistors, including the supply to the transistor of a microwave operating signal, providing the required mode of operation of the device under test, and at its output an auxiliary signal, much smaller in amplitude, and recording the amplitudes of the fallan and reflected waves at; the input and output of the transistor L As an auxiliary measuring signal of small amplitude in this method, use a signal that differs in frequency from the large of the signal. The disadvantage of this method is the difficulty of measurement, due to the need to use frequency selective equipment with high requirements for its selectivity in its implementation. This drawback is especially apparent when measurements are needed in the frequency range, when additional adjustment is required of both the auxiliary signal source and the instrumentation in synchronization with the operating signal. The purpose of the invention is to simplify the measurements. This goal is achieved by the fact that, according to the method from the one-pair para- graph, 362 meters of microwave transistors, including the supply to the input of the transistor a microwave signal, providing the required operating mode of the device under test, and at its output, an auxiliary signal that is much smaller in amplitude, and recording the amplitudes of the incident signals. and reflected waves at the input and output of the transistor, as an auxiliary signal, use a signal of the same frequency as the working one, modulate it in amplitude with a low frequency, and amplitudes are incident Reflected waves are measured by the modulation frequency. The drawing shows a block diagram of a device for implementing the method. The device contains a working microwave signal generator 1, the first output of which is connected to the first bus of the contact head 2 for connecting a test transistor, the second bus of which is connected to the output of the transistor power supply 3, and a third through serially connected directional couplers 4-6 included in the microwave transmission lines power, is connected to the matched load 7, the second output of the generator of the working microwave signal is connected via an attenuator 8 to the first input of the modulator 9, the input of which is connected to the output of the generator and 10 is low frequency, and the output is g with the input of the coupler 6, the inputs of the couplers 4 and 5, respectively, are connected via series-connected detectors, II and 12, and the selective amplifiers 13 and 14 with the first and second inputs of the ratio meter 15, the output of which is connected to the indicator 16. Method carried out as follows. From the generator 1 of the working microwave signal, through the contact head 2 to the input of the transistor under test, a working microwave signal of large amplitude is generated, which creates the required operating mode of the transistor. From source 3, the required supply voltage is applied to the device under test at the same time. Through the output path of the test transistor, including directional couplers 4-6 and matched load 7, an auxiliary measurement signal is supplied to the output of the test transistor, which is used as the working sig3. ten

This signal is attenuated by attenuator 8 and modulated in amplitude with the help of modulator 9 by a signal from a low-frequency generator 10. The amplitude of the auxiliary measuring signal, which is led into the output path through the coupler 6, is significantly less than the amplitude of the main mode signal.

With the help of directional couplers 4 and 5, microwave signals with a high-frequency modulating signals superimposed on them are proportional to the reflected (using a coupler 4) and incident (using a coupler 5) waves in the output path. The detectors 11 and 12 convert the microwave signals into low frequency voltages, which are amplified and amplified by selective amplifiers 13 and 14. In this case, the amplitude of the low frequency voltage with the modulation frequency at the output of the amplifier 13 is proportional to the amplitude of the reflected wave at the output of the transistor under test

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and the amplitude is similar to that of 2,.

The output pitch of amplifier 14 is proportional to the amplitude of the incident wave of the auxiliary measuring signal.

Due to the fact that the output impedance of the generator. 1, the working signal is equal to the wave contact of the input line connecting this generator with the contact head 2, the auxiliary measuring signal passing from the output to the input of the transistor under test does not reflect from the matched load

(output impedance generation364

torus 1) and therefore the amplitude of the falling

waves

at the input of the transistor is zero.

As a result, the indicator 16, included in the ratio meter 15, directly indicates

magnitude

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equal to the module of the reflection coefficient at the output of the transistor under test (in the above notation, indexes 1 and 2 characterize the belonging of the signal to the input and output of the transistor, respectively).

To measure another scattering parameter of the transistor, the return transfer coefficient 842, directional coupler 4 is switched to the input line between the output of the generator 1 and the contact head 2. At the same time, the indicator 16 shows the value

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Due to the use of an amplitude-attenuated and low-frequency modulated operating signal as an auxiliary measurement signal, the measurement of the scattering parameters of transistors in the frequency range is simplified. When tuning the frequency of the oscillator 1, the remaining blocks of the device used to carry out this method are not required, but the indicator 16 directly shows the measured value.

Claims (1)

METHOD FOR MEASURING MICROWAVE TRANSISTOR PARAMETERS, which includes applying to the microwave transistor an operating signal that provides the required operating mode of the device under test, and its output - an auxiliary signal that is much smaller than the working amplitude, and recording the amplitudes of the incident and reflected waves at the input and output of the transistor, characterized in that, in order to simplify the measurements, a signal of the same frequency as the working one is used as an auxiliary signal, modulate it in amplitude with a low frequency, and the amplitudes of the incident and reflected waves are measured at a modulation frequency.