SU943612A1 - Device for measuring transistor current gain - Google Patents

Description

(5) DEVICE FOR MEASURING THE GAIN COEFFICIENT ON TRANSISTOR CURRENT

one

The invention relates to a measurement technique and is intended to control the parameters of semiconductor devices, in particular for measuring the current gain of transistors, during their mass production.

A device for measuring the static current gain of transistors is known, comprising an emitter current source, a collector voltage source, a type of work switch, an amplifier, and a measuring unit l.

A disadvantage of the known device is the presence of a systematic error due to the finite value of the resistance of the resistor included in the base circuit of the tested transistor. Another disadvantage of the device is the low productivity due to the necessity of switching the measuring device (voltmeter) from the collector circuit to the base one during the control process.

It is also known a device for measuring the gain factor

J / current transistors). containing a source of emitter current and a collector voltage, resistors, a voltmeter, and a generator with a sine of a far voltage 2.

IQ. A disadvantage of the known device is the presence of a systematic error due to the finite resistance value of the resistor including the test transistor in the base circuit, low productivity due to the long voltage measurement time with a voltmeter.

Closest to the proposed

Claims (3)

20 is a device for measuring the current gain factor, comprising a controlled emitter current source, a collector voltage source, a current converter 39 to a voltage, made on an operational amplifier with a resistor in the feedback circuit, a recording unit, two capacitors and two synchronous switch G31. The drawback of the device is the relatively low measurement accuracy due to the difficulty of determining the output voltage increment as the difference of two close values. In order to provide highly accurate measurements, the voltage on the recall capacitors must remain constant between the measurement cycles. , The purpose of the invention is to improve the accuracy of measurement and expand functional capabilities. The goal is achieved in a device for measuring the current gain of transistors containing a control unit with a controlled emitter current source, the output of which is connected to a terminal for connecting the emitter of a transistor under investigation, to the terminal for connecting a collector of which a source of collector voltage is connected A current-voltage converter is connected to the terminal for connecting the base, the output of which is connected to the input of the computer unit connected to one input of the summation unit The input of the registration unit is in progress to one input, and the other input of the summation unit is connected to the output of the current-voltage converter, the control unit is connected to the control input of the memory unit, the output of which is connected to another input of the register unit. In FIG. 1 shows a functional diagram of the device; FIG. 2 time diagrams for his work. The device contains a controlled emitter current source 1, a control unit 2, a current converter 3, a collector voltage source C, a summation unit 5, a memory unit 6, a recording unit 7 and terminals 8, 9 and 10 for connecting the respective electrodes of the test transistor . The registration unit 7 is an amplitude value voltmeters, one of which is intended to measure the amplitude range of an alternating voltage proportional to 1 + h, and the other to measure a constant voltage proportional to the value I oi. The device works as follows. The controlled source 1 sets to the emitter of the tested transistor a pulse of current Ig modulated by a sinusoidal signal, coming from the output of control unit 2 (Fig. 2a). Source k provides the required mode on the collector, and the base current is converted by converter 3 into voltage (Fig. 26), which is supplied to the first inputs of blocks 5 and 6. Up to time point t. (figv) the memory block 6 operates in the mode of input signal investing with the transfer coefficient equal to -1, therefore the voltage n & its output is equal and opposite in sign to the voltage applied to its first input. As a result of adding the signals from the output of the converter 3 and the output of the block 6, the voltage at the output of the block 5 until the moment is zero (Fig. 2d). At the moment t, the block 2 produces a signal that transfers the block 6 to the memory mode at which the voltage level is U is stored and stored until time t ,. As a result of the addition of signals arriving at the inputs of block 5, the voltage at its output during the time t -tj is, where uU is the amplitude of the alternating voltage proportional to the change in the base current, k is the gain of the block 5. Thus, The output of block 5 to block 7 enters a zero voltage, reduced to zero, proportional to the change in the base current. For example, the measurement time of the parameter ha-te is determined only by the actual time of measurement t of the amplitude of the alternating voltage and is numerically equal to the duration There are several periods of the modulating signal, which is a few milliseconds. The use of a sinusoidal signal makes it possible to increase the noise immunity and eliminate measurement errors due to the flow of reverse collector current into the base circuit, i.e. this current does not affect the voltage k or li. From the output of block 6, block 7 of the registration receives a voltage pulse DO, proportional to the constant component of the base current of the transistor under test. . 1eo, Eo where k. - gain factor of converter 3, I - emitter current. Thus, the proposed device allows simultaneous measurement of the parameters b ,, and b2 in one measurement cycle, which expands its functionality. In addition, the proposed device allows measurement of a parameter on a modulating signal of any kind, for example, in the form of a series of rectangular pulses. The choice of the modulating signal is determined by the requirements of accuracy, speed and noise immunity: the device. The invention The device for measuring the current gain of transistors, comprising a control unit with a controlled source of emitter current, the output of which is connected to the terminal for connecting the emitter of the transistor under study, to the terminal for connecting the collector of which the source of collector voltage is connected, and to the terminal for connecting A current-voltage converter is connected to the base, the output of which is connected to the input of a memory unit connected to one input of a summation unit connected by an output to one To the input of the registration unit, in order to improve measurement accuracy and enhance the functionality, the other input of the summation unit is connected to the output of the current converter, the control unit is connected to the control input of the memory unit, the output of which is connected with another entry blszha registration. Sources of information taken into account during the examination 1. V. Lronov. and others. Testing and study of semiconductor devices. M., Higher School, 1975i p. 72-7. . 2. Aronov V.L. et al. Testing and investigation of semiconductor devices. M., Higher School, 1975, p. 97-103. 3. USSR author's certificate, cl. C 01 R 31/26, 1977.