SU1506402A1 - Method of determining the gain of high-voltage transistor - Google Patents

Abstract

The invention relates to the field of semiconductor instrumentation and can be used to measure the gain of high voltage transistors. The purpose of the invention is to improve the accuracy of the method by supplying a base current I _b to the transistor with an amplitude equal to half the amplitude of the current collector I _c and a duration of at least five times the lifetime of the carriers in the collector. By reducing the amplitude of the base current pulse and registering the voltage transient characteristic between the collector and emitter, fix the base current amplitude at which the transistor resorption time is equal to the recovery time of the equilibrium collector resistance and the force coefficient is calculated. The increase in the accuracy of the method is due to the fact that with equal absorption times and restoration of the modulation of the collector conductivity of the high-voltage transistor occurs across its entire width. 1 il.

Description

The invention relates to the field of semiconductor instrumentation and can be used to measure the gain of high voltage transistors.

. The aim of the invention is to improve the accuracy of the method.

The essence of the method lies in the fact that a collector 1 current pulse, a given amplitude and an Ig base current pulse with an amplitude equal to half the amplitude of the collector current pulse, and with a duration of at least five values, pass through a transistor connected according to a common emitter circuit.

the lifetime of the carriers in the collector (holes for pnp-n-transistors). Register transfer, o. the voltage characteristic between the collector and the emitter reduces the base current amplitude to a value at which the high voltage transistor tp dissipation time becomes equal to the recovery time of the collector's equilibrium resistance t, fixing the magnitude of the base current 1 and determining the transistor gain coefficient using the formula

/ IjlsSL

About O5

one

about

HS

Figure 1 shows a diagram of the device for implementing the method; Fig. 2 shows the diagrams of the base current) and the collector L | (t), as well as the diagrams of the transient characteristic of the voltage of the high-voltage transistor U (t).

Improving the accuracy of the method is due to the fact that the mode at which the gain is measured is much more precisely set, the tp tg mode. Setting the pulse mode (prototype) is a difficult technical task and introduces a significant error in the measurement / 3.

With the proposed method, there is no source of error associated with heating the test transistor during the measurements, since the method does not require the formation of long base current pulses during the implementation of the method.

Mode

tf

t d (curve b, figure 2)

due to the fact that in this mode the modulation conditions of the high-voltage transistor collector conductivity are realized exactly across its width. If t p t, then the test transistor is in a mode with excessive modulation of the collector conductivity (curve a, Fig. 2).

The initial value of the base current is set equal to half the collector current in order to deliberately put the transistor in a mode with excessive modulation of the collector conductivity. In this mode, tp t, and the switching power loss in the transistor is small. Thus, the mouth

A new initial value of I 0.5 1, excludes the source of the error due to the heating of the transistor under test. Since when I 0.5 I at the voltage transient response, both stages of the transistor turn-off process are easily expressed, then further, when the base current decreases, it is more accurate to establish a mode in which the dissolution time of the high-voltage transistor becomes equal to the recovery time of the equilibrium collector resistance. The duration of the base current is set to not less than five values of the lifetime of holes in the collector (for pnp transistors) t 5 G., / 1, so that the gain is measured

under conditions close to stationary and not causing the subject to heat

device. If tgX g / 1

 - i-p

THAT increases the error of determination of / 3 due to unreliable transients. If, then the transistor may be heated during the measurement time and the airflow error of the determination of the gain. Values 1

Ik

installed ex 0.5

perimentally for a large number of high-voltage transistors of different types.

A device for implementing the method contains a stabilized constant voltage source 1, a block of 2 high-precision resistors, a generator of 3 base current pulses, a high-voltage transistor 4 under test, and an electron-beam oscilloscope 5. In the device are non-potential outputs of source I, generator 3 and oscilloscope 5, and The emitter of the test transistor 4 is connected by a common bus, which is under zero potential. The potential output of source 1 is connected to the output of the resistor unit 2, the other output of which is connected to the test collector uemogo transistor 4 and Y input of the oscilloscope 5, and the potential output generator 3 is connected with the base of the transistor under test 4. The electrical circuit device following parameters: voltage source voltage

10 and

k er

ak

er

boundary

the value of the voltage at which the transistor is located at the boundary, between the amplification modes and the maximum;), the duration of the base current pulses.

five

five

0

formed by generator 3, t..7 / (p5x1 1-1

p is the lifetime of holes in the collector), the pulse frequency is a few hertz. The condition E 10 Uiorp provides a slight drop in the collector current in the transistor during the absorption phase. The condition, 5 p ensures the establishment of the operating mode of the transistor, close to stationary. The low frequency of operation of the generator 3 eliminates the heating of the test transistor during the measurement.

The gain of the high voltage transistor using the device is determined as follows.

A test transistor 4 is connected to the device (FIG. 1). The source is switched on: I, generator 3 and oscilloscope 5. Through source I, resistor unit 2 and generator 3, the external circuit is set so that the current for the test transistor collector I is equal to the specified value, E

 10 and

k P Gr

1 - 0.5 1, tjf

5Ср. On

Oscilloscope screen 5 get a stable image of the transient voltage characteristic of the transistor (curve a, Fig.2). Reducing the amplitude of the base current by the generator 3, by oscillogram) sets the operation mode of the tested transistor, in which the resorption time is equal to the recovery time of the collector equilibrium resistance (curve b, Fig. 2)

ten

five

064026

Claims (1)

Invention Formula A method for determining the high voltage T1 anzisistor amplification factor, which includes passing through a transistor connected by a common emitter circuit, a current pulse of a given amplitude and a base current pulse, characterized in that, in order to increase the accuracy of the method, a base current pulse with an amplitude equal to half the amplitude is passed the collector current pulse, and with a duration of at least five times the lifetime of the carriers in the collector, measure the transient response of the voltage between the collector and the emitter, mind shayut base and amplitude of the current pulse CONST In this mode, when tp t j, the measurement is 20 RUO value at which time The amplitude of the base current Ig is applied, after which the gain of the high voltage transistor is calculated from the ratio / i. the resorption of the high voltage transistor becomes equal to the recovery time of the collector equilibrium resistance. the resorption of the high voltage transistor becomes equal to the recovery time of the collector equilibrium resistance. 1 U  kegr