SU655997A1 - Transistor recovering time measuring device - Google Patents

Description

The invention relates to the field of measurement technology and can be used for output control and product screening, input control, as well as in research laboratories in the development of transistor-based pulse circuits.

A device is known for measuring the transient time in a transistor, which contains power sources And mixing, a pulse generator, and an indicator i.

Measuring ts using a pulse generator and a time interval meter (especially fast-finding transistors) encounters serious difficulties associated with the necessity of obtaining pulses with steep edges and providing a very wide bandwidth of time interval meters. Such devices are usually complex, expensive, and provide a relatively low measurement accuracy.

Some simplification of measurements tg provides a device on the technical solution to the proposed meter and contains a pulse delay line connected to the indicator and switch, whose output is connected to the base of the test transistor, a source of power connected to the collector of the test transistor 2 through the reference transistor.

In this device, the falloff delay of the collector current of the transistor when a blocking current differential is applied to the base (i.e. the resorption time tg is converted into a change in the oscillation period of the ring oscillator into which the test transistor is.

Claims (2)

However, in the known device the oscillation period depends; only from the resorption time tg, but also from the delay in the rise of the collector current when the transient unlocking current differential is applied to the base of the test, which is a function of the constant, this causes an error in measurements reaching 5-8%, in some cases may be unacceptable. In addition, the need to calibrate the device using reference transistors complicates device setup and exodulation. The purpose of the present invention is to improve measurement accuracy, there is no need to calibrate the device. For this, a controlled current source, a discriminator of the current source, whose output is connected to the line delay, and the input is connected to an adjustable current source and a second output of the current switch and through a resistor “to the collector of the transistor under test. Fig, 1 shows the structural scheme of the proposed meter; Fig 2 is a functional circuit of a current switch; FIG. 3 shows timing diagrams of the meter. The proposed transistor resorption time meter contains (FIG. 1) a pulse delay line 1 connected to a current indicator 2 and a transistor switch 3, the first output of which is connected to the base of the transistor 4 under test. The collector of the transistor 4 under test is connected to the power source 6 and through a resistor 7 - with the second output of current switch 3, adjustable by source 8: current and input of current discriminator 9, the output of which is connected to the input of delay line 1. The meter works as follows. When a current (Fig, 1, 2) receives a positive differential (Fig. 3, a) at the input switch 3, the transistor T (Fig. 2) closes and unlocking current 16 flows into the base of the current transistor 4 from the first output of the current switch 3. (FIG. 3,6), the Transistor T opens the current G, (FIG. 2) from the second output of the current switch 3 to the current discriminator 9 (FIG. 3, c). At the output of the current discriminator 9 negative differential (fig, 3, a), which is hindered by a circuit of series-connected 1x logic circuits 1 and after time tj appears an inlet for swi 3 .l current. At the same time current 1; is switched from the second output of the current switch 3 to the first (from the transistor T to the transistor T -Fig. 2) and a locking differential enters the base of the test transistor 4 (FIG. 3.6); the voltage to the collector of the test transistor 4 begins to increase with time equal to the resorption time tg- (fig. 3.g). This voltage is converted by means of rezerm 7 to a current that is fed to the input of the current discriminator 9 (fig. 3, c ;,. When the sum of the adjustable current source 8 and the current through the resistor 7 at the input of the discriminator 9 current will be equal to zero, on it you during Wits positive voltage drop (Fig, 3, d). We assume that the current discriminator 9 operates u: and passing a zero level signal at its input. The current 12 of controlled current source 8 is selected depending on the reference level. at the level of (0.1 - 0.3) E, where E is the voltage of power supply source 6. To eliminate the influence of the readout devices on the measurement mode, the resistance of resistor 7 must be significantly greater than the resistance of resistor 5 (at least one - two times), so the current is 1, choose a ratio of OI /I,/(0,140,.- th. K and R2 - resistance of resistors 5 and 7, respectively. A positive voltage drop from the output of the current discriminator 9 (Fig. 3e) through time fc will go to the input of the current switch (Fig. 3, a), will switch TOJK 1 to the second output of switch 3 (Fig. 2), and conditions the current X switches the discriminator 9 of current 9 (FIG. 3), regardless of the voltage on the collector of the test transistor 4. Thus, the oscillation period T, set in the meter when the condition (1) is satisfied, is equal to T (FIG. 3) - and does not depend on the decay rate of the voltage on the collector of the tested transistor 4, when applied to eix) the base of the enabling current drop, t, e, from € If you disconnect the test transistor 4 from the circuit, then the oscillation period of the device will be equal to TQ 2bi, hook at the time of switching current 1 from the second output of switch 3 the current to the first sum of the currents I, (R. + R2) at the input of the discriminator 9 becomes greater than zero (Fig. 3, c) and a positive difference appears immediately at its output {Fig. 3, d, dashed line). According to this, measuring the period of the device oscillations with the test transistor 4 connected and disconnected with the help of indicator 2, one can determine the absorption time of the transistor V - o - ffo-) where T (-f) and Tf () is the period (often ta) device oscillations when transistor 4 is connected and disconnected, respectively. As a current discriminator 3 in the meter it is advisable to use a tunnel diode (TD) that provides high sensitivity and speed of the discriminator. The formula isobregenn time meter rassasyuan transistors; containing a pulse delay line connected to the nndvkator and a current switch, the output is coherently connected to the base of the test transistor, a power source connected through a reference resistor to the collector of the test transistor, characterized in that, in order to improve the measurement accuracy, an adjustable tchek source is inserted into it, a resistor and a current discriminator whose No.ixoa is connected to a delay line, and the input is connected to an adjustable current source and a second output of a current switch and to a test collector through a resistor th transistor. Sources of information taken into account in the examination 1.Stolrsky E, Measurements of parameters of transistors, M., Sovetskoye ras, 1976, p. 236. 2. USSR author's certificate number 48905O, cl. Q 01 R 31/26, 17.01,7a fw.I | I IG