SU430481A1 - TWO-TIME AMPLIFIER - Google Patents

Description

one

The present invention relates to the field of radio engineering and relates to push-pull amplifiers.

Known push-pull amplifiers, and made on transistors of different conductivity types, connected according to the scheme with a common collector, containing an additional transistor.

An inventive aspect is to protect the amplifier against overloads.

This is achieved by connecting into the collector one of the transistors of a resistor shunted by a chain of a second resistor connected in series to an additional transistor, the base of which is connected to the amplifier output through the kendensator, and the third resistor and diode to the base and collector of the mentioned transistor push pull.

Pa drawing presents on the scheme of the proposed amplifier.

The amplifier has 2 input and / and output terminals, main transistors 5 and 4, additional transistor 5, diode 6, resistors 7-11, capacitor 12 n terminals 13, 14 (poles) of the power supply.

In the static mode, the collector (or emitting) currents of the main transistors 3 n 4 are equal and correspond to the quiescent current. The quiescent current is shorted to the power source (terminal} o) through a resistor 10, through which also the current flows from the series-connected diode 6 and resistor 9. This same current creates a voltage drop across the resistor 7, corresponding to the bias voltage at the fundamental shifting transitions transistors

3 4.

The stabilization of the quiescent current of the 3 n 4 transistors is provided as follows. With

As the ambient temperature increases, the increase in the quiescent current causes an increase in the voltage drop across the resistor 10, the resistance on the resistor 9 decreases, and the current through it decreases. As a result, the voltage drop across resistor 7 is reduced, thus autocompensating for a change in the current of the main transistors 5 and 4 is achieved. In static mode, the auxiliary transistor 5 is closed by a voltage drop of direct current on diode 6.

In d1P1amic mode with the maximum input signal, which is supplied between terminals / and 14, the main transistors are operational and are alternated with the initial mixture. With

the work of the upper arm usi.: 11gge.t traizistor

4 is disconnected and transistor 3 opens. The current of the main transistor 3 increases, and a voltage appears at the output of the amplifier (terminal 2). With this potential

o6nj.eii the points of diode 6 and resistor 10 with respect to the terminal 13 one hundred “are more negative, and the potential of the common point of diode 6 and resistor 9 is more positive. As a result, the voltage on the diode 6 changes polarity (compared to the static mode), the diode 6 closes, and the additional transistor 5 opens and passes current to the power supply (terminal 13).

When the output is short-circuited in the dynamic mode, the control voltage from the amplifier output to the base of the additional transistor 5 (through the capacitor / 2) does not flow, so it does not open, and the collector current of the main transistor 3 passes through the resistor 10. The voltage drop across the resistor 10 increases and as the resistor 9 decreases sharply, the bias voltage across the resistor 7 therefore decreases, the main transistors 3 4 are closed and the capacitor 12 is charged for some time in this state.

Resistors 8 and 11 are included to reduce non-linear distortion of the Z-SILITEL.

The subject of the invention. A push-pull transistor amplifier of a different type of conductivity, connected according to a common-collector circuit, characterized by

so that, in order to protect the amplifier from overload, the collector of one of the push-pull amplifier transistors | A resistor is switched on, squeezed by a chain of series-connected second resistor and an additional transistor, the base of which is connected through the capacitor to the decoder and This push-pull amplifier transistor is respectively via a third resistor and a diode.