RU1804695C - Push-pull emitter follower - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase efficiency. The push-pull emitter follower comprises transistors 1, 2, a circuit of parallel connected biased diodes 3 and resistor 4, a current generator 5, and resistor 6. This results in galvanic isolation of the first and second transistors 1 and 2 and an increase in efficiency by decreasing the quiescent current. 1 ill.

Description

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The invention relates to radio engineering and can be used in automation devices, measuring equipment, radio engineering devices for various purposes.

The purpose of the invention is to increase efficiency.

The drawing shows a circuit diagram of a push-pull emitter repeater,

The push-pull emitter follower comprises first and second transistors 1 and 2, a biased diode 3, a first resistor 4, a current generator (CT) 5, a second resistor 6, power buses 7 and 8, power / input and output buses 9 and 10.

A push-pull emitter follower comprises first and second transistors 1 and 2, a biased diode 3, and a first resistor. 4, a current generator (GT) 5, a second resistor 6, power buses 7 and 8, input and output buses 9 and 10,

The push-pull emitter follower operates as follows.

In the absence of a signal, a potential is supplied to the base of transistor 1, which contains this transistor 1 in an initial conducting state.

The magnitude of the quiescent current flowing through transistor 2 and a circuit of parallel connected diodes 3 and resistor 4 is chosen such that the voltage drop across resistor 4 / whose nominal value is comparable in order of load rating / is the unlock voltage of diode 3, and the main part of the current quiescent flows through resistor 4. The quiescent current itself is determined by the voltage drop across resistor 6, which, in turn, is determined by the magnitude of the current generated by GT 5. Thus, the quiescent current of transistor 1 will be equal to the sum of the current generated th GT 5, and the quiescent current flowing through the transistor 2, diode 3 and resistor 4.

With an increase in the amplitude of the positive half-wave of the signal, the conductivity of transistor 1 increases, which leads to an increase in the current in its emitter circuit, while simultaneously causing a slight increase in the voltage drop across the mixed diode 3. The voltage drop across the biased base decreases by the same amount. the emitter junction of transistor 2. However, the locking of transistor 2 does not occur. in accordance with Kirchhoff’s law and in view of the constancy of the current generated by GT 5, along with a decrease in the base current of transistor 2 by the same amount, the current flowing through resistor 6 increases, which leads to an increase in the voltage drop across it and

prevents sharp locking of transistor 2.

. On the other hand, the decreasing base current of the transistor 2 will be at least an order of magnitude less than the increasing emitter current of the transistor 1 / tk. 1E / 1b /, therefore, the decreasing base current of the transistor 2 will not lead to any measurement of the operation mode of the transistor 1 and,

accordingly, it will not cause a change in the shape of the output signal.

With a decrease in the amplitude of the negative half-wave of the signal, the potential on the basis of transistor 1, and hence the potential at

its emitter is reduced. But on the same

the value decreases and the potential at the base

transistor 2, because transistor 1, resistor 6

and GTs form a level translator. If

the current set by GT 5 is selected by an order of magnitude greater than the maximum base current of transistor 2 at the maximum amplitude of the negative half-wave of the signal, then at the maximum baseline current of transistor 2, the voltage drop across resistor 2 will not decrease by such a value at which the current flows from emitter of transistor 1 through resistor 4 to the output of the circuit, does not change its

sign and does not become equal to zero. In this case, despite the locking of the diode 3. shunted by a small resistor 4, the potential at the emitter of transistor 1, and therefore, based on transistor 2

they do not change, as a result of which distortions are reduced and efficiency is increased, since in the claimed circuit, when the current decreases, the maximum current generated in the load does not decrease. In this case, the value

The efficiency of the proposed circuit is characteristic of push-pull circuits operating in AB mode.

Claims (1)

SUMMARY OF THE INVENTION A push-pull emitter follower containing first and second transistors, including a common collector and having a different structure, a voltage divider, the first output of which is connected to the emitter of the first, the second output to the collector of the second, the tap to the base of the second transistor, the first a resistor, the first output of which is connected to the emitter of the first transistor, the base of which is the input, and the second output of the first resistor is the output of the push-pull emitter follower, characterized in that, in order to increase efficiency, parallel to the first resistor a mixed diode is introduced, the voltage divider is made on series-connected between it the first and second terminals of the second coupling, wherein the emitter of the second transistor and the current generator, the connection point is connected to the second terminal of the first one is a tap of a voltage divider divider.