SU1569942A1 - Differential amplifier - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to reduce the consumed current while maintaining speed. With the common-mode shift of the inputs of the differential amplifier in the negative direction and with a more negative voltage at the bases of the first 1 and third 3 transistors relative to the bases of the second 2 and fourth 4 transistors, the currents of the second 2, third 3 and sixth 6 transistors increase, and the currents of the first 1 decrease, the fourth 4 and the fifth 5 transistors. The output current of the second controlled current source 11 is limited only by the resistance of the first 8 and second 9 resistors, which ensures the operability of the differential amplifier at a high rate of change in common-mode voltage. 1 il.

Description

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The invention relates to radio engineering and can be used to convert a differential signal into a push pull.

The purpose of the invention is to reduce the consumed current while maintaining speed.

The drawing shows a circuit diagram of a differential amplifier (DU)

The control contains the first 1 and second 2 transistors pn-type, the third 3 and the fourth 4 transistors pnp-type, the fifth 5th and sixth b transistors np-p-type, the seventh transistor 7 pnp -type, first 8 and second 9 resistors, first 10 and second 11 controlled current sources, bias source 12 and current supply element 30

The remote control works as follows. At the common-mode offset of the remote control inputs in the negative direction and with a more negative voltage at the bases of the first 1 and third 3 transistors relative to the bases of the second 2 and fourth 4 transistors, the collector currents of the second 2, third 3 and sixth b transistors increase and the collector currents of the first 1, fourth 4, and fifth 5 transistors. As a result, the current entering the input of the first controlled current source 10 decreases, and the current entering the input of the second control increases. 11 for example. With large differential input signals, the output current of the first controlled current source 10 becomes zero, while the bias diode 12 and the seventh transistor 7 are shifted by pure capacitive currents. At the same time, the output current of the second controlled current source 11 is limited only the resistance of the first 8 and second 9 resistors and can take a theoretically unlimited value, which determines the efficiency of the remote control at a high rate of change in the common-mode voltage in the negative direction appear ,.

When changing the signs of the common-mode and differential voltages, the collector currents of the first 1, fourth 4 and fifth 5 transistors increase, and the collector currents of the second 2 third 3 and sixth 6 transistors decrease. An increase in the collector current of the nth transistor 5 leads to

increasing the output current of the first controlled current source 10, while providing a significant increase in the limit increase rate of the voltage at the outputs of the feedback circuit in the positive direction for the same value of its initial current bias (the feedback feedback circuit is formed by the fifth , sixth 6 and seventh 7 transistors and bias source 12) In this case, the initial bias current of the servo feedback and, accordingly, the entire amplifier as a whole can be significantly reduced while maintaining its speed action „

When a 10-30 pF capacitor is switched on between the outputs of the first 10 and second 11 controlled current sources, the speed provided by the proposed remote control additionally increases by a factor of 3–5 with a constant current consumption,

Claims (1)

Invention Formula , Q 5 0 five A differential amplifier containing the first and second npn-type transistors, the bases of which are combined with the bases of the third and fourth transistors of the pnp-type, respectively, the fifth and sixth transistors of pnp-type, the emitters of which are connected respectively to the collectors of the first and second transistors, as well as through the first and second resistors - with the emitters of the fourth and third transistors, respectively, the bases of the fifth and sixth transistors are connected to the output of the first controlled current source, the common terminal of which is connected to the first the power supply bus, the output of the first controlled current source through the bias source is connected to the emitter of the seventh pnp type transistor, the collector of which is connected to the second power bus, and the base to the emitters of the first and second transistors and to the output of the second controlled current source the input of which is connected to the collector of the fourth transistor and the first output of the current supplying element, and the common terminal is connected to the second power supply bus, and the collector of the fifth transistor is connected to the first bus PI 515099426 via the load element The second ii npnod of the gokasadal torl is connected to. the input of the first control element is equal to the equal current thread, and the contact is so that, in order to reduce the consumer of the third transistor through the electric current while maintaining the momentum the load is connected to the second shimennisty, the collector of the sixth trans-feed 0