SU364071A1 - AMPLIFIER - Google Patents

Description

The invention relates to the field of radio engineering and can be used in linear circuits of analog devices, operational amplifiers and comparators. The purpose of the invention is to provide minimal non-linear distortions in the output signal and an increase in output power. The goal is achieved by the introduction of an additional cascade performed on two transistors of one conductivity connected in a sequence of direct current, the emitter of one of which and the collector of the other is connected to the base of the transistor of the opposite type of conductivity of the output transistor of the cascade with the collector of the transistor cascade of the voltage amplification, and the base of the other transistor - with the base of the transistor of the voltage cascade. FIG. 1 is a circuit diagram of a power amplifier; in fig. 2 shows oscillograms of input and output voltages. The power amplifier contains an emitter follower on the input of transistor 1, parallel to the transition the base-emitter of which includes a resistor 2. The collector of transistor 1 is connected to the positive pole of the power source through a resistor 3, and the emitter is connected to a negative pole; In addition, the bases of transistor 5 voltage amplifier and transistor 6 of an additional stage are connected to the emitter of the transistor /. The collector of the transistor 5 through the base-emitter junction of the transistor 7 of the additional stage is connected to the collector of the transistor 6 and the base of the output transistor 8 of conduction, inverse to the conductivity of the remaining transistors. The emitter of transistor 5 and the collector of transistor 8 are connected to the negative pole of the power source. The collector of the transistor 5 is connected via a series-connected diode 9 connected in the forward direction, and the resistor 10 is connected to the positive pole of the power source. The collector of transistor 7 and the collector of another output transistor 11, the emitter of which is connected to the collector of transistor 1 and to the emitter of transistor 8, are also connected here. The base of transistor 11 is connected to the junction point of diode 9 and resistor W as follows. The amplified signal is applied to the base of the transistor /, which provides a high input impedance. Transistor 1 operates according to the emitter follower circuit, therefore its gain does not exceed unity. From the emitter of transistor 1, the signal is removed to the base of transistor 5. The signal amplified in antiphase from the load resistor to is removed to the base of transistor 11, which operates according to the emitter follower circuit and is a power amplifier. In addition, the signal is removed from the collector of transistor 5 to the base of transistor 7 of the additional stage, and from the base of transistor 5, the signal in phase simultaneously arrives at the base of transistor 6 of the additional stage. The signal amplified at the additional stage is removed from the point of connection of the emitter of transistor 7 and collector of transistor 6 to the base of transistor 8 of the output stage, which operates according to the emitter follower circuit and is a power amplifier. The inclusion of an additional cascade of transistors 6 and 7 in the base circuit of transistor 8 creates the same power gain in each arm of the output stage (Fig. 2), which ensures the symmetry of the output signal with a small load and increases the output power.

Subject invention

A power amplifier with transistors containing a series-connected input emitter follower, a voltage amplification cascade, made on a transistor connected in accordance with a circuit with a common emitter, an output stage on two transistors of different conductivity connected in series

DC, characterized in that, in order to ensure minimal non-linear distortions in the output signal and increase the output power, an additional cascade is introduced, performed on two transistors of the same conductivity connected in series by DC, the emitter of one of which and the collector of the other with the base transistor of the opposite conductivity type of said output

the cascade, while the base of one transistor of the additional cascade is connected to the collector of the transistor of the cascade of voltage amplification, and the base of the other transistor is connected to the base of the transistor of the cascade of amplification by voltage.

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