SU468350A1 - Amplifier - Google Patents

Description

one

The invention relates to radio engineering and can be used in the output stages of radio transmitting devices.

A power amplifier is known that contains P stages on transistors connected according to a common base circuit, the collectors of which are connected to a common load, and its other end is connected to a common bus through a power source.

However, in a known amplifier, it is not possible to balance the operating mode of the transistors when the amplifier stages are connected in parallel,

The aim of the invention is to ensure the identity of the operation modes of the transistors.

j To do this, two winding transformers are introduced into the amplifier, with the emitter of the transistor of each amplifier stage connected to the beginning of the primary winding of the corresponding transformer, the beginning of the secondary windings of all transformers connected to the common bus, and the end of the primary winding of the first stage transformer is connected via an input signal source. with the end i of the secondary winding of the U-cascade transformer and with a common bus, the secondary winding of the corresponding transformer of each cascade, except the last, is connected to the primary winding of the transformer of the next cascade.

The drawing shows an amplifier circuit. The amplifier contains parallel connections

Transistors 1-4, which are located in collectors and bases. To the common point of connection of their collectors through the load 5 to "; source of power 6 amplifier. To the emitters of transistors 1-4 are connected

Responsibly the beginnings of the primary windings of transformers 7 - 10. The beginnings of the secondary windings of these transformers are connected to the common busbar of the power source 6. The end of the primary winding of the transformer

7 of the transistor 1 is connected via an input source 11 to the end of the secondary winding of the transformer 1O of the last transistor 4. The ends of the secondary windings of the remaining transformers 7-9 are connected respectively to the ends of the primary

windings of transformers 8 - 10. The connection point of the secondary winding of the transformer 10 of the last transistor 4 and the source of the input signal 11 is connected to the common power supply bus 6,

By high frequency, the input impedances of the common amplifier stages, representing the input source voltage, are connected to its circuit in series and the apparent load resistance of the exciter is equal to the sum of the input resistors of the transistors.

The implementation of transformers (double winding) creates isolation of all cascades at fiOcTOHHHOMy current and, by means of a series connection of input circuits at high frequency, equalizes the emitter currents (excitation currents) of all stages of amplification. Since, in amplifiers with a common base, the collector current is determined by the current

Buses (minus 3–10% of the base current, then in the proposed amplifier, the operation modes of the transistors are completely identical, since with equal voltage currents across the parallel-connected collectors of the transistors, they are also equal.

Subject invention

An amplifier containing Q. cascades on transistors connected according to a common base circuit, the collectors of which are connected to a common load, and its other end is connected to a common length through a power source, in order to ensure the identity of transistors operating modes, Two-winding transformers are introduced into it, and the emitter of the transistor of each amplifier stage is connected to the beginning of the primary winding of the corresponding transformer, the beginning of the secondary windings of all transformers are connected to the common bus, and the end The primary winding of the transformer of the first cascade is connected via an input source to the end of the secondary winding of the fl-ro cascade transformer and to the bus;

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