SU394915A1 - AMPLIFIER - Google Patents

Description

one

This invention relates to the field of radio engineering.

Power amplifiers with a transformer current and an rt-th number of power sources are known, which are designed in a push-pull pattern on transceivers in each arm.

However, the known amplifiers do not have sufficiently large output power.

In order to increase the output power, the base of each subsequent transistor of the proposed amplifier is successively connected to the additional secondary winding of the input transformer and a diode connected to the emitter of the previous transistor.

The drawing shows the scheme of the proposed power amplifier.

The amplifier is a push-pull cascade, each arm of which contains n series-connected traisistors. Calad push pull pair of transistors TI-TI, TZ-TZ, ... T „-G, / is connected to its series-connected power source through diodes, ...

D “-D.

The load of the amplifier is included in the emitters of the Ti-T / transistors.

An input transformer Tp, having one primary winding, and 2n-secondary, wound 2d-filing is used for excitation. Moreover, the field windings to the transistors T and TI are connected through resistors RQ and RO directly to the base and the emitter, respectively, of the transistors TI and

T /.

The excitation circuit of the subsequent transistors is made differently: for the remaining secondary windings, one end is connected to the base of the corresponding transistors, and the other end

through diodes Д "and Д, /, which provide protection of base circuits against reverse overvoltages, to the emitter of the previous transistor, from the load.

In the initial state, all transistors are closed, and the emitter-collector voltage of each transistor does not

, E, ... „

exceeds the value - where

EI, E2 ... E ,, is the voltage of the respective power sources, and n is the number of sources.

If there is a variation in the resistances of the locked transistors, the presence of diodes eliminates the possibility of transferring the collector to the collector-emitter section.

With the appearance and growth of the input signal on the windings Wi, W ... W,, the signal voltage of the same amplitude is induced. However, increasing the input signal leads

to the appearance of the base current only transistor

TI across the circuit: the base of the transistor Ti is the resistor / 6- transition emitter-base of the transistor T /.

The base currents of the remaining transistors are absent, since their circuits include the resistance of the collector-emitter section of the previous transistor (counting from the load).

The operation of one arm of the amplifier occurs as follows (the other works well in the same way).

With an increase in the input power, only the transistor Tj, which operates in active mode, opens. Through the load shoulder current flows from the EI source along the circuit: diode D - collector-emitter of the transistor TI - load.

With the approach of the transistor TI to the saturation mode, the resistance of the collector section is reduced, which ensures the flow of the base current of the transistor Td.

As soon as the dynamic component of the collector-emitter transistor T. becomes equal to the resistance Re, then the base oxides of the transistors T and T2 become the same, therefore, their collector currents are also equal. The collector of the transistor T2 at the time the transistor Ti reaches the saturation mode abruptly reaches the value of the collector current of the transistor T.

A further increase in the input signal leads to a synchronous increase in the collector currents of the transistors T and Td, with the transistor Ta operating in the active mode and the transistor T in the saturation mode. The current through one side of the load flows already from two series-connected sources of EI + 2 but the circuit: diode C - collector of transistors T2 and TI - shoulder of the load.

Since the voltage on the load, age, becomes greater than EI, the diode D1 turns off.

When the transistor T2 approaches the saturation mode, the resistance of the collector section of the transistor TZ decreases, allowing the base current of the transistor Tz to flow. After the transistor T2 reaches the state close to saturation, the current of the transistor Tz abruptly reaches the value of the current of transistor T2, the process proceeds in a similar way.

With a decrease in the input signal, the process proceeds in reverse order. The voltages of each of the power supply elements are chosen based on the condition of providing a uniform power dissipation on each of the transistors.

Present Invention

Power amplifier with transformer input and l-th number of power sources, made on transistors one

conduction on the push-pull circuit, containing in each arm / gth number of transistors connected in series with direct current, with the base of the first transistor of each arm connected to the emitter

This transistor through a series-connected resistor and the secondary winding of the input transformer is distinguished by the fact that, in order to increase the output power, the base of each subsequent transistor is connected via a series-connected secondary winding of the input transformer and a diode to the emlter of the previous transistor.

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