SU1716597A1 - Amplifier - Google Patents

Abstract

The invention relates to power amplifiers and can be used in radio engineering and communications. The purpose of the invention is to increase the output power at a relatively low voltage of the power source. By introducing successive RC taps between the output of the device and the emitter of the transistor of each arm of the pre-exit push-pull cascade, the goal is achieved. 1 il.

Description

The invention relates to a power amplification technique and can be used in radio engineering and communications.

The purpose of the invention is to increase the output power.

The drawing shows a circuit diagram of the amplifier.

The amplifier contains an input phase-inverted cascade 1 with a split load, performed on the first 2 and second 3 differential stages, containing transistors 4-7, resistors 9-12, transistors 13 and 14 of the two-stage push-pull stage 15, transistors 16 and 17 of the output two-stroke cascade 18 , load 19, a common negative feedback circuit resistor 20, resistors 21 and, 22, successive RC circuits 23 and 24. performed on capacitors 25 and 26, resistors 27 and 28.

The amplifier works as follows. zom.

The input signal is fed to the input and then through the coupling capacitor to the bases of transistors 4 and 6 differential stages 2 and 3. Since the input amplifier stage 1 operates in a phase-inverse mode, the current of the transistor 4 increases when the negative half-wave increases. increasing the positive half-wave of the signal increases the collector current, the transistor 6. The alternating increase in the currents of the transistors 4 and 6 leads to the corresponding alternate opening of the transistors 13 and 14, as this will increase The voltage drops across the resistors 9 and 11, to which the bases of the transistors 13 and 14 of the pre-exit push-pull cascade are connected. When transistor 13 or 14 is opened, the base terminals of transistors 16 and 17 will alternately be connected through resistors 21 and 22 either to the negative or to the positive power line, which will lead to alternate opening of the transistors 16 and 17. In the absence of serial RC circuits 23 in the circuit and 24 the degree of opening of the transistors 16 and 17 will be the greater, the greater the current in the pre-exit push-pull stage 15 and the lower the resistance of resistors 21 and 22, Full opening of the transistor 16 can be achieved only if the voltage and its base will be more negative than on the collector, and transistor 17 - with a more positive on the base in relation to the collector. Thus, in the absence of the mentioned RC circuits, the complete

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ABOUT

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Closing transistors 16 and 17 is impossible, and an attempt to increase the current of the pre-output stage leads to a decrease in the efficiency of the amplifier.

If the circuit has serial RC circuits 23 and 24 and no signal at the input, capacitors 25 and 26 are each charged to half the supply voltage, and the total voltage on the two capacitors is close to the supply voltage. When a positive half-wave signal is present at the input of the amplifier, transistors 14 and 17 are opened and capacitor 26 is discharged through the open transistor 17, resistors 22 and 28, and capacitor 25 is charged almost to the full supply voltage. When capacitor 26 is discharged at resistor 22, an additional voltage is formed, the positive potential of which will be located at the emitter of transistor 14, and negative at the power supply bus, and this leads to an increase in the positive voltage at the base of transistor 17 and contributes to its fuller opening. In addition, this additional voltage contributes to a more complete opening of transistor 14, since its positive potential is applied to the emitter of transistor 14, which also contributes to a more complete opening of transistor 17. Similarly, transistors 13 and 16 work in the presence of a negative half-wave signal at the input booster.

Thus, switching on the successive RC circuits 23 and 24 makes it possible to increase the output power of the amplifier while reducing the operating current of the pre-output stage, with the result that the efficiency of the amplifier becomes close to the maximum possible.

FORUMAWLAH AND ISLANDS

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An amplifier covered by a common negative feedback circuit and containing a series-connected input-phase inverted cascade with a split load, performed on two differential stages, a pre-exit and an output push-pull stages, performed on transistors of the opposite structure, while the pre-exit two-stroke transistors are connected in a circuit with a common emitter with resistors in the emitter circuits, the transistors of the output push-pull stage are connected according to the circuit with a common collector, the junction point is Itter transistors which is the output of the amplifier, and between the bases of the transistors included bias circuit, characterized in that, in order to increase power output, between the output of a push-pull output stage and the emitters of transistors push-pull stage proximity with each arm administered sequentially RC-chain.

Claims (1)

Claim I The amplifier is covered by a common negative feedback circuit and contains a series-connected input phase-inverse stage with a divided load, made on two differential stages, output and push-pull stages, made on transistors of the opposite structure, while the transistors of the output terminal push-pull stage are connected according to the scheme with a common emitter with resistors in the circuits of the emitters, transistors of the output push-pull stage are connected according to the scheme with a common collector, the connection point is emitt of transistors of which is the output of the amplifier, and a bias circuit is connected between the bases of the transistors, characterized in that, in order to increase the output power, a serial RC circuit is introduced between the output of the output push-pull cascade and the emitters of the transistors of the output push-pull cascade of each arm.