SU1334357A1 - Power amplifier - Google Patents

Abstract

The invention relates to radio engineering and provides an extension of the frequency range to the high frequency (HF) region and an increase in the linearity of the transmission coefficient. The amplifier (U) contains an input stage 1, a pre-output stage 2, an output stage 3, feedback resistors 19 and 20, a mid-point power source 21, an additional power source 22 and a load 23. Cascade 1 is made of transistors (T) 4 and 5, a current generator 6, a load resistor 7, and a resistor 8. Cascade 2 is provided at T 9-11, the current providing element 12, the bias voltage sources 13 and 14. Cascade 3 is made on field T 15 and 16 and offset resistors 17 and 18. Reducing the propagation time of signals in the feedback loop allows U with field T 15 and 16 in cascade 3 to expand the ranges of amplified frequencies in the RF region and increase linearity, 1 or about (L

Description

The invention relates to radio engineering and can be used in radio engineering devices for various purposes.

The purpose of the invention is to expand the frequency range to high frequencies and increase the linearity of the transmission coefficient.

The drawing shows a circuit diagram of a power amplifier.

The power amplifier contains an input stage 1, a terminal output stage 2, an output stage 3. The input stage 1 is made on the first and second transistors 4 and 5, a current generator 6, a load resistor 7, a resistor 8. The pre-output stage 2 is made on the first and second transistors. 9 and 10 and the auxiliary transistor 11, the current driver element 12, the first and second bias sources 13 and 14. The output stage 3 is provided on the first and second field effect transistors 15 and 16, the bias resistors 17 and 18. The amplifier also contains first and second feedback resistors 19 and 20, a mid-point power supply 21, an additional power supply 22, a load 23.

The power amplifier works as follows.

The amplified signal is supplied relative to the common bus power amplifier to the base of the first transistor 4 of the input stage 1, which plays the role of the emitter follower. Next, the signal from the emitter of the first transistor 4 is fed to the base of the second transistor 5, connected according to the scheme with a common emitter. This transistor produces the main amplification of the input stage 1. The signal voltage amplified by the input stage 1 is removed from the load resistor 7 and fed to the input of the pre-output stage 2 - to the base of the first transistor 9 which, by amplifying the input current, the signal produces approximately the same emitter currents and collector. I

These currents are closed through the emitter-base transitions of the second and additional transistors 10 and 11, which have a very low input resistance. Since the bases of the second and additional transistors 10 and 11 from the first and second sources 13 and 14 of the bias voltage with

the voltages supporting these transistors in active mode are responsibly supplied, the emitter currents of the transistors are almost completely transmitted to the collector circuits of the transistors, where they, creating antiphase voltage drops across the bias resistors 17 and 18

and second field-effect transistors 15 and 16. an output stage 3 operating in mode B (or AB), which is determined by the value of the cut-off voltage of the first and second field

the transistors 15 and 16, the magnitude of the resistors 17 and 18, the bias, the magnitude of the voltage of the first source 13, the bias voltage and the magnitude of the current-setting element 12.

From the output stage 3, which is simultaneously the output of the power amplifier, the signal goes to the load 23 and through the first feedback resistor 19 to the connection point of the second feedback resistor 20 and the emitter of the second transistor 5. Selection of the values of the first and second resistors 19 and 20 feedback sets the gain

power amplifier.

Since the values of the first and second feedback resistors 19 and 20 can be chosen sufficiently small and taking into account that the second transistor: the torus 5 for the feedback signal operates in a common base circuit and the first transistor 9 of the pre-output stage 2 is loaded on low-impedance input resistances Additional and second transistors 11 and 10, as well; However, the fact that these transistors operate in a common base mode, the propagation delay of the signals in the feedback loop becomes minimal.

Reducing the propagation time of the signals in the feedback loop allows the power amplifier with field-effect transistors in the output stage 3 to expand the ranges of amplified frequencies to high frequencies and increase linearity.

Claims (1)

Invention Formula 55 A power amplifier containing an output cascade made in a push-pull circuit on the first and second field-effect transistors having the same structure, parallel to the gate-source transitions of which the corresponding bias resistors are included, the drain of the first and the source of the second field-effect transistors respectively and a second power supply bus with a midpoint connected to a common bus, and an additional power supply, the first bus of which is connected to the second bus power supply with a midpoint, as well as a pre-output cascade made on the first and second transistors having one structure, the emitters of which are connected and connected via a current-supplying element to the second bus of an additional power source, the collector of the second transistor of the pre-output cascade connected to the gate of the second field-effect transistor , the structure of the second transistor of the input stage is opposite to the structure of the first transistor of the pre-output stage, the collector of the second transistor of the input the cascade is connected to the base of the first transistor of the pre-output cascade and through the load resistor to the second bus of the additional power source, as well as the first feedback resistor connected by one output to the combined drain and source I.China editor I.Kasarda I.Popovich Corrector A.T. Order 3979/56 Circulation 901 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 five 0 five 0 second and second field-effect transistors, and a second feedback resistor, connected by a single output to a common bus, characterized in that, from expanding the frequency range to high frequencies and increasing the linearity of the transfer coefficient, the base of the first transistor of the input stage is The input of the power amplifier, the emitter of the first and the base of the second transistors of the input stage are connected and through the input current generator are connected to the second power supply bus with a midpoint, to the first bus of which the collector of the first is connected the input stage transistor, the other terminals of the first and second feedback resistors are connected and connected to the emitter of the second transistor of the input stage, the emitter-collector of the additional transistor having the structure of the second transistor of the pre-output cascade is inserted between the collector of the first transistor of the output transistor which through the input the first source of bias voltage, and the base of the additional transistor through the input of the second voltage source bias neither, are connected to the second pshne additional power source.