CONTROLLED AC AMPLIFIER Russian patent published in 2010 - IPC H03F3/45 H03G3/30 

FIELD: radio engineering.

SUBSTANCE: invention may be used as AC amplifier, coefficient of transmission by voltage of which (K_u) depends on the level of control signal (u_y). Such devices are used in structure of analogue microchips of various functional purpose, systems of automatic amplification control, analogue signal multipliers, etc. Controlled AC amplifier (CACA) comprises the first (1) input transistor (T), base of which is connected to the main (2) input of CACA, the second (3) input T, base of which is connected to control inlet (4) of CACA, dipole (5) of local negative feedback (NFB) connected between emitters of the first (1) and second (3) T, load circuit (6) connected to collector of the first (1) and second (3) T and outlet (7) of CACA, the first (8) blocking capacitor (C) connected by alternating current between emitter of the first (1) T and common bus (9) of supply sources (SS), the first (10) current stabiliser connected to emitter of the first (1) T, the second (11) current stabiliser connected to emitter of the second (3) T, the second blocking C (12). The circuit comprises the first (13) and second (14) additional T, emitters of which are connected to each other via additional dipole (15) of NFB and are connected to according first (16) and second (17) current stabilizers, base of the first (13) additional T is connected to control input (4) of CACA, the base of the second (14) additional transistor is connected to common bus (9) of SS, besides between combined collectors of the first (13) and second (14) T and combined collectors of the first (1) and second (3) T there is additional inverting current repeater (18) connected, and emitter of the second (14) T is connected to the first input of the second (12) blocking C, the second output of which is connected by alternating current to common bus (9) of SS.

EFFECT: improved ratio of control signal suppression in wide range of frequencies.

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