SELECTIVE AMPLIFIER Russian patent published in 2012 - IPC H03F3/45 

FIELD: radio engineering.

SUBSTANCE: device has a first (15) additional resistor connected through alternating current between the output of the device (13) and the common power supply bus, wherein the base of the second (7) input transistor is connected to the output (13) of the device; the emitter of the second (7) output transistor is connected to the first (4) power supply bus through a second (16) current-stabilising two-terminal device and is connected through a series-connected second (17) additional resistor and a second (18) balancing capacitor to the emitter of the first (1) input transistor.

EFFECT: high Q-factor of the amplitude-frequency curve of the amplifier and its voltage gain at quasi-resonance frequency f₀.

3 cl, 7 dwg