SELECTIVE AMPLIFIER Russian patent published in 2013 - IPC H03F3/00 

FIELD: radio engineering, communication.

SUBSTANCE: amplifier comprises a source of a signal (1), connected with an inlet of a device (2), the first (3) input transistor, the emitter of which via the first (4) current-stabilising dipole is connected with the first (5) bus of a power supply source, and the collector is connected to the second (6) bus of the power supply source, the second (7) input transistor, the base of which is connected with the inlet of the device (2), the collector is connected with the second (6) bus of the power supply source via the first (8) frequency-setting resistor and is connected with the outlet of the device (9). Between the emitter of the second (7) input transistor and the first outlet of the second (10) current-stabilising dipole there is a straight-shifted p-n transition (12) connected, the first output of the second (10) current-stabilising dipole is connected with the emitter of the first (3) input transistor via serially connected the first (11) correcting capacitor and the second (13) frequency-setting resistor, and is connected with the base of an additional transistor (14), the collector of which is connected to the second (6) bus of the power supply source, and the emitter via the third (15) current-stabilising dipole is connected with the first (5) bus of the power supply source and is connected with the emitter of the second (7) input transistor via a dividing capacitor (16), besides, the output of the device (9) is connected with the base of the first (3) input transistor and is shunted by AC with the second (17) correcting capacitor.

EFFECT: higher quality of amplifier amplitude-frequency characteristic and its amplification ratio by voltage at quasi-resonance frequency f₀.

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