DIFFERENTIAL AMPLIFIER WITH CONTROLLED GAIN Russian patent published in 2010 - IPC H03F3/45 H03G3/30 

FIELD: physics, radio.

SUBSTANCE: invention relates to radio engineering and communication and can be used in automatic gain control devices, phase detectors and modulators, in phase-locked loop and frequency multiplication systems or as an amplifier whose voltage transfer ratio depends on the control signal level. The controlled amplifier is the basic block of modern systems for receiving and processing high-frequency and microwave signals, and analogue computer and measurement equipment. The differential amplifier (DA) has first (1) and second (2) input transistors (T), whose emitters are connected to each other through anti-parallel connected first (3) and second (4) p-n junctions and connected to the first (5) and second (6) reference current sources, a load circuit (7) connected to collectors of the first (1) and second (2) input T, a third reference current source (8) connected to the common point of anti-parallel connected first (3) and second (4) p-n junctions. The circuit has a first (11) and a second (12) control T, whose bases are connected to the control input (13) of the DA, combined collectors are connected to the third reference current source (8), the emitter of the first (11) control T is connected to the emitter of the first (1) input T, and the emitter of the second (12) control T is connected to the emitter of the second (2) input T.

EFFECT: increased suppression ratio of the control signal.

3 cl, 11 dwg