OVERLOAD PROTECTIVE GEAR FOR POWER AMPLIFIER Russian patent published in 2003 - IPC

FIELD: radio communications engineering. SUBSTANCE: protective gear designed for protecting power amplifier input upon occurrence of overload and its output in case of short or open circuit in load has directional coupler 1 in feedback circuit of power amplifier 6 which is made in the form of two interlinked lines, input of first one being loaded into matching load of directional coupler 1, and output is connected to detector 3 whose output is connected to control unit 4. Input of second line of directional coupler 1 is connected to output of power amplifier 6 and its output, to load of power amplifier 6. Newly introduced in feedback circuit is bipolar transistor 5 whose base is connected to output of control unit 4 supplying base of bidirectional transistor 5 with dc voltage cutting off both junctions of bipolar transistor 5. Collector-emitter circuit of bipolar transistor 5 is, essentially, two-terminal network connected to conductor common for power amplifier 6 and feedback circuit and to input of power amplifier 6. Bipolar transistor 5 functions at the same time as self-controlled clipper of high-power input signals or noise and also as limiter in case of short or open circuit in load. EFFECT: enlarged functional capabilities of protective gear. 1 cl, 6 dwg