GB1445510A - Amplifier circuit - Google Patents

Abstract

1445510 Amplifiers NIPPON ELECTRIC CO Ltd 8 Aug 1974 [9 Aug 1973] 35032/74 Heading H3T An amplifier circuit includes first and second hybrid circuits 101, 102 respectively, each having a pair of signal inputs 31, 34 and 35, 38 respectively and a pair of signal outputs 32, 33 and 36, 37 respectively in conjugate relationship, wherein a signal applied to a signal input is divided into two components having a phase difference of 90 degrees, the two components being coupled to respective ones of the outputs. First and second amplifiers 1, 2 are connected respectively between the first output 32 of the first hybrid circuit and the first input 35 of the second hybrid circuit and between the second output 33 of the first hybrid circuit and second input 38 of the second hybrid circuit, and feedback means 11 connects the second output 37 of the second hybrid circuit to the second input 34 of the first hybrid circuit. In an embodiment, each amplifier comprises a transistor in common emitter connection, while the hybrid circuits may be #/4 distributed directional couplers, branch line directional couplers or directional couplers of slot-coupling type. The feedback path may comprise a cable, or alternatively an isolator (Fig. 6, not shown) or an attenuator (Fig. 7, not shown) which serves to stabilize the circuit. The Specification demonstrates that the overall gain is as if the amplifiers were connected in cascade, but the output power as if they were in parallel. The amplifiers used in the arrangement may themselves be of the same type (Fig. 5, not shown).