PURPOSE: To simplify the construction, to balance routes and to reject distortion, by driving an active element group forming two signal routes respectively with a common bias circuit, in a demodulation circuit of phase difference branching device constitution.
CONSTITUTION: A signal component P for broadcast program is processed with the 1st route of transistors (TRs)411, 412 located closely and the 2nd route of TRs413, 414. Carrier signals C1, C2 are respectively applied to the base of the TRs412, 414 to be a voltage level which can be turned on/off. Thus, at an active region determined with the voltage of the carrier signals C1, C2, the class A bias operation can be made. Since two signal toutes are operated with a common bias, the TRs411, 413 or 412, 414 can be made to a chip. Since carrier signals C1', C2' with phase inversion are added to two objective signal routes, the TRs441, 442 can only respond to the carrier signal component allowing to simplify the construction.
OOTSUKI TSUGUO
SATOU KAZUO
TAKEKOSHI YOSHIO
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