Television tuner for common use in BS/UV

摘要

PCT No. PCT/JP88/01313 Sec. 371 Date Aug. 14, 1989 Sec. 102(e) Date Aug. 14, 1989 PCT Filed Dec. 23, 1988 PCT Pub. No. WO89/06072 PCT Pub. Date Jun. 29, 1989.The invention relates to a television receiving tuner for receiving television signals of VHF band/UHF band, a CATV signal, and a satellite television broadcasting signal. As a circuit for receiving the television signals of the VHF band/UHF band and the CATV signal as a first input signal, there is provided a double super type tuner of the up/down converter system including a first local oscillator (6) and a first mixer (5) which construct an up converter and a second local oscillator (10) and a second mixer (9) which construct a down converter. When the satellite television broadcasting signal as a second input signal is received, the first local oscillator (6) and the first mixer (5) in the up converter section are switched by switching circuits (12, 13) and used as a down converter. At least the first local oscillator (6) and the first mixer (5) are commonly used both for reception of the television signals of the VHF band/UHF band and the CATV signal and for reception of the satellite television broadcasting signal, thereby accomplishing the simplification of the construction and the low costs.