| 摘要 |
PURPOSE:To make a television tuner or the like small-sized by combining grounded-base oscillators and operating one as a mixing circuit when the other is in the oscillating state. CONSTITUTION:Oscillating circuits Sa and Sb have bases grounded, and the former is a VHF oscillating circuit, and the latter is a UHF oscillating circuit. Bases of transistors TRs 11a and 11b constituting these oscillating circuits are connected directly. When a VHF signal is inputted to an input line 20a, the TR11a is oscillated but the TR11b stops oscillation. Then, the oscillating circuit Sb is operated as a mixing circuit, and an IF signal is outputted from an output line 21a. When a UHF signal is inputted to an input line 20b, the TR11b is oscillated but the TR11a stops oscillation. Then, the IF signal is outputted from an output line 21b similarly. Consequently, the television tuner or the like is made small-sized. |
