Coupling circuit for electronic tuner

Abstract

Abstract PURPOSE:To ensure a broader reception channel and the S/N with an excellent tuner and to realize a small sized tuning coil by adding a varactor diode having a large capacitance change ratio to a conventional electronic tuner coupling circuit so as to combine the two diodes in parallel. CONSTITUTION:Varactor diodes 37-40 having a large capacitance change ratio are combined in parallel with coupling varactor diodes 5, 13, 16, 31 with large capacitance change ratio and the parallel connection is connected to an input terminal of transistors(TRs) 9, 20, 26 being semiconductors via coupling capacitors 8, 10, 19, 27 respectively. Then the same or different kind of tuning varactor diodes 6, 12, 17, 32 are connected also to constitute the tuning circuit. Thus, the matching between the tuning circuit and a transistor section is improved, the loss in the input circuit and the inter-stage circuit is reduced remarkably, the oscillation is made stable and the oscillation power is improved in the oscillator circuit so as to improve the gain and NF remarkably.

Inventors

• 👤 Akira Fujishima
• 👤 Isao Ariyoshi

Bibliographic Details