| 摘要 |
An oscillator is provided with an oscillation circuit including two oscillation transistors (Q2,Q1), comprising a differential pair, and a resonance circuit (RSNa) connected in common to the bases of the oscillation transistors (Q2,Q1). The bases of the oscillation transistors (Q2,Q1) are short-circuited by a coil (L2), a center tap coil (L3) is connected in parallel to the resonance circuit (RSNa), and variable capacitance diodes (VC1,VC2) in the resonance circuit (RSNa) are driven by a coil (L4) connected to a mixing circuit (MIX). Due to this, it is possible to prevent the occurrence of low frequency noise, possible to realise a completely balanced operation, possible to avoid the oscillation carrier flowing into the power source and ground, and, when the oscillation circuit is used in a television tuner, possible to reduce the noise in a television picture. <IMAGE> |
