Patent ID: 7620382
Filing Date: 2009-11-17
Classification: H03D

Abstract:
1. A frequency converter comprising: a mixer that frequency-converts a received signal to an intermediate frequency signal and has a mixer transistor; an oscillation circuit that supplies an local oscillation signal to the mixer and has an oscillation transistor; a resonating circuit coupled to the oscillation transistor and having a varactor diode, a control voltage for controlling an oscillation frequency being applied to a cathode of the varactor diode; and a bias power supply for setting a collector bias current of the mixer transistor and a collector bias current of the oscillation transistor, wherein the received signal and the local oscillation signal are input to the mixer transistor, and when the control voltage is equal to or smaller than a first predetermined value, an output voltage of the bias power supply is set to be increased so that at least one of the collector bias current of the mixer transistor and the collector bias current of the oscillation transistor can be increased.