Frequency converter circuit

Claim 1

A frequency converter circuit for converting a high-frequency signal into an intermediate frequency signal, comprising: a local oscillation circuit including: a first transistor having first, second and third terminals, said first terminal of said first transistor being coupled to ground through a first inductance and a first capacitor, a second capacitor connected between said second and third terminals, and a resonance circuit having variable-capacity diodes and a second inductance, said resonance circuit being connected to said second terminal of said first transistor through a third capacitor; and a mixer circuit including: a second transistor having a base connected to said first terminal of said first transistor so that an oscillation frequency signal is supplied from said first terminal of said first transistor to a base of said second transistor, said second transistor further comprising an emitter connected to a high frequency signal inputting terminal for inputting a high frequency signal to said second transistor, wherein said collector of said second transistor outputs an intermediate frequency signal which intermediate frequency signal is the difference signal between said oscillation frequency signal applied to the base of said second transistor and said high frequency signal applied to said emitter of said second transistor, and further wherein the emitter of said second transistor is connected to ground through impedances which substantially become zero with respect to said intermediate frequency signal.