Patent ID: 6871058

Claim:
A frequency conversion circuit comprising: a first amplifier formed of a first field effect transistor for amplifying a local oscillator signal input to a gate and outputting it from a drain; a mixer for converting a radio frequency signal into an intermediate frequency signal on the basis of a local oscillator signal output from the first amplifier; a second amplifier formed of a second field effect transistor for amplifying an intermediate frequency signal that is output from the mixer and is input to a gate and outputting it from a drain; a first resistor one end of which is grounded, the other end of which connected to the gate of the first field effect transistor; a second resistor connected between an external power source and the gate of the first field effect transistor; a first capacitor one end of which is grounded, the other end of which connected to the source of the first field effect transistor; a third resistor one end of which is grounded, the other end of which connected to the gate of the second field effect transistor; a second capacitor and a fourth resistor which are connected in parallel with each other, and one end of each of which is grounded, the other end of each of which connected to the source of the second field effect transistor; and an AC blocking circuit for passing direct current and blocking alternating current, the AC blocking circuit connected between the source of the first field effect transistor and the drain of the second field effect transistor.