Patent ID: 6859085
Filing Date: 2005-02-22
Classification: H03D,H03F

Abstract:
1. A mixer circuit comprising: a differential amplifier circuit having an RF signal input port for receiving an RF signal; and a double-balanced mixer circuit having a first LO signal input port for receiving an LO signal, a second LO signal input port for receiving an inverted LO signal equal in frequency and amplitude to the LO signal and opposite in phase to the LO signal, a first IF signal output port for outputting an IF signal obtained by mixing the RF signal with the LO signal, and a second IF signal output port for outputting an inverted IF signal equal in frequency and amplitude to the IF signal and opposite in phase to the IF signal, the double-balanced mixer circuit receiving an output signal from the differential amplifier circuit, the differential amplifier circuit having: a first transistor having a control portion for receiving the RF signal inputted to the RF signal input port to output an amplified RF signal in response to the RF signal; a second transistor having a control portion for receiving a virtual inverted RF signal to output an amplified inverted RF signal in response to the virtual inverted RF signal; a capacitor provided between the control portion of the second transistor and a ground; and a resonating means connected to the RF signal input port, the control portion of the first transistor, and the control portion of the second transistor, the resonating means including the capacitor, the resonating means being provided to reduce a harmonic of the RF signal.