Patent ID: 7676212

Claim:
A mixer, comprising: a differential input circuit that is configured to receive an input signal and that comprises: a first transistor and a second transistor configured as a differential amplifier to convert the input signal from at least one voltage signal to first and second current signals; and a first cancellation circuit and a second cancellation circuit, wherein the first cancellation circuit comprises a third transistor including an emitter that communicates with a base of the third transistor, wherein the second cancellation circuit comprises a fourth transistor including an emitter that communicates with a base of the fourth transistor, wherein the first and second cancellation circuits are configured to receive the input signal, wherein collectors of the first and second cancellation circuits are in cross-communication with collectors of the differential amplifier of the differential input circuit, and wherein the first and second cancellation circuits cancel non-linear capacitance associated with the differential amplifier; a tank circuit that comprises a tuning capacitor arranged in parallel with an inductor, wherein a resonant frequency of the inductor and tuning capacitor is substantially centered around a predetermined frequency of the input signal, wherein the tank circuit is in communication between a ground and common emitters of the differential amplifier of the differential input circuit, and wherein the tank circuit is configured as a passive current source; and a mixer circuit that communicates with the differential input circuit and that is configured to receive the first and second current signals and a second input signal, and wherein the mixer circuit is configured as a Gilbert cell double-balanced switching mixer for generating a differential mixer output signal as a product of the first and second current signals and the second input signal.