A mixer includes a trans conductance unit, a gain boost unit, a mixing module and a buffer. The trans conductance unit, the gain boost unit and the mixing module cooperatively mix a differential input voltage signal pair with a differential oscillatory voltage signal pair to generate a differential mixed voltage signal pair. The buffer performs buffering on the differential mixed voltage signal pair, and has inductance that cooperates with parasitic capacitance at output terminals thereof to form an LC tank circuit that reaches resonance at a frequency of the differential mixed voltage signal pair to behave as an open circuit.

Mixer circuitry can include a first mixer transistor configured to receive a first oscillating signal, a second mixer transistor configured to receive a second oscillating signal, and a harmonic conversion gain rejection filter coupled between a source terminal of the first mixer transistor and a source terminal of the second mixer transistor. The harmonic conversion gain rejection filter can be configured to reject a harmonic conversion gain of the mixer circuitry. The mixer circuitry can further include a third mixer transistor configured to receive the first oscillating signal, a fourth mixer transistor configured to receive the second oscillating signal, and another harmonic conversion gain rejection filter coupled between a source terminal of the third mixer transistor and a source terminal of the fourth mixer transistor. The mixer circuitry can further include an output transformer and a notch filter interposed between coils of the output transformer.