N-path baseband down-conversion with bias current steering and sinusoidal voltage drivers for transistor commutation

Abstract

A receiver circuit comprises a radio frequency (RF) input terminal, a shared current source that draws a shared bias current from a DC voltage supply, a local oscillator (LO) that provides sinusoidal voltage signals, and baseband down-conversion paths that provide baseband down-conversion signals. Each baseband down-conversion path comprises a transistor, a load impedance, and a filter capacitor. The transistor has a drain coupled to the impendence load and the filter capacitor. The drain is configured to provide a mixed signal in response to one of the sinusoidal voltage signals, the shared bias current, and the RF input signal. The filter capacitor provides the baseband down-conversion signal in response to the mixed signal. A method of baseband down-conversion comprises steering the shared bias current to configure the transistor to operate in a saturation mode in response to a time-varying amplitude of the sinusoidal voltage signal at a gate of the transistor.