CURRENT MODE BLIXER WITH NOISE CANCELLATION

摘要

A blixer is provided that improves linearity and reduces noise over other conventional blixer designs. To accomplish this, the blixer provided here uses a differential amplifier and/or a dummy path within its mixing circuit to perform noise reduction (and improve linearity). In a described example, an apparatus includes a transconductance circuit (202) generates amplified signals from an input signal (VIN). A mixing circuit (204-1) mixes the amplified signals with a mixing signal (LOF1) having a duty cycle that is a fraction (generally 50% or 25%) of a local oscillator signal so that a differential amplifier (214) and impedance networks (e.g., resistors R7, R8 and switch S2, or resistors R9, RIO and switch SI) can perform noise reduction. The mixing is performed by mixers (210, 212) which are typically passive mixers (e.g., Gilbert cell passive mixers).