Low power radio telephone image reject mixer

摘要

An image reject mixer for a low power battery operated radio telephone application. First and second doubly balance mixer circuits are connected to receive a differential radio frequency signal. Each of the doubly balance mixer circuits receives a local oscillator signal and a complimentary quadrature local oscillator signal. A first and second differential current produced by the first and second doubly balance mixture are combined in a quadrature combining circuit. The quadrature combining circuit adds an additional 90° of phase shift between the pairs of signals produced by each doubly balance mixture, so that the mixture output signals are added in a phase quadrature relationship thereby canceling unwanted spur and image components contained in the respective mixer output circuits.