Quadrature switching mixer with reduced leakage

A quadrature switching mixer is provided for mixing a received RF signal and a local oscillator signal, while rejecting an image signal associated with the RF signal. Input signal components in quadrature, that is, I and Q input components derived from the received RF signal, are respectively coupled through first and second input paths to corresponding commuting switches in a configuration of switches. Each of the switches operates to multiply respective quadrature components of RF and local oscillator signals to provide quadrature output signal components. A unidirectional device, such as a buffer amplifier included in a signal splitter, is placed in each input path to prevent any portion of an output signal component from leaking backward through one of the input paths to the other input path, and thus to the other output signal component.