Singly-balanced active mixer circuit

A singly-balanced active mixer circuit is disclosed for developing an IF signal by combining a RF signal and a local oscillator (LO) signal. The RF and LO signals are applied to a strip transmission line ring (100) which provides balanced components of the LO signal to a pair of active devices (120, 121) arranged in a singly-balanced active mixer. The active devices (120, 121) are coupled directly, or via a balanced Pi-network (129-131) to the primary winding of an output transformer (132) for application to the following IF stage of the radio receiver. The singly balanced active mixer circuit may be advantageously utilized in a radio having a receiver with broadband front-end RF selectivity.