In one embodiment, RF front-end circuit includes a tunable matching network having an input coupled to an RF interface port, a directional coupler with a first connection coupled to an RF input of a mixer, a second connection coupled to an RF signal generation port, and a third connection coupled to an output of the tunable matching network. The directional coupler is configured to direct a signal from the RF signal generation port to the tunable matching network and to direct a signal from the tunable matching network port to the RF port of the mixer. The RF front-end circuit also has a tunable matching network control unit coupled to the tunable matching network. The control unit is configured to optimize an impedance match between the RF interface port and the output of the tunable matching network.