A variable impedance circuit includes a matching network for coupling to a tunable device, where the matching network has a first port and a second port, where the tunable device is coupled to one of the first port or the second port, and where the matching network has one or more variable dielectric capacitors. The one or more variable dielectric capacitors can be operable to receive a first of one or more variable voltage signals to cause the one or more variable dielectric capacitors to change a first impedance of the matching network. The tunable device can be operable to receive a second of one or more variable voltage signals to cause a change in a second impedance of the tunable device.