A radio frequency (RF) amplifier has a driver device, an output device, and first and second impedance transformation networks. In a first operating mode the output device is turned on and the first impedance transformation network presents a first load impedance to the output device. In a second operating mode, the output device is turned off and the second impedance transformation network connects an output of the driver device to the first impedance transformation network and presents a second load impedance to the driver device. The second load impedance is greater than the first load impedance.