embodiments of the present invention comprise methods and devices for amplifying a signal by amplifying a first signal and by then amplifying a second signal only if the first signal exceeds a predetermined threshold . the first and second amplified signals are then combined , and the combination is fed back to a signal source and used to control the values of the first and second signal . the combination is further transmitted to a load . in the preferred embodiment , the first amplified signal is transmitted through an impedance inverter before it is combined with the second amplified signal .