An amplification unit is provided. The amplification unit, comprises a first amplifier, a second amplifier, a first sensor, a first predistortion component, and a signal combiner. The first amplifier amplifies a first signal to produce a second signal. The first sensor produces a third signal based on the second signal. The second amplifier turns on and to amplifies a fourth signal to produce a fifth signal when the amplitude of the fourth signal exceeds a threshold amplitude and turns off when the amplitude of the fourth signal is less than the threshold amplitude. The first predistortion component produces the first signal based on a first input signal, based on the third signal, and based on an on-off state of the second amplifier. The signal combiner produces an output of the amplification unit based on the second signal and the fifth signal.