What circuit is required at the output of an RF switching amplifier?
A filter to remove harmonic content✓Bonne réponse
A high-pass filter to compensate for low gain at low frequencies
A matched load resistor to prevent damage by switching transients
A temperature compensating load resistor to improve linearity
Explication
A switching amplifier's output is a square-wave-like waveform, which is rich in harmonics of the operating frequency. A filter at the output is therefore mandatory to attenuate those harmonics before the signal reaches the antenna.