Analysis on in-band distortion caused by switching amplifiers

A hypothetical model is built to explain an in-band distortion mechanism of the class F amplifier. Using the model it is analytically proved that static non-linearities of switching amplifiers do not cause meaningful in-band distortion when the amplifiers are driven by ideal 1-bit digital RF signals. It is also found that short-term memory effects significantly contribute to in-band distortion. The analysis and the mechanism are tested and supported by MATLAB simulations. A system composed of a field-programmable gate array and a class F amplifier has been built and the in-band distortion mechanism is verified by measurement.