2020 E-Contest Question E-Amplifier Nonlinear Distortion Research Device (Dalian University of Technology)

This design is a simple amplifier nonlinear distortion research device that can output sine wave signals without obvious distortion and four different distortion waveforms according to requirements. In this design, the controlled transistor amplifier circuit is the core circuit. Five independent signal generation circuits are used in the circuit to generate the five waveforms required by the question, and the analog switch chip CD4066 is used to realize the switching of the final output waveform. In the sampling analysis part, an operational amplifier is used to build a signal processing circuit to convert the output waveform into two signals with completely opposite phases. The AD sampling port of the 32 microcontroller is used for acquisition, and ST's official FFT library is called to perform fast Fu on the collected signal. Liye transform is used to obtain the amplitude of each harmonic, and thereby obtain the frequency of the output signal, total harmonic distortion and other information.