Low Distortion Oscillators
To measure harmonic distortion, and other related measures such as THD+N, a sinusoidal oscillator is required. It should have very low distortion and noise, such that it does not limit the measurement resolution. Achieving this is a very demanding task, particularly if fast settling after a frequency change is also required. Below some findings from my studies of this topic.
Low Distortion Oscillator Design Master Thesis
This thesis is available for download: low_distortion_oscillator_design.pdf and low_distortion_oscillator_design_schematics.pdf.