Point feedback

Point feedback is a system which measures the output distortion of a waveform and uses this measurement to provide a correcting input. Another way of looking at its operation is to regard it as being a circuit which provides a negative resistance. The precise circuit is described but two circuits are at the root of point feedback. The first is the authors 'error addon' of 1973 (later called 'error takeoff') the second a circuit due to Gomez and Jardonz (1996).