Demodulation circuit having triangular wave for blocking harmonics

摘要

A demodulator circuit for demodulating a signal which varies substantially sinusoidally with time, such as a stereo signal having a carrier frequency, comprises a mixer circuit having a first input with a linear transfer characteristic which receives the stereo multiplex signal um to be demodulated and having a second input with a substantially hyperbolic tangent transfer characteristic, the second input receiving a signal ud. The signal ud is a voltage having a triangular wave shape superimposed with the triangular wave shape having the carrier frequency. A stereo output signal L and R is produced having minimal third and fifth harmonics of the carrier frequency is produced from a matrix circuit as a result of the triangular shape and amplitude of the signal ud.