A low distortion tri-wave to sine converter

A new triangle-to-sine shaper circuit is described based upon the modified transfer function of a differential pair of transistors. Computer-aided design techniques have been used to establish an optimized set of design criteria. Theoretical figures as low as six parts per million total harmonic distortion (t.h.d.) are possible with the circuit. Measurements taken on a prototype have fulfilled the promise of the circuit with t.h.d. figures of better than 0.05% with operation to 106 hertz.