Amplitude Stabilization In Quadrature Oscilator For Low Harmonic Distortion

A simple non-linear network for amplitude stabilization in harmonic quadrature oscillator (QO) is analyzed. The oscillation startup conditions for QO topology with two operational amplifiers are used for amplitude adjustment by element values. A closed form expression for the amplitude setting resistance is derived. Total harmonic distortion (THD) is expressed as closed form function of the established amplitude. The derived expressions as well as the oscillator performance are verified by computer simulations and measurements.