VFO having plural feedback loops

摘要

An oscillator including a resonator having a primary feedback loop for causing oscillations to occur at a desired frequency and a secondary feedback loop including a multiplier for causing variations of said frequency in response to an input signal manifestation. Spectral purity is enhanced and potential overtone oscillations are suppressed by a cascade connection of lag networks in the primary loop which exhibit a low-pass transfer characteristic and provide at least pi radians of phase shift, one of the networks being shared in common with the secondary loop for supplying a quadrature signal to the multiplier.