LOW NOISE OSCILLATORS AND TRACKING FILTERS

摘要

A gyrator based resonator comprises first and second differential amplifiers cross coupled to form a quadrature phase voltage controlled oscillator. The differential amplifier circuits include matched transistor pairs and associated transconductance adjusting components to control the resonant frequency of the resonator. Transconductance delay and admittance loss elements are also provided and these elements serve to control the loop gain of the resonator. A loop gain greater than unity results in the resonator oscillating while a loop gain less than unity produces a bandpass filter. A resonator having gain less than unity may be slaved to a similar resonator having gain adjusted to be greater than unity thus creating a low noise oscillator and tracking filter.