Two interconnected oscillators having adjustable coupling for controlling frequency

摘要

A first and a second fixed-frequency oscillator coupled in a ring topology to generate a variable frequency output is provided. Frequency variation is achieved by varying the coupling between the two oscillators. The coupling may be varied by using a variable current or voltage source. The first fixed frequency oscillator may generate a first signal which is ninety degrees out of phase with a second signal generated by the second fixed frequency oscillator. An apparatus is provided comprising a first oscillator which produces a first signal, a second oscillator which produces a second signal which is about ninety degrees out of phase with the first signal, and first and second coupling modules, coupling the first and second oscillators. A frequency control circuit is provided which varies the coupling of the first and second coupling modules and thereby varies the frequency of the first signal and the second signal.