Dual band phase locked loop frequency synthesizer for wireless communication, has divide by three circuit allowing use of same oscillator circuit to get center and offset frequencies in phases added and subtracted by mixer

摘要

The synthesizer has an oscillator circuit (VCO) (10) generating a frequency at an output of the circuit. A quadrature divide by three circuit (20) is coupled to the output of the oscillator circuit to generate an offset frequency at the output of the oscillator circuit. A double quadrature mixer is coupled to the output of the oscillator and the divide by three circuits to generate either of the output frequencies. The divide by three circuit allows utilization of the same VCO to get the center and the offset frequencies in quadrature phases that are added and subtracted by the mixer.