Abstract: The invention relates to a dual band frequency synthesizer for generating either a first output frequency fhigh or a second output frequency flow, where fhigh=2 flow, comprising an oscillator circuit for generating at its output a frequency fVCO=(fhigh+flow)/2, a divide by three (3) circuit, coupled to the output of the oscillator circuit, for generating at its output an offset frequency fDB3=fVCO/3, and a double quadrature mixer circuit, coupled to the output of the oscillator circuit and to the output of the divide by three circuit, for generating either the first output frequency fhigh=fVCO+fDB3 or the second output the frequency flow=fVCO?fDB3.