Frequency Synthesis for Integrated Transceivers

Abstract

With the recent increase in radio transceiver integration levels it has become feasible to use more complex frequency synthesizer structures. The use of a fractional-N synthesizer decouples the channel spacing from the choice of synthesizer reference frequency which enables much faster frequency hopping. Static moduli synthesizers have required complex spurious compensation methods, but recently, ΔΣ-dithered moduli fractional-N synthesizers have attracted a lot of attention as no analog spurious-compensation circuits are needed. Design equations for the analog parts of a ΔΣ-based synthesizer are presented together with a discussion on practical implementation aspects.