Reduced Complexity MASH Delta–Sigma Modulator

A reduced complexity digital multi-stage noise shaping (MASH) delta-sigma modulator for fractional-N frequency synthesizer applications is proposed. A long word is used for the first modulator in a MASH structure; the sequence length is maximized by setting the least significant bit of the input to ldquo1;rdquo shorter words are used in subsequent stages. Experimental results confirm simulations.