Adaptable digital delta-sigma modulator for multiband frequency synthesizer

In this paper, we propose an adaptable-order single-loop digital DeltaSigma modulator which offers flexible noise shaping performance to maximize hardware sharing and power efficiency in multi-band frequency synthesizer applications. The proposed architecture utilizes feedback coefficients that allow computationally efficient digital implementation and also yield good noise shaping. Fixed-magnitude quantizer dithering is employed to eliminate idle channel tones and also to suppress in-band noise more efficiently than input dithering structures. MATLAB simulation was carried out. Finally, the proposed architecture was implemented and verified in an FPGA device.