Second order MASH /spl utri//spl Sigma/FDM-solution with adaptive improvements

Abstract

This paper presents a new, adaptive improvement to a novel second order frequency-to-digital cascaded delta sigma modulator. The adaptive corrections significantly reduce the sensitivity to analog imperfections in the MASH-like /spl utri//spl Sigma/ frequency-to-digital modulator (/spl utri//spl Sigma/FDM), and makes it possible to implement the circuit in standard digital CMOS without loosing performance. The result is a simple second order delta-sigma modulator with high precision. Simulations of the circuit with errors and corrections are included to confirm the theory.