Effect of non-linear settling error on the harmonic distortion of fully-differential switched-current bandpass /spl Sigma//spl Delta/ modulators

摘要

This paper presents a detailed study of the effect of the non-linear settling on the harmonic distortion of Bandpass /spl Sigma//spl Delta/ Modulators (BP-/spl Sigma//spl Delta/Ms) realized using Fully Differential (FD) Switched-current (SI) circuits. Based on the analysis of building blocks, closed-form expressions are derived for the third-order intermodulation distortion of BP-/spl Sigma//spl Delta/Ms due to defective settling, on the one hand, and to the non-linearities of the sampling process, on the other. Time-domain simulations and measurements taken from a 0.8 /spl mu/m CMOS 4th-order BP-/spl Sigma//spl Delta/M silicon prototype validate our approach.