A 83-dB SFDR 10-MHz Bandwidth Continuous-Time Delta-Sigma Modulator Employing a One-Element-Shifting Dynamic Element Matching

Abstract

This paper proposes a new dynamic element matching (DEM) method referred to as one-element-shifting (OES) for the implementation of high spurious-free dynamic range (SFDR) multi-bit Delta-Sigma modulators (DSMs). Generic DEM techniques are successful at suppressing the mismatch error and increasing the SFDR of data converters. However, they will induce additional glitch energy in most cases. Some recent DEM methods achieve improvements in minimizing glitch energy but sacrificing their effects in harmonic suppression due to mismatches. OES technique proposed in this paper can suppress the effect of glitch while preserving the reduction of element mismatch effects. Hence, this approach achieves better SFDR performance over the published DEM methods. With the proposed OES, a 3rd order, 10 MHz bandwidth continuous-time DSM is implemented in 90 nm CMOS process. The measured SFDR attains 83 dB for a 10 MHz bandwidth. The measurement result also shows that OES improves the SFDR by higher than 10 dB.