A robust NTF zero optimization technique for both low and high OSRs sigma-delta modulators

Author

Yun Du ; Tao He ; Yang Jiang ; Sai-Weng Sin ; Seng-Pan U ; Martins, Rui P.

Author_Institution

State-Key Lab. of Analog & Mixed Signal VLSI, Univ. of Macau, Macao, China

fYear

2012

fDate

2-5 Dec. 2012

Firstpage

29

Lastpage

32

Abstract

This paper introduces a novel loop filter scheme with embedded noise transfer function (NTF) zero optimization in a feed-forward topology. This new structure allows the relaxation of the requirement of the local feedback coefficient. Moreover, the merit of zero optimization is compatible with high oversampling ratio (OSR) when compared with the traditional loop filter. Besides, the practical implementation exhibits less sensitivity to the capacitor ratio mismatches. A second order discrete-time (DT) sigma-delta (ΣΔ) modulator with the proposed loop filter is designed and simulated with Matlab and Cadence. The performance of the modulator can reach 70.1dB/99.3dB SNDR in a 10MHz bandwidth, with OSR 12/48 and the corresponding coefficients in the local feedback 0.4/0.34, respectively.

Keywords

optimisation; sigma-delta modulation; transfer functions; Cadence; Matlab; OSR; capacitor ratio mismatch; embedded noise transfer function zero optimization; feedforward topology; local feedback coefficient; loop filter; oversampling ratio; robust NTF zero optimization technique; second order discrete time sigma delta modulator; Bandwidth; Modulation; Noise; Noise shaping; Optimization; Sigma delta modulation; Transfer functions;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems (APCCAS), 2012 IEEE Asia Pacific Conference on

Conference_Location

Kaohsiung

Print_ISBN

978-1-4577-1728-4

Type

conf

DOI

10.1109/APCCAS.2012.6418963

Filename

6418963