Hybrid loopfilter sigma-delta modulator with NTF zero compensation

Author

Hussain, Arshad ; Sin, Sai-Weng ; Seng-Pan U ; Martins, Rui P.

Author_Institution

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

fYear

2011

fDate

17-18 Nov. 2011

Firstpage

76

Lastpage

79

Abstract

A low power second order hybrid loopfilter Sigma-Delta modulator with high resolution is presented. The structure is composed by a first active integrator followed by a switched-capacitor (SC) integrator. This modulator architecture exploits the coefficient scaling property of the active integrator, while the SC integrator is modified to shift its pole from inside the unit circle to z=1 at DC in the z-domain. Poles of the loopfilter are zeroes of the noise transfer function (NTF). As a result the NTF zero is also shifted to z=1. This NTF zero compensation for the SC integrator will result in better in-band noise suppression & improved noise shaping. The second order hybrid sigma-delta modulator with a 4-bit quantizer and an oversampling ratio (OSR) of 32 is simulated in simulink. The modulator can achieve 89dB SNDR with a dynamic range of 91dB.

Keywords

sigma-delta modulation; switched capacitor filters; NTF zero compensation; SC integrator; SNDR; active integrator; improved noise shaping; in-band noise suppression; low power second order hybrid loopfllter sigma- delta modulator; noise transfer function; switched-capacitor integrator; word length 4 bit; Sigma-Delta; Switched Capacitor;

fLanguage

English

Publisher

ieee

Conference_Titel

SoC Design Conference (ISOCC), 2011 International

Conference_Location

Jeju

Print_ISBN

978-1-4577-0709-4

Electronic_ISBN

978-1-4577-0710-0

Type

conf

DOI

10.1109/ISOCC.2011.6138650

Filename

6138650