Title :
Design of continuous-time sigma-delta modulators with arbitrary feedback waveform
Author_Institution :
Labs., Motorola Inc., Schaumburg, IL, USA
Abstract :
This paper considers the discretization of continuous-time sigma-delta modulators without any constraint on the shape or duration of the feedback signal. A motivation for taking the shape of the feedback signal into account is the system-level compensation of nonidealities encountered in a practical design. Two different discretization approaches based on state-variables and the modified z transform are presented. Explicit formulas for an exact mapping between continuous-time and discrete-time modulators are derived. Subsequently, design of multistage continuous-time modulators using arbitrary feedback waveforms is discussed.
Keywords :
Z transforms; cascade networks; circuit feedback; continuous time systems; modulators; network synthesis; sigma-delta modulation; arbitrary feedback waveform; continuous-time modulators; discretization approaches; feedback signal; modified z transform; multistage modulators; nonidealities; oversampling data converter; sigma-delta modulators; state-variables; system-level compensation; Delta-sigma modulation; Digital modulation; Feedback; Linear systems; Modulation coding; Nonlinear filters; Prototypes; Sampling methods; Shape; Signal generators;
Journal_Title :
Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on
DOI :
10.1109/TCSII.2003.814806
