DocumentCode :
1225188
Title :
A Polyphase Filter Design for Continuous-Time Quadrature Bandpass Sigma–Delta Modulators
Author :
Kim, Song-Bok ; Robens, Markus ; Joeres, Stefan ; Wunderlich, Ralf ; Heinen, Stefan
Author_Institution :
RWTH Aachen Univ., Aachen
Volume :
55
Issue :
11
fYear :
2008
Firstpage :
3457
Lastpage :
3468
Abstract :
This paper presents a strategy for successful polyphase-filter design for continuous-time quadrature bandpass sigma-delta (SigmaDelta) modulators. Based on a low-pass filter with a chain of integrators with weighted capacitive feedforward summation (CICFF) topology - which is suited for implementation in low-power applications - analytical equations are derived. A new compensation scheme is proposed and implemented by cross-coupling additional resistors, without the necessity of extra-active components. Translation to intermediate frequency in second- and fourth-order polyphase filters with the proposed compensation scheme are compared to analytical considerations and simulation. Nonlinearities introduced by mismatch of feedforward coefficients and finite gain-bandwidth of amplifiers are considered.
Keywords :
continuous time filters; low-pass filters; sigma-delta modulation; amplifiers; analytical equations; compensation scheme; continuous time quadrature bandpass sigma-delta modulators; feedforward coefficients; finite gain bandwidth; intermediate frequency; low pass filter; nonlinearities; polyphase filter design; weighted capacitive feedforward summation topology; Analog–digital conversion; CICFF; CIFF; analog-digital conversion; chain of integrators with weighted capacitive feedforward summation (CICFF); chain of integrators with weighted feedforward summation (CIFF); complex filter; continuous-time (CT) circuit; continuous-time circuit; polyphase filter; quadrature bandpass sigma–delta modulator; quadrature bandpass sigma-delta modulator;
fLanguage :
English
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
Publisher :
ieee
ISSN :
1549-8328
Type :
jour
DOI :
10.1109/TCSI.2008.925352
Filename :
4526190
Link To Document :
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