On the Implicit Anti-Aliasing Feature of Continuous-Time Cascaded Sigma-Delta Modulators

• Published in: IEEE transactions on circuits and systems. I, Regular papers Vol. 54; no. 12; pp. 2639 - 2645
• Main Authors: Keller, M., Buhmann, A., Gerfers, F., Ortmanns, M., Manoli, Y.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2007; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analog-digital (A/D) conversion; Analog-digital conversion; anti-aliasing; Architecture; Bandwidth; Baseband; Capacitors; cascaded; Circuits; Computer simulation; continuous time; Covering; Digital modulation; Frequency; Jitter; MASH; Mathematical models; Modulators; Multi-stage noise shaping; Multistage; Noise shaping; sigma-delta (\Sigma\Delta); Signal sampling; Cascaded; Sigma-Delta; MASH; Continuous-Time; Anti-Aliasing; A/D Conversion
• ISSN: 1549-8328; 1558-0806
• DOI: 10.1109/TCSI.2007.906070

This paper deals with one of the most outstanding advantages of continuous-time (CT) sigma-delta modulators compared to their discrete-time counterparts: the implicit anti-aliasing feature (AAF). Although inherent in any CT architecture, analysis of anti-aliasing properties has mostly been restricted to single-stage modulators in the past. In this contribution, extensions on analysis methods for the study of the AAF of CT multistage noise-shaping architectures are covered. A theoretical model is introduced and confirmed through simulation results. Contrary to previous belief, the results indicate that usually all stages of a cascaded architecture are involved in the anti-aliasing behaviour and hence that it is not solely determined by the first stage.