Study of non-ideal effects in a CT [...][Delta]modulator with decaying exponential feedback waveforms

In this article, a detailed theoretical analysis of the impact of finite gain-bandwidth product (GBW) in amplifiers, excess loop delay, and a hysteretic quantiser on a second order, 3-bit, continuous-time sigma-delta (CT ...) modulator with decaying exponential feedback pulses has been accomplished....

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Bibliographic Details
Published in:International journal of electronics 2014-02, Vol.101 (2), p.143
Main Authors: Quintanilla, L, Arias, J, Enriquez, L, Hernandez-Mangas, J M, Vicente, J
Format: Article
Language:English
Subjects:
Bandwidths
Feedback control systems
Simulation
Waveform analysis
Online Access:Get full text
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Summary:In this article, a detailed theoretical analysis of the impact of finite gain-bandwidth product (GBW) in amplifiers, excess loop delay, and a hysteretic quantiser on a second order, 3-bit, continuous-time sigma-delta (CT ...) modulator with decaying exponential feedback pulses has been accomplished. A "short" exponential pulse -- namely, an exponential pulse whose time constant is lower than the pulse width -- was used in order to improve jitter rejection. An overall noise transfer function (NTF) that includes the effect of the three non-ideal effects was analytically calculated using the modified Z-transform method. The evolution of the NTF poles and zeroes locus in the z-plane is obtained when these effects are taken into account separately or combined. System-level simulations have been also carried out in order to validate the proposed theoretical study. The stability of a modulator with "short" exponential feedback pulses is higher than that of a modulator with rectangular ones when finite GBW or excess loop delay are included. Finally "short" exponential pulses and "narrow" rectangular ones are proved to be equivalent from the stability viewpoint. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:0020-7217
1362-3060