We analyze in-band thermal noise in continuous-time delta sigma modulators (CTDSMs) with Switched-Capacitor feedback DACs. We show that in such modulators, noise from around multiples of the sampling frequency aliases to in-band frequencies. We give an intuitive understanding of this phenomenon and describe a model that can be used to analyze noise in such modulators. We present the results obtained using state space analysis. Our results compare well with those obtained from a circuit simulator. © 2012 IEEE.

Shanthi Pavan Y

Department of Electrical Engineering

Radha S. Rajan

Circuit simulators

Continuous time

DELTA SIGMA MODULATOR

DEVICE NOISE

In-band

Intuitive understanding

Sampling frequencies

STATE-SPACE ANALYSIS

Switched Capacitor

Circuit simulation

Continuous time systems

MODULATORS

Capacitors

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IIT Madras

Device noise in continuous-time ΔΣ modulators with Switched-Capacitor feedback DACs

ISCAS 2012 - 2012 IEEE International Symposium on Circuits and Systems

We analyze the in-band thermal noise of continuous-time delta sigma modulators. The manifestation of noise in converters with time-invariant loop filters is straight forward and well known. However, several practically useful modulators, like those with switched-capacitor-resistor (SCR) and return-to-open (RTO) feedback DACs, have a time-varying loopfilter. We give a framework for analyzing the noise performance of such designs, and show that it is important to consider the aliasing of noise from around multiples of the sampling frequency. Our results compare well with those obtained from a circuit simulator. © 2012 IEEE.

IEEE Transactions on Circuits and Systems I: Regular Papers

Device noise in continuous-time oversampling converters

Continuous-time ΔΣ modulators (CTDSMs) with switched-capacitor (SC) feedback digital-to-analog converters (DACs) are relatively less sensitive to clock jitter when compared to converters that use non-return-to-zero feedback DACs. However, as we show in this paper, using an SC DAC can seriously compromise the alias rejection of the modulator, thereby nullifying one of the principal advantages of continuous-time operation. We give an intuitive understanding, as well as an analytical basis, for computing the signal transfer function of CTDSMs with SC DACs. We propose power-efficient circuit techniques to improve alias rejection in such modulators and give experimental results that illustrate some of our ideas. © 2011 IEEE.

Alias rejection of continuous-time ΔΣ modulators with switched-capacitor feedback DACs

IEEE Journal of Solid-State Circuits

A 2.7-mW 2-MHz Continuous-Time $Sigma Delta$ Modulator With a Hybrid Active–Passive Loop Filter

A continuous-time /spl Sigma//spl Delta/ Modulator with reduced sensitivity to clock jitter through SCR feedback

IEEE Transactions on Circuit Theory

Exact Analysis of Linear Circuits Containing Periodically Operated Switches with Applications

Journal	Data powered by TypesetISCAS 2012 - 2012 IEEE International Symposium on Circuits and Systems
Publisher	Data powered by TypesetInstitute of Electrical and Electronics Engineers Inc.
Open Access	No