Noise-Sensitive Feedback Loop Identification in Linear Time-Varying Analog Circuits

Ang Li1,a, Peng Li1,b, Tingwen Huang2 and Edgar Sánchez-Sinencio1,c
1Department of Electrical and Computer Engineering, Texas A&M University, College station, TX.
2Texas A&M University at Qatar, P.B.O.X. 23874, Doha, Qatar.


The continuing scaling of VLSI technology and design complexity has rendered robustness of analog circuits a significant concern. Parasitic effects may introduce unexpected marginal instability within multiple noise-sensitive loops and hence jeopardize circuit operation and processing precision. The Loop Finder algorithm has been recently proposed to allow detection of noise-sensitive return loops for circuits that are described using a linear time-invariant (LTI) system model. However, many practical circuits such as switched-capacitor filters and mixers present time-varying behaviors which are intrinsically coupled with noise propagation and introduce new noise generation mechanisms. For the first time, we take an in-depth look into the marginal instability of linear periodically time-varying (LPTV) analog circuits and further develop an algorithm for efficient identification of noise-sensitive loops, unifying the solution to noise sensitivity analysis for both LTI and LPTV circuits.

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