Adaptive log domain filters for system identification using floating gate transistors

Authors:
Yiming Zhai;Pamela Ann Abshire
Affiliations:
Department of Electrical and Computer Engineering and the Institute for Systems Research, University of Maryland, College Park, USA 20742;Department of Electrical and Computer Engineering and the Institute for Systems Research, University of Maryland, College Park, USA 20742
Venue:
Analog Integrated Circuits and Signal Processing
Year:
2008

Citing 3
Cited 0

Stable adaptive systems

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Programmable and Adaptive Analog Filters using Arrays of Floating-Gate Circuits

ARVLSI '01 Proceedings of the 2001 Conference on Advanced Research in VLSI

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Abstract

We describe an adaptive log domain filter with integrated learning rules for model reference estimation. The system is a first-order low pass filter implemented using multiple input floating gate transistors operating in subthreshold to realize on-line learning of gain and cut-off frequency. We use adaptive dynamical system theory to derive robust control laws for gain and cut-off frequency adaptation in a system identification task. Simulation results show that convergence is slower using simplified control laws but still occurs within milliseconds. Experimental results confirm that the estimated gain and cut-off frequency track the parameters of the reference filter. The adaptive log domain filter has measured power consumption of 33 μW. During operation, deterministic errors are introduced by mismatch within the analog circuit implementation. An analysis is presented which attributes the errors to current mirror mismatch.