Title :
Static feedback circuit methodology for solving fixed-point equations
Author :
Taylor, Robert M., Jr. ; Das, Shamik ; Greenwald, Hal S.
Author_Institution :
MITRE Corp., McLean, VA, USA
Abstract :
In this paper we consider the use of static analog VLSI circuits for iteratively maximizing cost functions that admit a fixed point recursion. We show through circuit simulation that certain classes of fixed point equations can be solved iteratively via the settling to steady state equilibrium of properly designed static-feedback CMOS circuits biased in the subthreshold region of operation. To demonstrate the power of this approach, we design a family of circuits to compute the right principal singular vector of arbitrarily sized positive real matrices by casting the singular vector extraction problem into a fixed point iterative map. We also illustrate the methodology more simply with a square root solver that uses the Babylonian fixed point equation. All circuits are current-mode translinear circuits with no extrinsic capacitors. This permits fast, low-power computation since the principal delay component is the settling time of the static circuits, and the few transistors required are biased in weak inversion.
Keywords :
CMOS analogue integrated circuits; circuit feedback; circuit simulation; current-mode circuits; iterative methods; Babylonian fixed point equation; circuit simulation; current-mode translinear circuits; fixed point recursion; iteratively maximizing cost functions; principal delay component; settling time; singular vector extraction problem; square root solver; static analog VLSI circuits; static circuits; static feedback circuit methodology; static-feedback CMOS circuits; steady state equilibrium; Equations; Mathematical model; Matrix decomposition; Optimization; Signal processing; Transistors; Very large scale integration;
Conference_Titel :
New Circuits and Systems Conference (NEWCAS), 2011 IEEE 9th International
Conference_Location :
Bordeaux
Print_ISBN :
978-1-61284-135-9
DOI :
10.1109/NEWCAS.2011.5981234