ANALOG VLSI SIGNAL-PROCESSING - WHY, WHERE, AND HOW

Analog VLSI signal processing is most effective when precision is not required, and is therefore an ideal solution for the implementation of perception systems. The possibility to choose the physical variable t hat represents each signal allows all the features of the transistor t o be exploited opportunistically to implement very dense time- and amp litude-continuous processing cells. This paper describes a simple mode l that captures all the essential features of the transistor. This sym metrical model also supports the concept of pseudoconductance which fa cilitates the implementation of linear networks of transistors. Basic combinations of transistors in the current mirror, the differential pa ir, and the translinear loop are revisited as support material for the description of a variety of building blocks. These examples illustrat e the rich catalogue of linear and nonlinear operators that are availa ble for local and collective analog processing. The difficult problem of analog storage is addressed briefly, as well as various means for i mplementing the necessary intrachip and interchip communication.