A computational approach to VLSI analog design

A new technique for the design of analog VLSI is described. Borrowing from digital design technology concepts, an analog processor is described which can be digitally programmed to execute a small but powerful set of analog operations. At a very high level of abstraction these instructions can be used to perform mathematical processing on analog signals directly rather than through the traditional processing chain of sampling, A/D conversion, digital processing, and D/A conversion. A key feature of the technique is the conversion of signals into logarithmic form, and the practical problems associated with this are discussed and their solutions outlined. Finally implementation of these techniques in BiCMOS, CMOS, and bipolar technologies is discussed with conclusions.