The Analog Wavelet Chip for Speech Compression - Chip Specifications

This paper describes the implementation in CMOS technology of a circuit which performs analog wavelet decompositions of a one-dimensional (e.g., sound) input. The circuit is based on the Analog VLSI techniques described by Carver Mead in Analog VLSI and Neural Systems [1]. The analog wavelet outputs are the output of a logarithmically scaled set of bandpass filters; each band is to be sampled (externally) at a rate proportional to the Nyquist rate of the highest frequency content of that band. The result is a matrix of discrete points describing the input signal as a function of both frequency and time. The filter function of each band is gaussian shaped in order to best resolve the uncertainty relation between time and frequency at each sampled point. This chip has been designed by Tim Edwards under the direction of Michael Godfrey, and fabricated by MOSIS. Zilog Corporation of Campbell, California, provided the funding for this project. 1 Overview This paper describes the Analog Wav..