An analog wavelet transform chip
R. Timothy Edwards, Michael D. Godfrey · 2002
The theory and implementation in subthreshold analog CMOS technology of a circuit which performs continuous wavelet decompositions of a one-dimensional (e.g., audio) input are described. The analog wavelet outputs are the output of a logarithmically scaled bank of bandpass filters; each band is sampled 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.>