Analog implementation of wavelet transform based on switched-current filter circuits

Abstract

A general scheme for the analog implementations of wavelet transform using switched_current (SI) filter circuits is presented. SI circuits are well suited for this application since the dilation constant across different scales of the transform can be precisely implemented and controlled by both the transconductance ratios (W/L) and the clock frequency. The circuits are composed of analog filter banks whose impulse responses are the first derivative of Gaussian and its dilations. The transfer functions of the basic wavelet filter can be given by Pad approximation, which can decompose the transfer function into rational form so as to be conveniently implemented by SI circuits. Therefore, it can easily be applied to other filters with a prescribed impulse response. Simulated results indicated a good performance of wavelet transform.