A Novel Analog VLSI Implementation of Wavelet Transform Based on SI Circuits

A general scheme for the VLSI implementation of wavelet transform using switched-current (SI) circuits is firstly presented in this paper. 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 (W/L) ratios and the clock frequency. The circuits are composed of analog filter bank whose impulse responses are the first derivative of Gaussian and its dilations. The transfer functions of the basic wavelet filter can be given by Pade approximation, which is able to 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 at different scales with a prescribed impulse response. Simulated results indicated a good performance of wavelet transform.