Because of its dilation property, the wavelet transform is the preferred approach for processing broadband signals in both civil and military environments. Unfortunately, its computation requires a large number of numerical operations. In many situations, this may be prohibitively expensive is not unrealistic. Analog parallel processing techniques including optical methods are either unsuitable or not accurate enough for practical applications, and hence, for possible commercialization. Switched-capacitor techniques, which substitute appropriate combinations of high- speed switches and capacitors for resistors, are not used in VLSI implementations of active filter designs. The most important property of a switched-capacitor circuit is that its clock frequency controls the filter parameters. The purpose of this proposal is to implement the wavelet transform using switched-capacitor circuits. What makes this possibility is the observation that the dilation effect in a wavelet filter can be realized by the adjusting of the clock frequency. By using current VLSI techniques based on the proposed scheme, large numbers of wavelet filter channels can be fabricated on a single chip. These IC chips can be used as standard components in a signal processing unit having increased resolution. They will also offer reliable real-time processing and full compatibility with other state-of-the-art electronic equipment. Near future commercialization of these devices is anticipated.
