Analog VLSI Processor Implementing the Continuous Wavelet Transform

Abstract—We present an integrated analog processor for real-time wavelet decomposition and reconstruction of continuous temporal signals covering the audio frequency range. The processor performs complex harmonic modulation and Gaussian lowpass filtering in 16 parallel, identical channels, each channel clocked at a different rate, to produce a multiresolution mapping on a logarithmic frequency scale. Our implementation uses mixed-mode analog and digital circuits, oversampling techniques, and switched-capacitor filters to achieve a wide linear dynamic range while maintaining compact circuit size and low power consumption. We include experimental results on the 16-channel processor, and characterize its components separately from measurements on a reduced-scale (single-channel) test chip.