Analogue wavelet transform with single biquad stage per scale

A new approach to obtain the wavelet transform with easily constructed analogue circuits is presented. It is shown that the impulse response of a bandpass biquad filter satisfies the conditions to be considered a mother wavelet. Using this, an integrated circuit performing the wavelet transform at 16 scales along eight octaves has been designed. The design has CMOS transistors working in the subthreshold region with a total power consumption of 650 nW. On-chip measurements are reported.