Direct Digital Wavelet Synthesis for Embedded Biomedical Microsystems

Abstract

This paper presents a compact direct digital wavelet synthesizer for extracting phase and amplitude data from cortical recordings using a feed-forward recurrent digital oscillator. These measurements are essential for accurately decoding localfield-potentials in selected frequency bands. Current systems extensively to rely large digital cores to efficiently perform Fourier or wavelet transforms which is not viable for many implants. The proposed system dynamically controls oscillation to generate frequency selective quadrature wavelets instead of using memory intensive sinusoid/cordic look-up-tables while retaining robust digital operation. A MachXO3LF Lattice FPGA is used to present the results for a 16 bit implementation. This configuration requires 401 registers combined with 283 logic elements and also accommodates real-time reconfigurability to allow ultra-lowpower sensors to perform spectroscopy with high-fidelity.