Nanopower sampled data wavelet filter design using Switched Gain Cell technique
Chutham Sawigun, Michiel Grashuis, Ralf Peeters, Wouter A. Serdijn · 2009
In order to realize a nano-power wavelet filter for biomedical applications, this paper applies the Singular Value Decomposition approximation to transform the time domain 1st-derivative of a Gaussian (gauss1) wavelet base into a 5th-order z-domain transfer function. Consequently, to realize the approximated transfer function in CMOS technology employing circuitry that operates from a low supply voltage, a sampled data circuit technique, coined ‘Switched Gain Cell, (SGC),’ is introduced. Using the SGC technique, standard MOS switches, simple subthreshold (nonlinear) transconductors and their associated parasitic capacitances suffice to constitute the filter, while the scale of the filter can be controlled by the clock frequency. This renders the filter architecture to be simple, modular, and area efficient. Simulation results, using 0.13µm CMOS model parameters, show that the wavelet filter implements the gauss1 wavelet base well, operates from a 1V supply and consumes less than 0.47 µW quiescent power.