Ricerc@Sapienza

A low-power 6th-order Butterworth bandpass filter has been designed for the front-end of an integrated neural recording system. The passband has been set to 250-500Hz to allow recording the fast ripple (FR) associated with epileptic seizure onset and filter out all other undesired components of the neural signals. The filter is composed of 3 Gm-C biquad stages. Low-power operation is achieved by biasing the MOS devices in the sub-threshold region, and using a dual power supply of ±0.5V.

In this work, we present a low-power 2nd order band-pass filter for neural recording applications. The central frequency of the passband is set to 375Hz and the quality factor to 5 to properly process the neural signals related to the onset of epileptic seizure, and to strongly attenuate all the out of band biological signals and electrical disturbances. The biquad filter is based on a fully differential Tow Thomas architecture in which high-valued resistors are implemented through switched high-resistivity polysilicon resistors.