A Sub-µW Tuneable Switched-Capacitor Amplifier-Filter for Neural Recording Using a Class-C Inverter

A two stage sub-µw inverter-based switched-capacitor amplifier-filter is presented which is capable of amplifying both spikes and local field potentials (lfp) signals. here we employ a switched capacitor technique for frequency tuning and reducing of 1/f noise of two stages. the reduction of power consumption is very necessary for neural recording devices; however, in switched capacitor (sc) circuits ota is a major building block that consumes most of the power. therefore an ota-less technique utilizing a class-c inverter is employed that significantly reduces the power consumption. a detailed analysis of noise performance for the inverter-based sc circuits is presented. a mathematical model useful for analysis of such sc integrators is derived and a good comparison is obtained between simulation and analytical technique. with a supply voltage of 0.7v and using 0.18 µm cmos technology, this design can achieves a power consumption of about 538 nw. the designed amplifier-filter has the gains 18.6 db and 28.2 db for low pass only and cascaded filter, respectively. by applying different sampling frequencies, the filter attains a reconfigurable bandwidth.