A Versatile High-Swing G_m -C Filter with Process and Temperature Invariant Bandwidth and Gain for Neuro-Potential Signal Conditioning and Recording

A novel first order ultra low power, bandpass G _m -C filter with rail to rail output in 180 nm CMOS technology is presented. The proposed filter is suitable for multichannel neuro-potential signal acquisition and operates at 1.8 V supply voltage. The presented G _m -C filter takes advantage of an ultra low-power constant G _m /C circuit consuming only 850 nA and a constant G _m circuit, which leads to constant gain and bandwidth performance. Constant G _m uses a novel process and temperature tolerant on-chip resistor. The on-chip resistor has process variation of ±6.5% and temperature variation of ±1.1% for a temperature range of 0 °C to 100 °C. Constant G _m module draws 76 μA from 1.8 V supply. Total current consumption of the bandpass G _m -C filter is 4.03 μA. The proposed filter has a tunable bandwidth from 160 Hz to 7.2 kHz and exhibits input referred noise voltage of 4.17 μV for a bandwidth of 10.2 kHz. The filter provides output voltage swing of 1.55 V and occupies area of 360 μm*310 μm.