0.9 V low-power switched-opamp switched-capacitor bandpass filter for electroneurography acquisition systems

A 0.9 V fully differential switched-opamp-based sixth-order switched-capacitor bandpass filter, which has frequency response centred at 1.118 kHz with a Q of 0.235 and power saving by a proposed low-power biquad structure, is designed for electroneurography acquisition systems. It is implemented in a 0.18 mum CMOS technology with a normal threshold voltage of 0.48 V. The measured peak signal-to-noise ratio is 52 dB at 1 kHz sinusoid wave with input amplitude of 1 V_pp. In addition, the measured power-supply rejection ratio and common-mode rejection ratio are >40 dB in the desired bandwidth and have peak values of 70 and 67 dB, respectively. A dynamic range of 50 dB for total harmonic distortion of 3% is obtained while dissipating 262 muW and occupying a chip area of 0.35 mm².