Design of an ultra low voltage VDBA using bulk driven quasi floating gate techniques for high order biosignal processing

Abstract This paper presents a high-performance ultra-low-voltage (ULV) voltage differencing buffered amplifier (VDBA) operating from a 0.5-V supply. Consisting of an operational transconductance amplifier (OTA) followed by a voltage follower (VF), the proposed VDBA combines bulk-driven (BD) and bulk-driven quasi-floating-gate (BD-QFG) MOS techniques to overcome threshold-voltage limitations and enhance the performance of subthreshold circuits. Designed in the Cadence Virtuoso environment using the TSMC 65-nm CMOS process, the proposed VDBA consumes only 370 nW and occupies 0.022 mm 2 area. Its applicability is demonstrated through a fifth-order Butterworth low-pass filter for ECG signals, achieving an electronically tunable cutoff frequency from 73.65 to 557.8 Hz, 1.1% THD for a $$\:100{\text{}\text{mV}}_{\text{p-p}}$$ input signal, and a 44 dB dynamic range. Monte Carlo and PVT analyses confirm the robustness of the proposed design, while experimental implementation using the commercially available LM13700 further validates the proposed filtering approach.