Highly Accurate Subthreshold Four Quadrant Multiplier for Biomedical Teager Energy Operator Circuits

The paper presents a fully CMOS subthreshold exponential circuit and its use in a four-quadrant multiplier targeted for Teager Energy Operator (TEO) based portable biomedical systems. The proposed circuits are operable with balanced input-differential output signals at both 1.2 V and 0.6 V supplies. The multiplier is simulated using 90nm CMOS process of the BSIM4v4.3 model in LTSpice. The input dynamic range of the realized multiplier is ±60 mV at 1.2 V and ±40 mV at 0.6 V with a maximum non-linear deviation under 5.9% and 2.6% respectively. It's Total Harmonic Distortion (THD) is under 0.3558% and 0.2159% while the maximum bandwidth achieved is 837.5293 kHz and 639.7348 kHz respectively. The exponential circuit achieves a low static power consumption of 33.0615 nW at 1.2 V and 6.5329 nW at 0.6 V enabling the realization of ultra-low-power multipliers targeted at high sensitivity and low distortion portable biomedical devices.