Leakage compensation scheme for ultra-high-resistance pseudo-resistors in neural amplifiers

Although MOS-based pseudo-resistors are capable of achieving the ultra-high resistance required to design small-area neural amplifiers, they suffer from substrate leakage currents which become dramatically higher when the devices are exposed to light. This can cause unwanted amplifier offsets and hinders the usability of these devices in the emerging optoelectrical neural applications. A solution is proposed to compensate the pseudo-resistor leakage current using a dummy deep N-well device. Experimental results show that neural amplifiers implemented with the compensated pseudo-resistor become more robust to photo-induced leakage currents.