Constant Tera-ohm Pseudo-resistor Over Wide Dynamic Range

This work presents the design of a constant, programmable and extremely high (Tera ohm) MOS pseudo-resistor over a wide dynamic range of ±0.6 V based on MOS transistors operating in the weak inversion region. The major challenge faced by the circuit designers in designing high resistance pseudo-resistor is the linearity problem and it is resolved in this work. The proposed pseudo-resistor is utilized as a feedback resistor in the second stage of the two-stages bio-medical amplifiers in the portable bio-detection system. By controlling the resistance of this pseudo-resistor, the lower cut-off frequency of the amplifier is automatically adjusted and thus allowing the detection of the small frequency range. Simulations in LT-spice using 130 nm CMOS technology under ±0.6 V supply voltage are performed to validate the realization of the extremely high resistance and its application.