A Power-Efficient Linearized Open-Loop OTA Utilizing Reconfigurable Tail-Resistor Pair

This brief presents a power-efficient open-loop operational transconductance amplifier (OTA) topology for sensing applications. Reconfigurable tail-resistor (RTR) technology is proposed to achieve exceptional odd-order harmonic distortion while maintaining excellent energy-efficiency to meet the different application needs of sensors. The key to achieving this performance is the reconfigurability of resistors based on switches and the degeneration of resistors for the exponentiation of transistors in sub-threshold region. Fabricated in a 180-nm CMOS technology, the prototype linearized OTA achieves −82-dB third harmonic suppression for an input signal of 100-mV $_{\mathrm{ in-diff}}$ employing the pseudo-differential degeneration configuration, and exhibits −77.6-dB linearity in the common-mode degeneration topology. And it only dissipates 3.6- $\mu \text{W}$ from 1.35-V/1.8-V supply.