A new linearization technique for a CMOS differential amplifier using bulk-driven weak inversion MOS transistors

A new CMOS differential amplifier using MOS transistors in weak inversion is presented. Because of the exponential characteristic of a MOS transistor in the subthreshold region, an original linearization technique based on a parallel connection of two differential stages opposite excited and different polarized is implemented. The canceling of the third-order term from the output voltage expression allows obtaining a reduction of the distortion coefficient with about an order of magnitude. The current consumption of the circuit is very small due to the subthreshold operation of transistors, making it compatible with low-power designs. The SPICE simulation confirms the theoretical estimated linearity improvement.