Design of highly linear tunable CMOS OTA

An analytical method based on the standard square-law MOS model for the design of a highly linear, fully differential CMOS operational transconductance amplifier (OTA) is presented. The proposed circuit implementation combines a cross-coupled quad cell with a source-coupled differential pair, linked by current mirrors. Improved linearity of the OTA over a large tuning range is obtained. SPICE simulations show that for /spl plusmn/2.5-V, power supply power consumption is 6.6 mW, total harmonic distortion (THD) at 2.5 V/sub pp/ is less than 0.2%, and the dynamic range is 77 dB.