Design of 1 V Operating Fully Differential OTA Using NMOS Inverters in 0.18 μm CMOS Technology

This paper presents a 1 V operating fully differential OTA using NMOS inverters in place of the traditional differential pair. To obtain high gain, a two-stage configuration is used in which the first stage has feedforward paths to cancel the common-mode signal, and the second stage has common-mode feedback paths to stabilize the output common-mode voltage. The proposed OTA was fabricated by an 0.18 mu m CMOS technology. Measured gain is 40dB and GBW is 10 MHz, in addition to differential output voltage swing of 1.8 Vp-p. It is confirmed that the proposed OTA can operate from 1 V power supply and has very large output swing capability even in a 1 V operation. The proposed OTA configuration contributes to a solution to the low power supply voltage issue in scaled CMOS analog circuits.