Design of Low Voltage CMOS OTA Using Bulk-Driven Technique

Background/Objectives: The main objective was to design a CMOS Operational Transconductance Amplifier (OTA) for biomedical applications and high speed transmission with an operating voltage 0.4 V. Methods/Statistical Analysis: In this paper we have proposed an OTA using bulk driven technique. The transistors are working in weak-inversion. The design was simulated using conventional transistors. The technique employed was source degeneration technique with positive feedback for enhancement of the transconductance. Findings: The proposed OTA obtains a DC gain (Ao) of 26 dB, a Gain-Bandwidth Product (GBW) of 750 MHz, Slew Rate (SR) of 3.7 V/μs, a Phase Margin (PM) of 98°, DC offset of 2.2 mV and a power dissipation of 250 μW under no load condition. The proposed OTA is simulated in 90-nm CMOS technology using Cadence EDA software. Voltage to current (V/I) convertor based on proposed OTA is also simulated in 90-nm CMOS technology. The simulated results confirm rail to rail operation with the transconductance of 26 μS and bandwidth upto 40 MHz. The overall power consumption is also very less which makes it useful for low power portable applications. Applications/Improvements: The OTA proposed in this paper can be employed in low power biomedical and sensor applications. The gain could be increased for the proposed OTA as it is less and could be enhanced.