Low voltage fully differential OTA using DTMOS based self cascode transistor with slew-rate enhancement and its filter application

Abstract

In this work, low-voltage high-performance, fully differential current mirror Operational Transconductance Amplifiers (OTAs) are designed using DTMOS and asymmetric threshold voltage self cascode structure. Additionally cross drain coupled positive feedback and auxiliary slew-rate enhancement (SRE) technique are employed to improve the gain and slew-rate of proposed circuits. The proposed-I OTA (OTA-1) utilizes the dynamic threshold metal oxide semiconductor (DTMOS) technique which operates at low supply voltage and provides enhanced performance. However, the asymmetric threshold voltage self cascode structure used in proposed-II OTA (OTA-2) further improves the gain and other parameters. The proposed OTAs operate at ± 0.4 V dual power supply. The open-loop gain for the OTA-1 and OTA-2 is obtained as 73 dB and 82 dB with 10.04 μW and 10.77 μW power consumption, respectively. It offers enhanced slew-rate and improved GBW than the conventional OTA. Moreover, it gives high CMRR as 216 dB and 250 dB for the OTA-1 and OTA-2 respectively. The universal biquad voltage-mode filter has been realized using proposed OTAs. All simulations are performed using Mentor Graphics Eldo simulation tool with TSMC 0.18 μm process parameters. To validate the robustness of proposed OTAs, Monte Carlo analysis and corner analysis have been performed.