Design and analysis of modified recycling folded cascode amplifier with improved transconductance and slew rate

摘要

To improve the transconductance of operational transconductance amplifier (OTA), various architectures namely recycling folded cascode (RFC), Improved recycling folded cascode (IRFC), modified recycling folded cascode (MRFC) and high recycling folded cascode (HRFC) are existing in the literature. In this paper, further improvement in the transconductance of MRFC OTA can be achieved by shorting two nodes of its current mirror and is proposed as high modified recycling folded cascode (HMRFC) amplifier. The performance of the proposed HMRFC OTA is compared with the existing state of art OTAs. To validate the progressions in the specified parameters, recycling folded cascode (RFC), modified recycling folded cascode (MRFC) and high modified recycling folded cascode (HMRFC) OTAs are realized and implemented in UMC 180 nm process technology using Cadence Spectre for a bias current of 1.2 mA. Simulation results indicate that the proposed amplifier exhibits a DC gain of 79.47 dB, the slew rate of 194.2 V/μSec, UGB of 285.85 MHz and phase-margin of 77.12o for a load capacitance of 5 pF and also observed that the CMRR and FoMs of the proposed amplifier are better by a factor of 1.3 and 1.5 in comparison to RFC, and by a factor of 1.27 and 1.41 in comparison to MRFC OTAs respectively.