Modified recycling folded cascode OTA with enhancement in transconductance and output impedance

Authors: SUDHEER RAJA VENISHETTY, KUMARAVEL SUNDARAM

Abstract: A modified recycling folded cascode (MRFC) operational transconductance amplifier (OTA) for achieving high DC gain, slew rate, and unity gain bandwidth (UGB) is proposed in this paper. Positive feedback is adopted to enhance DC gain and unity gain bandwidth. The proposed MRFC OTA is compared with conventional folded cascode (FC), recycling folded cascode (RFC), and other OTAs existing in the literature. Three OTAs, FC, RFC, and MRFC, are realized and implemented using the UMC 180 nm CMOS process for the same bias current of 300 $\mu$A. The designs are simulated in the Cadence Spectre Environment. From the simulation results, it may be noted that the proposed amplifier achieves a gain of 76.24 dB and unity gain bandwidth of 74.7 MHz with an input referred noise and slew rate of 139.2 $\mu V_{rms}$ and 64.05 V/$\mu$s respectively. The proposed amplifier occupies an area of 2760 $\mu m^{2}$.

Keywords: Amplifiers, CMOS, input referred noise, recycling folded cascode, slew rate, unity gain bandwidth, transconductance

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