Design of Low Power Folded Cascode Current Mirror CMOS OTA and Implementation of 2nd Order Gm-C IF Filter with Analysis of S-Parameter

Abstract

This paper deals with design and optimization of a cascode current mirror folded cascode operational transconductance amplifier is done in order to optimize MOS transistor sizing. The design of folded cascode OTA, which works for frequencies that lead to a base band circuit design for RF application, is based on transistor sizing methodology and Simulation results are performed using SPICE software and BSIM3V3 model for CMOS 0.18μm process, show that the designed folded cascode OTA has a 52dB DC gain and provides a Unit gain bandwidth of around 400MHz. In this paper the design of CMOS Gm-C 2nd order Biquad Filter implementation using OTA, operating at center frequency 70MHz.The simulated performance shows that the filter provides a Q of 23. The filter can be operated at center frequency of 70MHz under 1.8V power supply and is suitable for intermediate frequency (IF) range in most of the wireless systems operating at 900MHz.

Keywords: Folded cascode OTA, gm/ID methodology, active filters, S-parameter, Smith Chart, (OTA-C) filters