Ultra Low Power Fully Differential Double Recycling Current Mirror OTA for Biomedical Applications

Abstract

AbstractThis paper presents a low-voltage low-power fully differential bulk-driven operational transconductance amplifier (OTA). The input core of this OTA is based on the double recycling structure where input PMOS are bulk-driven. The flipped-voltage-follower adaptive biased input differential pairs operating in class AB mode ensures dynamic current enhancement along with increased slew rate. This OTA also incorporates partial-positive feedback structure at the current mirror load thus enhancing the effective transconductance. Upon simulation, the proposed OTA provided DC gain of 81.4 dB, unity gain frequency of 27.2 kHz, and phase margin of 71°. It utilizes ±0.25 V of dual power supply and dissipates 45 nW. These results validate its effectiveness as for low-voltage, low-power applications for low-frequency signal processing. Process corner simulations were also performed to evaluate the robustness of the proposed OTA’s low-frequency voltage gain, unity gain frequency, and phase margin, against process variations. A SIMO biquad filter is also realized using the proposed OTA. This OTA is designed and simulated using UMC 180 nm standard CMOS process technology.KeywordsLow-powerLow-voltageSubthresholdFully differential OTA