An Ultra High CMRR Low Voltage Low Power Fully Differential Current Operational Amplifier (COA)

Abstract: this paper presents a novel Fully Differential (FD) ultra high Common Mode Rejection Ratio (CMRR) Current Operational Amplifier (COA) with very low input impedance. Its FD structure that attenuates common mode signals over all stages grants ultra high CMRR and Power Supply Rejection Ratio (PSRR) that makes it suitable for mixed mode and accurate applications. Its performance is verified by HSPICE simulations using TSMC 0.18 μm CMOS technology and ±0.75 V supply voltage that indicate such outstanding results of 81.1 dB gain, 298 MHz gain-bandwidth product, 64º phase margin, 28.2 mΩ input impedance, 159 dB CMRR and PSRR+/PSRR- of 174 dB/163 dB all at low power consumption of 0.302 mW. To study the robustness of the COA against technology and get such results close to measurement, Monte Carlo analysis is applied on both prelayout and post layout simulations of the design. The results are as; 73.29 dB and 2.07 MHz, 1.92 Ω, and150.35 dB for Ai magnitude and bandwidth, Ri, and CMRR, respectively, in pre-layout case while change to; 66.58 dB and 1.44 MHz, 11.07 Ω, and 147.10 dB, for the same arrange, in post layout case. These measurement-like results thus, prove excellent practical performance of the proposed COA.