Design of a fully differential controlled gain open-loop wideband amplifier with common-mode feedback

Abstract

This project designs a Fully-Differential Controlled-Gain Open-Loop Wideband Amplifier with Common-Mode Feedback with 55nm Global Foundry Process. The specifications of this circuit are being verified through rigorous simulation by varying process corners, supply voltage and temperature. Based on the pre-layout simulation result, this circuit achieve an open-loop gain of 18.48dB and a unity gain bandwidth of 827MHz with a load capacitor of 92.7784fF on each side. Meanwhile, the output common-mode voltage is controlled by the CMFB circuit to stay at 0.75V while achieving a minimum output voltage of 0.08366V and a maximum voltage of 1.421V. The is also able to reject the power supply noise at a rate of PSRR+ = 214.3471dB and PSRR- = 251.67dB, it can also reject common mode noise with CMRR = 307.0127dB and provide a total harmonic distortion of -39.41dB. Finally, the power dissipation of this circuit when the supply voltage is 1.5V is 0.7204mW. Also, layout is drawn for this circuit and post-layout simulation is also being performed. This circuit has a layout area of 26.137μm×32.084μm.