Design and analysis of a quad-ferential ampilifer

This paper presents a design and analysis of a quad-ferential amplifier. A quad-ferential amplifier consists of four inputs, four outputs, and a V_OCM pin which controls the output common-mode voltage. It is similar to the differential amplifier in that it amplifies differences and rejects overall input common-mode. The transfer function shows that quad-ferential amplifier requires symmetry of feedback and gain resistors to approach its ideal behavior. Using a graphical approach the amplifier is compensated to drive a capacitive load of 50pF. The output current drive is designed for minimum load resistance of 150Ω. Statistical models are utilized in performing Monte Carlo simulations to evaluate offset voltage and common-mode rejection. These simulations show mean offset voltage of 265μV and a common-mode rejection of 126dB.