A BICMOS WIDE-BAND OPERATIONAL-AMPLIFIER WITH 900 MHZ GAIN-BANDWIDTH AND 90 DB DC GAIN

A fully differential operational amplifier has been designed and fabri cated for a novel high resolution and high frequency analog-to-digital converter(>12-bit). The amplifier mainly consists of folded cascode s tructure with current source as output loads and common-mode feedback circuits. The technique of feedforward compensation is used in order t o improve the settling time and gain bandwidth (GBW) of this amplifier . This amplifier is integrated in 0.8 mm BiCMOS process with an active die area of 0.1 mm(2). The DC gain of this amplifier is 90 dB. The GB W and phase margin of this amplifier is 900 MHz and 47 degrees, respec tively. The power dissipation is minimized by using BiCMOS technology and is about 25 mW for 2 pF load capacitance. This level of performanc e is competitive with CMOS and BiCMOS operational amplifier circuits p reviously reported by nearly two orders of magnitude.