A low-power wide-bandwidth fully differential operational amplifier with current re-using feedforward frequency compensation

A fully differential operational amplifier (op-amp) is described that simultaneously achieves low power consumption and wide bandwidth by employing current-reusing feedforward compensation scheme. In contrast to the conventional feedfoward frequency compensation, the newly developed scheme re-uses the bias current of the second stage of op-amp and therefore the power consumption is minimized. The op-amp designed in a 0.25/spl mu/m CMOS technology achieves 77dB DC gain, 870MHz unity gain frequency and 56/spl deg/ phase margin for 1pF load capacitance. The op-amp draws 1.8mA from a 2.5V supply.