The improvement of gain and bandwidth by using positive feedback infully differential amplifier

Operational amplifiers due to the large applications in many analog and digital circuits are very significant. The most important requirements in operational amplifiers are gain, bandwidth and power consumption. Since the all of circuit parameters are not desired and some of them are contradictory to another one, then the applied design must be a compromise between these parameters, including gain and bandwidth thatare against each other. In this paper, fully differential two stages amplifier by applying positive feedback has been used to solve mentioned problems. Positive feedback can increase the amplifier gain and bandwidth with no significant changes in amount of power consumption. Proposed method has utilized 0.18um technology for CMOS transistors. Simulation results show that the amplifier gain and bandwidth are obtained 110.2dB and 592.56 MHz respectively. Also power consumption is 1.56 mw.