AC Boosting Compensation with Zero Cancellation for Multistage Amplifiers

This paper presents a high-gain wide-bandwidth multistage amplifier for sub-fV applications. This serves as an error amplifier for low-drop-out (LDO) voltage regulators. The amplifier is stabilized using an AC gain boosting scheme along with RHP zero cancellation (ACBZC). An AC multipath is added to the internal stage of the conventional three stage amplifier, which improves significantly the gain-bandwidth (GBW) product without increasing the total power consumption substantially. Also, a right half plane (RHP) zero cancellation using multipath zero cancellation technique is proposed to further improve the GBW by 18%. A three stage amplifier has been designed using 90-nm CMOS process and is simulated using a 1 V power supply. Simulation results shows that a DC gain >90 dB, GBW of 40 MHZ with 60° phase margin and a power of 435 μW can be achieved with a load capacitance up to 10 pF.