Stability and transient response enhancement techniques for low-dropout regulators

Low-dropout regulators (LDOs) are one of the most important power management modules for providing clean supply voltages in all portable devices. This tutorial first describes the limitations of a generic CMOS LDO on the stability and the load transient response. Then, stability of the state-of-the-art LDOs with intermediate driver stages is discussed. Finally, a LDO design example using impedance attenuation (BIA) technique is presented. The BIA technique is able to reduce the number of low-frequency poles of the LDO without using any low-frequency zero, thereby improving the stability and the load transient response simultaneously.