8.3 A 200mA digital low-drop-out regulator with coarse-fine dual loop in mobile application processors

A modern mobile application processor (AP) requires a variety of power voltage levels, which increases the number of external capacitors around the mobile AP. This is because the supply PCB routes from the power management IC (PMIC) to the AP have parasitic inductors. The parasitic inductors introduce ripples on power voltage lines. Therefore, external capacitors are required on the PCB routes between the PMIC and the mobile AP. To reduce the number of external capacitors, one power voltage level from the PMIC is converted into a variety of power voltage levels inside the mobile AP. This both reduces external capacitors as well as the number of power pins on the mobile AP and simplifies PCB routes. For such reasons, integrated low-dropout regulators (LDOs) are preferred in mobile APs.