This 65 nm power management module with a 1.2 V low-voltage PWM controller aims to integrate with an ultra-wideband (UWB) system to get high efficiency and compact size. The on-chip pre-regulator with power conditioning circuit provides a constant and noiseless supply voltage with high conversion efficiency. Thus, the voltage variation of the battery has less effect on the low-voltage PWM controller. Besides, the proposed compensation enhancement multistage amplifier (CEMA) increases system loop gain and stabilizes the system through the multistage structure suitable for low voltage operation. Moreover, the CEMA utilizes two small on-chip capacitors (5 pF and 2 pF) to stabilize the power management module. Unlike the conventional method, no additional off-dop components are needed to compensate this power management. With excellent line/load transient response, the proposed power management has the highest efficiency about 92% and 0.995 mm2 silicon die area adequate to the SoC application.