A gm/Id-Based Rapid Design Method for High-Bandwidth Capless LDOs with Fast Transient Response

This paper proposes a systematic design methodology for capacitorless low-dropout (LDO) regulators tailored for advanced CMOS processes, aiming to achieve high bandwidth and fast transient response that meet stringent performance requirements. A dynamic response model is first established to analyze the transient behavior of LDOs under varying load conditions. Based on this, a rapid operational amplifier design strategy incorporating the gm/Id methodology is proposed to optimize performance. The approach integrates key techniques such as pole-zero cancellation and feedback loop compensation to ensure system stability across a wide load range. A prototype LDO implemented in a 22 nm CMOS process delivered a stable 1 V output from a 1.8 V supply and maintains stability with only a 2.5 pF load capacitor. The simulation results validate the effectiveness of the method in minimizing undershoot and overshoot, as well as achieving a rapid steady-state response, highlighting its superiority in low-power, high-speed applications.