Multi-Stage LDO Regulator Power Sequencing with Gm Capacitor Control

The patent applies preliminary action by pre-charging the decoupling capacitors through controlled current sources before the LDO regulator operates. During power-up, current sources are activated to charge the large decoupling capacitors in advance, and during power-down, current sources discharge them rapidly. This preliminary charging/discharging action resolves the contradiction by enabling fast power transitions while maintaining the large capacitor values needed for high PSRR.

The patent applies dynamics by making the capacitor charging/discharging process controllable and dynamic rather than passive. Current sources with controllable magnitude are used to charge and discharge the decoupling capacitors at different rates depending on the operational phase. During normal operation, the capacitors provide stable filtering, but during power transitions, the current sources dynamically adjust to enable rapid voltage changes, thus resolving the contradiction between stability and speed.

The patent applies universality by designing current sources that serve multiple functions: they charge decoupling capacitors during power-up, discharge them during power-down, and can operate in parallel with the LDO regulator's normal operation. This multi-functionality reduces the need for separate dedicated charging/discharging circuits, thereby mitigating the increase in circuit complexity while maintaining the benefits of multi-stage configuration for high PSRR.