Design of capacitor-less LDO regulator with SCR-based ESD protection using dual push-pull stage

Abstract

ABSTRACT The external capacitors of conventional LDO (Low Drop Out) regulator have a function to improve the transient response characteristics affected by the overshoot and undershoot. However, the LDO regulator proposed in this study is replaced the function of the external output capacitor with a dual push-pull stage and is achieved a fast transient response by a newly added control path to replace the function of the capacitor removed along with the existing feedback path. The proposed LDO regulator can also be provided the improved ESD (Electro Static Discharge) robustness characteristics by applying the SCR (Silicon Control Rectifier)-based ESD (Electro Static Discharge) protection device embedded into the output node and power line. The LDO regulator with dual push-pull circuit proposed in this study was operated at a maximum load current of 100 mA, an output voltage of 3 V, and an input voltage range of 3.3 ~ 4.5 V. As a result of the measurement, an undershoot voltage of 110 mV and an overshoot voltage of 123 mV were maintained when a load current of 100 mA was applied. Further, the ESD robustness characteristic of HBM is guaranteed at 8kV or higher.