Input Dependent Voltage Regulator Charge Pump Dropout

The patent implements dynamic switching between two transistor configurations based on input voltage conditions. When input voltage is sufficient, the first transistor operates in saturation mode for LDO regulation. When input voltage drops below the dropout threshold, the circuit dynamically transitions to use the second transistor in triode mode as a current pass element, allowing the regulator to maintain output voltage across a wider input voltage range including below the original dropout point.

The patent changes the operating parameters of the transistor by switching between two different transistor elements (first and second transistors) with different characteristics. The second transistor is specifically designed to operate in triode mode as a current pass element, changing the effective drain-source resistance and allowing regulation to continue when the first transistor would be in dropout.

The patent segments the regulation function into two separate transistor paths: a first transistor for normal LDO operation in saturation mode providing stable regulation, and a second transistor for dropout compensation in triode mode. This segmentation allows each transistor to be optimized for its specific operating region, maintaining output voltage stability across the full range of input voltages including dropout conditions.

The second transistor acts as an intermediary current pass element that becomes active when the first transistor can no longer maintain regulation. This intermediary transistor provides the necessary current path when the primary regulation mechanism fails, ensuring continuous output voltage stability even when input voltage drops below the original dropout point.