Variable-Offset LDO for Stable SAR ADC Reference Voltage

The reference voltage generator is divided into multiple segments: a main reference voltage generator, a peak current generator, and a capacitor. The peak current generator operates only during specific time periods when high current is needed, while the capacitor maintains voltage stability during other periods. This segmentation allows the system to achieve high reference voltage stability without continuously operating high-current components, thereby reducing overall device complexity and power consumption.

The system employs periodic action by controlling the peak current generator to operate only during specific time periods (e.g., during sampling phases) rather than continuously. The capacitor is charged during these periodic high-current periods and then maintains the reference voltage during intermediate periods. This periodic operation allows the use of a smaller capacitor compared to continuous operation, significantly reducing the area occupied by the capacitor while maintaining reference voltage stability.

The capacitor serves as an intermediary energy storage element between the peak current generator and the ADC. During high-frequency switching operations, the capacitor supplies the required peak current to the ADC, acting as a buffer that isolates the reference voltage generator from direct current demands. This intermediary approach allows the ADC to operate at high speeds while the reference voltage generator maintains stable output, preventing distortion caused by direct coupling of peak current demands.