This chapter mainly introduces the representative digital LDO (DLDO) structures, including shift register-based DLDO, coarse-fine-tuning DLDO, ADC-based DLDO, event-driven DLDO, computational DLDO, and digital-analog hybrid LDO. In the shift register-based DLDO section, we introduce the classic structure, adaptive frequency technique, and successive approximation recursive (SAR) DLDO. For the coarse-fine-tuning DLDO, we discuss its mechanism of balancing accuracy and transient response and introduce several classic examples. In ADC-based DLDO, we discuss voltage-domain quantizer, time-domain quantizer, and proportional-integral-derivative (PID) controller. In the event-driven DLDO section, we introduce the differences and advantages of event-driven and time-driven and discuss the challenges and corresponding technical points in the design of event-driven DLDO. Next, we introduce two computational DLDO control schemes: the charge and discharge algorithm, and the time-based exponential control. In the digital-analog hybrid DLDO section, we introduce four control schemes: passive analog-assisted (AA), active AA, digital-assisted, and analog-digital merged. Finally, we discuss the stability and reliability issues in advanced processes and large voltage difference conditions, with some solutions.