An Ultrafast Adaptively Biased Capacitorless LDO With Dynamic Charging Control

This brief presents a current-efficient fully integrated low-dropout regulator (LDO) for system-on-a-chip applications. A common-gate error amplifier with high bandwidth and slew rate is proposed to reduce the output voltage spike and the response time of the LDO greatly. In addition, the loop employs a direct dynamic charging technique to enhance load-transient responses by directly detecting voltage variations through a capacitive coupling high-pass filter. The circuit has been implemented in a 0.35-mu m standard complementary metal-oxide-semiconductor process and occupies an active chip area of 0.064 mm(2). Experimental results show that it can deliver a load current of 100 mA at a dropout voltage of 150 mV. It only consumes a quiescent current of 7 mu A at light loads and can recover within 0.15 mu s, even under the maximum load current change. Consequently, a faster and more accurate capacitorless LDO can be achieved.