Fully Integrated, Low Drop-Out Linear Voltage Regulator in 180 nm CMOS

This paper presents a capacitor-free low dropout (LDO) linear regulator based on a dual loop topology. The regulator utilizes two feedback loops to satisfy the challenges of hearing aid devices, which include fast transient performance and small voltage spikes under rapid load-current changes. The proposed design works without the need of a decoupling capacitor connected at the output and operates with a 0-100 pF capacitive load.

The design has been taped out in a 0.18 µm CMOS process. The proposed regulator has a low component count, area of 0.012 mm2 and is suitable for system-on-chip integration. It regulates the output voltage at 0.9 V from a 1.0 V - 1.4 V supply. The measured results for a current step load from 250-500 µA with a rise and fall time of 1.5 µs are an overshoot of 26 mV and undershoot of 26 mV with a settling time of 3.5 µs when CL between 0-100 pF.

The proposed LDO regulator consumes a quiescent current of only 10.5 µA. The design is suitable for application with a current step edge time of 1 ns while maintaining ∆Vout of 64 mV.