An LDO With 4.8-nA Quiescent Current and Improved Transient Response Within a 50-mA Load Current Range

Low-power systems, such as IoT devices, require low- dropout regulators (LDOs) featuring 1) minimized quiescent current (${I_{\mathrm{Q}}}$) to extend battery usage time, 2) high stability over a wide load range, and 3) fast transient response. This paper presents an LDO fulfilling these requirements through a variable capacitance tracking zero compensation (VCTZC) scheme. Meanwhile, it extends the bandwidth in heavy-load conditions, reducing the output voltage overshoot under a step-down transient response. Furthermore, via an adaptive biasing scheme, it retains transient enhancement while reduces${I_{\mathrm{Q}}}$at the steady state. Designed with a 65-nm CMOS process, the proposed LDO consumes a 4.8-nA${I_{\mathrm{Q}}}$and provides a maximum 50-mA load current. The output undershoot is 204mV when the load current transitions from 5$\mu$A to 50mA with a 2-ns edge time.