An FVF-LDO with Differential EA and Push-Pull Super Source Follower for Fast Transient Response

This article presents a fully integrated flipped voltage follower (FVF) based low-dropout (LDO) regulator with enhanced transient response for noise-sensitive circuits. Focusing on shorter overshoot response and recovery time, a dual-loop FVF LDO with differential error amplifier (EA) and a push-pull super source follower (PPSSF) is proposed. This work, designed in a 65 nm CMOS process, with 1.2 V input and 1 V output, exhibits a quiescent current ($\text{I}_{\text{Q}}$) of $110 \ \mu \text{A}$. The load current ILOAD ranges from 0 to 20 mA. The circuit achieves 1 ns response time and 122 ns recovery time for both voltage overshoot and undershoot. Furthermore, with 50 dB of DC gain, the LDO reaches a low-frequency power supply rejection (PSR) of -50 dB and the worst full-spectrum PSR of −5.6 dB at 20 mA ILOAD with a 300 pF on-chip capacitor.