A 0.087 fs FOM Current-mirror-based Analog-assisted Digital LDO with Vo Ripple Optimization

This paper proposes a current-mirror based analog-assisted (CBAA) digital low-dropout regulator (DLDO) that achieves a fast transient response and output voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{V}_{\mathrm{O}})$</tex> ripple optimization. It features less than 1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{mVV}_{\mathrm{O}}$</tex> ripple at 200 mA load current <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{I}_{\mathrm{L}})$</tex> and 106 mV undershoot in load transition. Fabricated using 28 nm CMOS process, the CBAA DLDO shows a superior figure-of-merit (FOM) of 0.087 fs among low input voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{V}_{\text{IN}})$</tex> DLDOs.