A Novel Class-AB Buffer for LDOs with High Accuracy and Fast Transients

This paper presents a low dropout (LDO) regulator that employs a novel class AB buffer with series-shunt feedback to drive the power stage. A design example validates the proposed topology: an LDO implemented in a standard CMOS process maintains the output voltage at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1. 5\mathrm{V}+/-3\%$</tex>, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$+/-45\text{mV}$</tex> including responses to fast <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$($Tedge $=100\text{ns})$</tex> jumps of the supply varies between 1.8V and 2.5V, and of the load current between zero and 100mA, as well as temperature variations from −40°C to125°C.