Linear Voltage Regulators

Summary

Linear voltage regulators convert an input voltage into a lower output voltage. The lower the dropout, the lower the input voltage that can be tolerated. Since dropout is essential, a linear regulator is often referred to as Low‐Dropout Regulator or LDO in its widely used short form. This term is used to distinguish regulators with higher dropout voltage, which have been around in the early days. Power efficiency is an important DC parameter, like in all power management circuits. In linear regulators, the current efficiency is another DC parameter. Capacitor‐Less LDOs usually install multi‐stage error amplifiers to achieve high gain bandwidth. The error amplifier's power supply rejection (PSR) plays an important role in the PSR of the entire LDO. Understanding the noise mechanisms in the LDO is essential to achieve a clean output voltage with minimum noise. The shunt regulator makes an excellent initial bias for any voltage converter.