A low-voltage, low quiescent current, low drop-out regulator

摘要

The demand for low-voltage, low drop-out (LDO) regulators isnincreasing because of the growing demand for portable electronics, i.e.,ncellular phones, pagers, laptops, etc. LDO's are used coherently withndc-dc converters as well as standalone parts. In power supply systems,nthey are typically cascaded onto switching regulators to suppress noisenand provide a low noise output. The need for low voltage is innate tonportable low power devices and corroborated by lower breakdown voltagesnresulting from reductions in feature size. Low quiescent current in anbattery-operated system is an intrinsic performance parameter because itnpartially determines battery life. This paper discusses some techniquesnthat enable the practical realizations of low quiescent current LDO's atnlow voltages and in existing technologies. The proposed circuit exploitsnthe frequency response dependence on load-current to minimize quiescentncurrent flow. Moreover, the output current capabilities of MOS powerntransistors are enhanced and drop-out voltages are decreased for a givenndevice size. Other applications, like dc-dc converters, can also reapnthe benefits of these enhanced MOS devices. An LDO prototypenincorporating the aforementioned techniques was fabricated. The circuitnwas operable down to input voltages of 1 V with a zero-load quiescentncurrent flow of 23 ΜA. Moreover, the regulator provided 18 and 50 mAnof output current at input voltages of 1 and 1.2 V, respectively