Power management has had an ever increasing role in the present electronic industry.Battery powered and handheld applications require power management techniques to extend thelife of the battery and consequently the operation life of the device. Most systems incorporateseveral voltage regulators which supply various subsystems and provide isolation among suchsubsystems. Low dropout (LDO) voltage regulators are generally used to supply low voltage,low noise analog circuitry. Each LDO regulator demands a large external capacitor, in the rangeof a few microfarads, to perform. These external capacitors occupy valuable board space,increase the IC pin count, and prohibit system-on-chip (SoC) solutions.The presented research provides a solution to the present bulky external capacitor LDOvoltage regulators with a capacitor-less LDO architecture. The large external capacitor wascompletely removed and replaced with a reasonable 100pF internal output capacitor, allowingfor greater power system integration for SoC applications. A new compensation scheme ispresented that provides both a fast transient response and full range ac stability from a 0mA to50mA load current. A 50mA, 2.8V, capacitor-less LDO voltage regulator was fabricated in aTSMC 0.35um CMOS technology, consuming only 65uA of ground current with a dropoutvoltage of 200mV.Experimental results show that the proposed capacitor-less LDO voltage regulator exceedsthe current published works in both transient response and ac stability. The architecture is alsoless sensitive to process variation and loading conditions. Thus, the presented capacitor-lessLDO voltage regulator is suitable for SoC solutions.
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