Design And Research Of Portable Devices' Power Management IC

The fast growing demanding of portable and battery-operated electronics systems has driven the efforts to reduce complexity of IC or to improve the efficiency of these electronics equipments. Power management has had an ever increasing role in the present electronic industry. Regulators are essential for most electrically powered systems which include the prevalent portable equipments. Regulators are required to reduce the voltage variation of the battery. Battery powered and handheld applications require power management techniques to extend the life of the battery and consequently the lifetime of the device. Most systems incorporate several voltage regulators which supply various subsystems and provide isolation among such subsystems. Low dropout (LDO) voltage regulators are generally used to supply low voltage, low noise analog circuitry. Each LDO regulator demands a large external capacitor, of a few microfarads, to operate. These external capacitors occupy valuable board space, increase the number of pins of an IC, and prohibit system-on-chip (SoC) solutions.The presented research provides a solution to the present bulky external capacitor LDO voltage regulators with a capacitor-less LDO architecture. The large external capacitor was completely removed and replaced with a reasonable 100pF internal output capacitor, allowing for greater power system integration for SoC applications. In addition, system-on-chip designs with on-chip and local LDOs can reduce both board and external pins significantly. A new compensation scheme is presented that provides both a fast transient response and full range ac stability from OmA to 50mA loading current. A 50mA,2.8V, capacitor-less LDO voltage regulator was simulated in a SMIC 0.35um CMOS technology, consuming only 65uA of ground current with a dropout voltage of 200mV.The Spectre simulator's emulation results show that the proposed capacitor-less LDO voltage regulator exceeds the current published works in both transient response and ac stability. The architecture is also less sensitive to process variation and loading conditions. Thus, the presented capacitor-less LDO voltage regulator is suitable for portable devices'SoC solutions.