| The development of the portable devices impulses the progress of the power management products. The power management integrated circuit has many advantages, such as high integrity, high performance to price ratio, the most simple outer circle circuit, and high-efficiency power supply etc. The LDO(Low Dropout Regulator)becomes more and more important, because it is lower in dropout voltage, smaller in size, lower in power dissipation and many other advantages. It occupies one of the most important fields in voltage converter productions.The thesis focuses on the design of an on chip DC-DC converter which is a low dropout voltage regulator and can be used in portable device. The design contains a bandgap reference, error amplifier, pass element feedback resistors network etc. To keep the IC reliable, the design also contains overheat protection circuit and over-current protection circuit. All the measures protect the chip self's security and also protect sub-circuit's security. A dynamic leakage circuit is added to improve the transient response of the LDO. A dynamic leakage access is provided and little current is consumed when it is in static state. The thesis introduces all blocks in details.It has the wide input range (3V~5.5V). The output voltage is 2.5V. The temperature range is from-40℃to100℃and good temperature characteristic is ensured. When the load current is 100mA, the dropout voltage is 300mV and the quiescent current is 4.7μA.Each sub-circuit and the whole circuit are simulated with Spectre. It is designed by using NEC 0.25μm standard CMOS technology. The area of the whole layout is 480μm×330μm. Extract the parasitical parameter and the post simulation is carried out with Hspice. Simulation result indicates the whole system meets the requirement of capability and achieves the design target. |
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