High-performance LDO Based On VCCS Compensation

In recent years,Power Management IC are widely used in digital signal processor (DSP), PDA, MP3player.And the power management chip LDO regulator, due to its simple structure and high stability,the LDO regulator occupy a large share in the market,and it is the most mainstream power chip.Although the domestic demand for power management chip,but not high demand for domestic chip,The reason is that the stability of the domestic chip worse than foreign chips.Because the high price of imported chips.If the domestic chip can have a good performance,that will be able to substitute the foreign high-price products, and change the market structure.It is necessary to develop high-performance LDO power management chip.Therefore, to study this subject is of particular practical significance.This thesis presents the design and implementation of an on-chip low dropout linear regulator,which is integrated into portable devices; This design, input voltage range is2.5V-5V, output voltage of1.2V, the circuit includes a bandgap reference voltage source, error amplifiers, buffers, adjust the tube, the feedback network, over-temperature and short circuit protection circuit, and undervoltage lockout circuit;The simulation results shows that the maximum output variation is smaller than6mV at a full current change from OmA to300mA; PSRR at1kHz is66.7dB; the PSRR of this LDO is73.7dB at the frequency of1kHz。At first,this paper describes the traditional linear regulator LDO performance indicators and the basic working principle.Then to analyze the stability of the traditional LDO,compare the structure of the main module.We know that the error amplifier modules use the VCCS compensation structure and bandgap voltage reference with curvature compensation structure.Determine the various sub-modules based on a compromise between the analytical results and the performance parameters,and finalize the complete LDO regulator architectures.After each sub-module circuit simulation, adjust the corresponding parameters to get the ideal results.Finally, the overall circuit simulation, adjust the parameters to meet the design requireents,and layout verification.This circuit uses a0.35um process design and simulation, LDO linear regulators, the overall simulation results show that the performance indicators are consistent with the design requirements.The designed LDO regulator with high stability and low power consumption, can be used for power management of portable devices.