An Ultra-fast Load-transient Response Low Dropout Linear Regulator With Large Output Current

In recent years, the switch mode power supply has been widely used because of its high efficiency and low cost. However, due to the noise injection into the power supply and its effect on noise critical circuits of the switch mode power supply, the design of low-dropout regulator (LDO) has become an urgent request for noise-sensitive systems.This paper is supported by the research project of Institute of Electronic CAD"Theoretical research and design of key techniques for deep-submicron power management IC". An ultra load-transient response low-dropout regulator IC,XD0117, is designed,including definition of the specification, further analysis of the electrical characteristics, implementation of sub-block circuits,layout,post-simulation and the final test of the whole chip. XD0117 is a single pole system with the novel current mirror structure error amplifier, which achieves the stability in full range output current with a wide bandwidth. Without the limit of slew rate current, XD0117 obtains ultra fast load-transient response and only requires a minimum 20μF capacitance .The output structure of class AB makes it possible to sink and source maximum 3A current. XD0117 provides an open-drain PGOOD signal to monitor the output regulation for the next stage application. With the multiple uses of the package pins, the testability of the chip is realized only at the cost of adding a test circuit that is very small in scale.XD0117 is based on the 0.5μm standard CMOS process. The design, layout and post-simulation has been completed using the EDA software, such as Cadence and Hspice.The IC has been taped out ,the test results show that the output voltage accuracy and load-transient response of the LDO is excellent ,the output voltage is under±2% and the load-transient response can be resumed within 8μs without overshoot and undershoot in the output current step from -2A to 2A with 5μs rising and falling time.