Research And Design Of High Frequency Buck DC-DC Converter For Portable Devices

In portable devices, DC-DC converter must have high efficiency, small size, light weight and low output voltage in order to prolong battery lifetime and reduce the ripple of the output voltage.Taking the project"Theoretical Research on the Key Technique and the Design for Deep-submicron Power Management IC"as the background, this paper has described the design of the XD1132, based on the principles of Buck DC-DC converter and the theory related. This monolithic device applied to portable electronics is a synchronous Buck DC-DC converter with high efficiency and high frequency.The XD1132, using a self-oscillating control loop with zero hysteresis instead of the traditional feedback loop, has a better stability, a fast load transient response, a fast line transient response and a low complexity to design. This converter operates at 6MHz, which allows the use of tiny external devices. In the situations requiring high efficiency, this converter operates in the self-oscillating control method with zero hysteresis at heavy or middle load currents and while it has light load currents, this converter can switch to the pulse frequency modulation automatically. Otherwise in the situations requiring low noise, this converter can operate in the self-oscillating control method with zero hysteresis which makes switching frequency constant and makes switching noise easy to filter.The design and simulation of XD1132 were completed by using Cadence software based on the 0.6μm BiCMOS process. The simulation results show that both the function and performance of the chip can meet the design requirements.