Design Of A Synchronous Efficient DC-DC Converter Chip

With the rapid development of electronic information industry, the rate of electronicproducts innovation is increasing sharply, and the requirement for Power Management IC isbecoming much higher as the property of portable product improved. Due to the low supplyvoltages, conventional DC-DC controller chip has been unable to meet the requirements ofefficient CPU power management solutions. Therefore the synchronous rectificationtechnology is used to improve the efficiency of the power supply. The conventional currentdetection is needed to add the sensing resistor to realize current detection, but this adds theloss. Based on the investigation of DC-DC converter’s chip research status both at home andabroad, and analysis of the working principle of DC-DC in detail, a DC-DC converter chipwith high efficiency is designed in the thesis.Through the analysis of DC-DC converter’s work principle and control mode, it hasdesigned the DC-DC converter’s control loop and the whole architecture based on thesynchronous rectification technology, using synchronous rectifier instead of diode to decreasethe dissipation. It has proposed a lossless current sensing scheme by sampling the voltage ofthe metal line which connected to the high power switch tube, reflecting the current flowthrough the switch tube, no requiring additional current detection resistance. Thus the loss andchip area are reduced, the cost is declined, and the efficiency is promoted. It also focuses onthe corresponding modules circuits of the current sensing and synchronous rectification, andthe other core module circuit. Based on Cadence platform and BCD technology model,DC-DC converter chip is simulated and verified systematically by Spectre and Hspiceenvironments. Finally, the layout design of the chip is accomplished, the correctness of thechip is verified through DRC (Design Rule Check) and LVS (Layout Versus Schematics)checking.The design of efficient DC-DC converter chip’s input voltage is in the range of4.75V to18V and output voltage is in the range of0.923V to15V, output current can reach2A, andefficiency is93%. Integrated simulation results show the feasibility of technology solutions on nondestructive current detection and synchronous rectification.