Design And Analysis Of Power Integrity Based On High Speed ​​PCB Of Mobile Computing Equipment

With the development of the design technology and manufacture process of IC,and people for the urgent demand of high-performance electronic devices,circuit system design is moving towards high-speed,high-current,low-voltage,low-power consumption.Especially in the mobile computing deivces,user demand for faster,lighter,thinner,smaller products bring us greater challenges in system power supply design.The design margin is constantly reduced and the design environment is continually worse,making the power distribution network of high-speed system design is facing a lot of difficulties.Power integrity(Power Integrity,PI) is that the system regulated power supply after the power transmission system in the degree of compliance of the specified device ports relative operating power requirements of the device. Power distribution network is the basis for the design of high-speed digital circuit system,a direct impact on the signal integrity (Signal Integrity,SI) of the system and electro magnetic intenence(Electro Magnetic Intenence,EMI) and other issues.Power distribution network(Power Delivery Network,PDN) includes a voltage regulator module(Voltage Regulator Module,VRM), PCB power ground plane,board level decoupling capacitors,package distribution network and on-chip capacitors. The power distribution network design and power integrity analysis is technology of the most complex and the most immature, the views of most non-uniform on system of high-speed circuit. With the continuous improvement of the power system design requirements, traditionally relying on the engineer experience to design circuit is not enough, the classic definition of the target impedance in the high-frequency part is no longer realistic.Power system design faces many problems in the field of engineering application.This paper, on the design basis of the traditional target impedance, combined with practical engineering problems and traditional design experience,using DC+AC design ideas, in use of simulation software, with the CPU power for example, gives a design flow of high-speed PCB power of mobile computing devices. Extract the power supply voltage and current indicators, broken down into target impedance for DC and AC, power supply PCB design, simulation of the actual design, and using an iterative method that according to each of the simulation results continue to modify the PCB until approaching as well as to meet the target impedance. In the end, simulation result is tested that it meets the requirement of product design. According with the design requirement of the target impedance, the DC impedance of the CPU power is less than2mΩ, AC impedance in the frequency band below25MHz is less than16mΩ, and simulation result meet design requirement.Lastly test result shows that the error of the test result and simulation result is less than3.5%for DC impedance,and the error of the test result and simulation result is less than3mQ for AC impedance,6mV design margin is left in the real-time voltage ripple test.The design meet product performance requirement completely.This flow can guarantee the actual performance requirement of the board-level power well, at the same time reduce the system cost and design complexity, result in a better economic efficiency. It is also a strong engineering guide and reference for other electronic products design.