Application Of Improved Genetic Algorithm To Power And Signal Integrity Of The High-Speed Circuit

With the rapid development of integrated circuit technology and packaging technology,the requirements for high performance,miniaturization,low cost,and high reliability of high-speed hybrid circuit systems are increasing.Due to that the frequency of high-speed digital circuits is increasing and the size of packaging structures continues to decrease,the signal integrity(SI),power integrity(PI)and electromagnetic compatibility(EMC)have become more and more serious.It is important to suppress noise propagation effectively while ensuring the SI and PI performance.Moreover,due to the discontinuity and non-differentiability of circuit design and optimization,designers spend a lot of time and energy in designing and optimizing circuit structures.Therefore,it is imperative to combine intelligent design methods with electromagnetic optimization to assist circuit design.This thesis focuses on the research and analysis of using the improved genetic algorithms to automatically design and optimize the electromagnetic band gap(EBG)structure and compensation structure for suppressing noise in high-speed hybrid circuit system.The main research work and innovations are summarized as follows:(1)The basic genetic algorithm(GA)is improved to increase the convergence speed and accuracy.In this thesis,three improved methods,including elite individual protection mechanism,Hamming distance initialization and non-repetitive crossover method,are integrated into the improved GA.The improved GA has the advantages of fast convergence,high success rate,high accuracy,and high calculation stability.Then,combined the improved GA with three-dimensional electromagnetic simulation,a design scheme based on the improved GA is proposed to design the EBG structure and compensation structure.(2)The improved GA is used to automatically optimize the “L” bridge EBG structure.The improved GA is used to optimize five important parameters of the EBG structure.The simultaneous switching noise(SSN)propagation can be prohibited from 0.38 GHz to 20 GHz with a suppression level of-60 dB;At the same time,the improved GA is used to automatically design a novel etched EBG structure.The SSN transmission can be suppressed from 0.37 GHz to 20 GHz with a suppression level of-50 dB.Meanwhile,the equivalent circuit model and dispersion diagram of the proposed structure are established to interpret the electromagnetic characteristics and predict the low-frequency cut-off frequency of the designed PDN.By employing the improved GA,the PDN structure can be designed automatically with the 3D Electromagnetic solver.Under this circumstance,the engineer can reduce repetitive debugging and save the time cost.The performance of the automatically designed EBG structure is also better than manual adjustment.(3)The improved GA is used to automatically optimize a novel compensation inductance structure,which is embedded in the right-angle bended differential line to suppress the differential-to-common mode conversion noise.The improved GA is used to optimize six important parameters of the compensation inductance structure.The compensation inductance structure is embedded in the inner line to reduce the difference in inductance between the inner and outer lines without occupying additional wiring space.The right-angle bent differential line with the compensation inductance structure can suppress the differential-to-common mode conversion noise from DC to 11 GHz with a suppression level of-20 dB.In addition,the equivalent circuit model of the compensation inductance structure is extracted to analyze the circuit performance;The improved GA is also used to automatically design a novel structure which is embedded in the right-angle bended differential line to suppress the differential-to-common mode conversion noise.The differential-to-common mode conversion noise can be prohibited from DC to 15 GHz with a suppression level of-20 dB.The differential mode return loss and insertion loss have been minimized by GA,leading to overall improved signal integrity(SI).The eye height of the eye diagram is increased by using the proposed structure.The common-mode noise and the time skew between the inner line and outer line are reduced by 75% and 78% in the time-domain,respectively.All the samples are fabricated based on the single-layered or multi-layered printed circuit board(PCB)standard to validate our proposed works,the measured results agree well with the simulated ones.