Based On Particle Swarm Optimization Algorithm Solve MOS Surface Potential

Compact models play an important role in connecting the development of the manufacturing process and circuit design. Their main function is to accurately reproduce the tiny characteristics of device, this to digital, analog, mixed signal and RF IC design is critical. In deep sub-micron technology, the feature sizes keep shrinking, approaching the physical limits, MOS FET also emerged many different new physical effects which have not considered before. Also with the decrease of the size, the power supply voltage drop, having a greater influence on the moderate inversion zone, thus requirements accurately and physics to describe the moderate inversion zone. Obviously, the traditional threshold voltage model is difficult to meet the increasingly demanding circuit design requirements, this is because the threshold voltage model uses a piecewise form, namely the devices work in different area with different equation, some with no physical meaning of fitting parameters connect these equations.Based on surface potential model with the advantages of better, more fully describes the physical characteristics of the device, and compared with the threshold voltage model is more flexible become the standard of a new generation compact models, become the main stream of modeling method. Surface potential model is different from the piecewise form of the threshold voltage model, but use a set of unified equation to describe the electrical characteristics of the device, including the threshold area, linear area, saturated zone, weak inversion region and strong inversion region, each workspace is consistent continuous. The surface potential model has the advantage of less model parameters, physical characteristics, high precision, and its principle is through derive the channel of surface potential equation, and the reason is that the particles of the channel can be a very good characterization of the different physical effects, then according to the obtained from solving the surface potential can derive the other 150-400 parameters in the device model. But why the original device model is not directly select surface potential, because the surface potential model is extremely complex, in addition to the physical effect is multifarious, solving the surface potential equation is also a difficult problem.As a kind of intelligent computing, Particle Swarm Optimization algorithm (Particle Swarm Optimization, PSO) is based on the individual development and exchanges among groups to complete search optimal solution in the complex space. On the one hand, PSO realized the functions of intelligent algorithm, has good function optimization and global search, on the other hand, learned the thought of the artificial life, bird flock foraging, fish learning and group theory, eliminating the complex operation, reduces parameters, possesses the advantages of simple and easy to use, efficient and practical. According to the characteristics of the surface potential equation in the model device, considering the PSO is very suitable choice for solving. In this paper, the main research work summarized as follows:(1) Deep understanding of the surface potential model. System analysis the basic idea, classification and their respective advantages and disadvantages of modeling, studies the basic principles, the main methods and parameter definition of the surface potential model, focus on analysis of poisson equation and how derive the surface potential equation of device model by poisson equation.(2) The analysis of particle swarm optimization algorithm. Through a lot of literature reading, comprehending the basic ideas, application field and developing trend of particle swarm optimization algorithm, help to explore the application of particle swarm optimization algorithm in solving the device model surface potential.(3) Combined with particle swarm optimization algorithm, designing process solve the surface potential equation of device model. Analysis program design ideas, set up a corresponding flow chart, use the JAVA object oriented language to carry on the design, by the running results show that compared with the traditional method, this algorithm in solving surface potential of device model is effective.(4) Based on the analysis of the performance of the PSO algorithm, the improved particle swarm optimization algorithm is proposed, and on the last joined the JAVA multi-thread programming system to realize program design, obtained the good operation effect.