Godson-2 General-purpose Processor-based High-speed Circuit Board Signal Integrity Simulation

The incessant developments in the manufacturing and processing technology of Integrated Circuits(IC) and Printed Circuit Board (PCB) industry have attracted our great attention by bringing out innumerous electronic devices with more and more various and powerful functions. However, day by day, the accompanying problem of Signal Integrity (SI) in circuits is also becoming one that cannot be easily overlooked by designers. The phenomena of distortion, delay, attenuation etc. in electric signals, caused by signal integrity problem, have become a bottleneck that will determine the performance and functionality of the target electronic system. Subsequently, it is obvious for the engineers that they will have to account for the problem of signal integrity in every possible period, i.e., the planning, designing and debugging of the product. In this paper the way to find out and solve the problem using simulation method during the design period is studied and then applied on a motherboard of the Godson-2 general purpose processor.After a brief description of the signal integrity problems in high speed circuit system, the signal integrity simulation environment for the motherboard of the Godson-2 processor was firstly set up: (1) The IBIS model file was created for this processor. With this model, a preliminary analysis for the I/O Buffers can be done, and more detailed and accurate signal integrity simulations become possible. (2) The ways of making signal integrity simulation on a multi-board system using either design files or EBD model files were introduced. This makes the simulation on the target system feasible and more accurate with CPU card and memory cards on it.The simulation and analysis work was then done on the motherboard system based on the Godson-2 CPU. Through a thorough simulation, many potential problems that may degrade performance or cause functional disorder were dug out. To solve the problems, some advice was given and some fixing up work was done. A second simulation was then made to guarantee that no negative effects have been introduced while the fixing-up really works.