6, pre-wiring stage
The basic process of pre-wiring SI planning is to first define the input parameter range (drive amplitude, impedance, tracking speed) and possible topological range (minimum / maximum length, short line length, etc.), and then run each possible simulation combination, analyze the timing and SI simulation results, and finally find an acceptable range of values.
Then, the working range is interpreted as the wiring constraint for the PCB layout. This type of "cleaning" preparation can be performed using different software tools, and the routing program can automatically handle such wiring constraints. For most users, the timing information is actually more important than the SI result, and the results of the interconnection simulation can change the wiring to adjust the timing of the signal path.
In other applications, this process can be used to determine the layout of the pins or devices that are not compatible with the system timing pointers. At this point, it is possible to fully determine the need for manual wiring of the node or do not need to terminate the node. For programmable devices and ASICs, it is also possible to adjust the selection of the output driver in order to improve the SI design or to avoid the use of discrete termination devices.

7, after wiring SI simulation
In general, SI design guidance rules is difficult to ensure that the actual wiring is not completed after the SI or timing problems. Even if the design is guided by the guide, unless you can continue to automatically check the design, otherwise, simply can not ensure that the design fully comply with the guidelines, and therefore inevitably problems. After wiring the SI simulation check will allow a planned break (or change) design rule, but this is only necessary for cost considerations or strict wiring requirements.

8, after the manufacturing stage
The above measures can ensure the SI design quality of the circuit board. After the circuit board assembly is completed, it is still necessary to place the circuit board on the test platform and use the oscilloscope or TDR (time domain reflectometer) to measure the true circuit board and simulation The results are compared. These measurement data can help you improve the model and manufacturing parameters so that you can make better (less constrained) decisions in the next pre-design work.

9, the choice of model
There are many articles on model selection, and engineers who perform static timing verification may have noticed that it is still difficult to build a model, although it is possible to obtain all the data from the device data sheet. SI simulation model is just the opposite, the model is easy to build, but the model data is difficult to obtain. In essence, the only reliable source of SI model data is the IC supplier, who must cooperate with the design engineer. The IBIS model standard provides a consistent data carrier, but the IBIS model is established and its quality assurance is costly, IC suppliers still need to promote the market demand for this investment, and circuit board manufacturers may be the only demand side market.