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发表于 2012-10-29 23:11:29
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Noise Analysis Settings
Noise analysis settings include:
1 loading the input noise model,
The primary input for noise analysis is a cdB library, which contains characterized noise data. In the absence of a cdB file, you can use a Liberty library (.lib) file. However, it is strongly recommended that you use a cdB noise library for SI analysis.
2 configuring the timing windows,
Timing windows are used to filter out signals that are not switching simultaneously. The internal timing engine computes the timing windows and slew rates automatically. Alternatively, you can load the timing window information by using a timing window format (TWF) file.
3 choosing the noise analysis engine,
The Encounter software uses native signal integrity analysis to perform crosstalk analysis. This engine is same as the one used by Encounter Timing System. If you are using Encounter Timing System as the SI signoff tool, the same settings can be applied in Encounter for performing noise analysis by using equivalent CeltIC NDC commands.
4 setting the delta delay threshold,
You can set the delta delay threshold for noise-on-delay analysis using the following command:
setSIMode -deltaDelayThreshold value
By default, the Encounter software uses the same default delta delay threshold value that is used by the internal SI engine, which is 1ps.
5 specifying the virtual attacker mode.
To efficiently model the many small attackers on a victim net, the SI analysis engine replaces them with an imaginary net, called a virtual attacker. The two main characteristics of a virtual attacker are: coupling capacitance, and the voltage source waveform used as a transition on the virtual attacker. |
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