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IN hyperlynx tool,wat do u mean by SLOW,FAST and TYPICAL?

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sudhagar124

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HI,

In hyperlynx tool for SI and PI,we have three modes of simulation-FAST,TYPICAL and SLOW.Can any one explain what are these three modes of simulation.:!:
The load is of higher value in fast mode,this is my understanding. Want to make myself clear,.:shock::???:
Kindly any significant material on SI analysis.

Thanks in advance,

Sudhagar:-D
 

It is driver's slew rate. how fast a simulation can be done, these modes define. I'm not using hyperlynx , but allegro has same modes for SI simulation.

The modes depends upon the buffer(@IO Pins) behaviour, Die Capacitance and Ramp Rates.
The ramp rate values (the dV/dT values or slew rates) are required to be 20%/80% values. This implies that the rise time and the fall time are defined as the time it takes the output buffer to go from 20% of its final value to 80% of its final value.

These Modes are nothing but Slew rates. Defined in IBIS model( normally an IBIS model contain all 3 modes). It is engineers choise for simulation. Generally Typical mode is convinient to foloow.
 
mishrashashi said:
It is driver's slew rate. how fast a simulation can be done, these modes define. I'm not using hyperlynx , but allegro has same modes for SI simulation.

The modes depends upon the buffer(@IO Pins) behaviour, Die Capacitance and Ramp Rates.
The ramp rate values (the dV/dT values or slew rates) are required to be 20%/80% values. This implies that the rise time and the fall time are defined as the time it takes the output buffer to go from 20% of its final value to 80% of its final value.

These Modes are nothing but Slew rates. Defined in IBIS model( normally an IBIS model contain all 3 modes). It is engineers choise for simulation. Generally Typical mode is convinient to foloow.
Click to expand...

Thanks Shashi,
Correct me if am wrong anywhere.

So what am understanding from your statement is that,dv/dt is varied in the three modes i.e. the model is simulated in FAST mode-rise/fall time will be less than the typical and in slow mode rise/fall time will be greater than the typical and i notice that in simulation also. But how does the voltage peaks differ in fast and slow.
In fast i see higher peaks both in over and undershoot,similarly i see comparatively low peaks in SLOW mode. Can you make me clear on that.


Regrds,
Sudhagar
 

Hi Sudhagar,
If you can open your IBIS model in word pad or editor, try to find word "RAMP". In this section you can find dv/dt values in Typical , Min(Slow), Max(Fast) modes.
Below this section parasitic charecters will define and next to that Voltage level for 3 modes. These parameters are defined by IC manufaturers. IBIS models follows few specifications, for more details you can check this link
**broken link removed**

Hope This is helpful
 
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