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

[sudhagar124]

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

 

[mishrashashi]

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.

 

[sudhagar124]

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.

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

 

[mishrashashi]

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