Relationships between rise time, trace width, data rate, frequency

[victoryrez]

Referencing existing thread:

https://www.edaboard.com/threads/112405/

Hi, I want to use rise time to compute physical parameters like trace width/clearance etc...

Can someone explain how to compute rise time from just the data rate or fcy of operation??

E.G: For a trace running at 10 Gb/s

we assume 5 GHz...

Thus, for equal rise-time and fall time, we need time period which would be 20 ns, for a 50% duty cycle, 100 ps

Can i assume rise-time to be 10% of T
Thus, rise time = 20 ps?

 

[juan_zo]

Hello victoryrez,
For 10GHz, Time= 100pS.[/B] 50% duty cycle: 50pS rise time and, 50% 50pS fall time.
5GHz, Time= 200pS. 50% duty cycle: 100pS rise time and, 50% 100pS fall time.

Then as you say: For 5GHz, Time= 200pS. 10% duty cycle: 20pS rise time, and 90% 180pS fall time or viceversa.
You are right.

Have a nice day.

Best regards,
Juan_zo

 

[victoryrez]

Hello victoryrez,
For 10GHz, Time= 100pS.[/B] 50% duty cycle: 50pS rise time and, 50% 50pS fall time.
5GHz, Time= 200pS. 50% duty cycle: 100pS rise time and, 50% 100pS fall time.

Then as you say: For 5GHz, Time= 200pS. 10% duty cycle: 20pS rise time, and 90% 180pS fall time or viceversa.
You are right.

Have a nice day.

Best regards,
Juan_zo

Thank you Juan, that helped...