untitled
Newbie level 2

Hi all,
I have a question about transmission line loss simulation using W-Element in HSPICE. I was doing a simulation with length sweep to evaluate the length for 2.5Gbps PCI Express trace layout. First, I extracted a short segment of different pair trace model(e.g. 500mil) using HSPICE field solver and declared a length parameter to define the trace length. Then I instantiated this trace model with different length parameter assigned. But I didn't see a obvious loss even the trace is about 30 inches long. With 30 inches long trace, at receiver, the eye(the eye diagram for differential value between D+ and D-) height is about 0.39357v , and with 20 inches length, the value is 0.40431v.
My question:
1. Is my method right for length sweep or is there any good approach to reach this purpose ?
2. Why is the transmission line loss so little with 30 inches length versus 20 inches length?
I ever read some document introduces there is about 0.25~0.35db loss per inch for microstrip line
Thanks in advance!
Gio
I have a question about transmission line loss simulation using W-Element in HSPICE. I was doing a simulation with length sweep to evaluate the length for 2.5Gbps PCI Express trace layout. First, I extracted a short segment of different pair trace model(e.g. 500mil) using HSPICE field solver and declared a length parameter to define the trace length. Then I instantiated this trace model with different length parameter assigned. But I didn't see a obvious loss even the trace is about 30 inches long. With 30 inches long trace, at receiver, the eye(the eye diagram for differential value between D+ and D-) height is about 0.39357v , and with 20 inches length, the value is 0.40431v.
My question:
1. Is my method right for length sweep or is there any good approach to reach this purpose ?
2. Why is the transmission line loss so little with 30 inches length versus 20 inches length?
I ever read some document introduces there is about 0.25~0.35db loss per inch for microstrip line
Thanks in advance!
Gio