[IBIS-Users] how we decide R_fixture of buffer

Hello Friends,

   I am working on one of my IO design. When I put a transmission line 
with Z0=70ohm and length is 2inch with 5pf load my rise and fall time is 
just 50nsec. When I use R_fixture =70ohm in my design then transition 
time increase to 300nsec. This cause a lot of spice and IBIS mismatch in 
my final models.
  Could you please give me an idea that how we can select a good 
R_fixture value. If you have any doc that help me to understand how we 
can select R_fixture and it's effect in final simulation.
  Customer spec say that this cell is work fine till 10pf load. I don't 
have any R_fixture and V_fixture information from customer.

Regards
Akhilesh


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