[SI-LIST] : LVDS to Differential LVPECL conversion?

John Lipsius (jlipsius@cyras.com)
Sat, 10 Jul 1999 19:22:19 -0700

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Hello All,

Presently, I've not found yet any IC that performs=20
LVDS to LVPECL conversion. Just need one pair=20
converted.=20

My current strategy is to use the following passive method:

(50 ohm system; the following applies to each=20
line in the LVDS diff. pair)

short segment with :
10pF in series then a VBB bias of 680ohm pullup to 3.3v=20
and 1Kohm pulldown to VEE(gnd).

schematically:
LVDS input----cap---bias---LVPECL diff. driver for fanout on pcb=20

Q1: Seem ok (provided all the other SI rules followed)?=20

Q2: Is use of a ferrite bead between pullup and/or pulldown=20
resistor and its plane, to filter out noise at the VBB=20
bias point, a good idea or just overkill?

Thanks,
John Lipsius
MTS
Cyras Systems, Inc.
510-623-6631

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Hello All,
 
Presently, I've not found yet any IC = that performs=20
LVDS to LVPECL conversion.  Just = need one pair=20
converted.
 
My current strategy is to use the following passive method:
 
(50 ohm system; the following applies = to each=20
line in the LVDS diff. = pair)
 
short segment with :
10pF in series then a VBB bias of = 680ohm pullup to 3.3v
and 1Kohm pulldown to VEE(gnd).
 
schematically:
LVDS input----cap---bias---LVPECL diff. = driver for=20 fanout on pcb
 
 
Q1:  Seem ok  (provided all = the other SI=20 rules followed)?
 
Q2:  Is use of a ferrite bead = between pullup=20 and/or pulldown 
       = resistor and=20 its plane, to filter out noise at the = VBB=20
       = bias=20 point,  a good idea or just = overkill?
 
 
Thanks,
John Lipsius
   = MTS
Cyras Systems,=20 Inc.
510-623-6631
 

 
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