sxunxs
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mdcui said:big spacing between differential lines are also appreciated, watch the adjacent metals on the same layers as well as the on different layers, shield them if necessary.
mdcui said:big spacing between differential lines are also appreciated, watch the adjacent metals on the same layers as well as the on different layers, shield them if necessary.
srieda said:mdcui said:big spacing between differential lines are also appreciated, watch the adjacent metals on the same layers as well as the on different layers, shield them if necessary.
Differential lines MUST be laid out as close as possible... (So that noise affects them in the same way...)
The paths must be very symmetrical and as close as possible... right from the pads to the amplifier inputs. (So that there is no phase difference introduced between the differential signals)
Avoid long routing if possible (obviously signal strength.)
I am a designer and I always insist on lines to be close to each other as possible for the layout guys.. Please correct me if my understanding is wrong!!
sxunxs said:thanks.. you are right.. but when the 2 diff lines are close to each other, parasitic capacitance would be seen bet the lines.. do u know any technique to avoid this parasitic except to put a dummy path/line between them? if a had to use different metals in routing the diff lines, diff noise would be injected to them. correct me if im wrong.
srieda said:sxunxs said:thanks.. you are right.. but when the 2 diff lines are close to each other, parasitic capacitance would be seen bet the lines.. do u know any technique to avoid this parasitic except to put a dummy path/line between them? if a had to use different metals in routing the diff lines, diff noise would be injected to them. correct me if im wrong.
interesting point... but I dont think that'll matter much in terms of loading... you are right in that you should not use different metals for routing diff lines...
In fact I have another way of interpreting this.. :idea: The coupling capacitances between these might help to couple the noise between the two lines which is what we want...!!! Thus from this angle, these coupling capacitances are useful!!
Comments and arguments are invited...
forkschgrad said:will that have a big effect? i guess it may not cause a big effect on the whole design as long as those paths are parallel and differential impedance is achieved.
protonixs said:does anybody have any other idea about this topic?
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