Package length
shinefutureee , 07-25-2017, 06:28 AM
Hello All,
I'm wondering if anyone could help me.
Recently I came across the topic package length in some articles which explains when the frquency is above
500 MHZ we should take package length into account.I decided to start designing a zinq based design with ddr3
memory however Xilinx doesn't provide package length info but Altera company does it.please take a look at image I've attached to post,this is so obvious distance from silicon die to chip's pad.my question is do we have to
take them into account?is it possible to do matching length?(lengths differences are noticeable).how can I get Xilinx info based length like Altera's one?
I'm wondering if anyone could help me.
Recently I came across the topic package length in some articles which explains when the frquency is above
500 MHZ we should take package length into account.I decided to start designing a zinq based design with ddr3
memory however Xilinx doesn't provide package length info but Altera company does it.please take a look at image I've attached to post,this is so obvious distance from silicon die to chip's pad.my question is do we have to
take them into account?is it possible to do matching length?(lengths differences are noticeable).how can I get Xilinx info based length like Altera's one?
mairomaster , 07-25-2017, 07:36 AM
I have worked we Altera Cyclone/Arria V series and I've never seen such values stated. If the design guide doesn't say anything about this, you can just rely on matching the signal length outside the package. If there is a big difference withing the package and it would be an actual problem, it will surely be clearly stated somewhere in the documentation.
Where is your screenshot from? Maybe some old series?
Where is your screenshot from? Maybe some old series?
shinefutureee , 07-25-2017, 09:09 AM
Old series?I don't think startix or max series are old.these information are provided in xlsx format (excel) based on chip's name which is so useful.
But the distance or difference gets worse when the number of pads are more for example the screen shot is referred to a 484 BGA package.totally large
BGAs are more problematic.in matching length we talk about 0.1mms but ....!!!!!
But the distance or difference gets worse when the number of pads are more for example the screen shot is referred to a 484 BGA package.totally large
BGAs are more problematic.in matching length we talk about 0.1mms but ....!!!!!
robertferanec , 07-26-2017, 10:04 AM
- yes, if chip manufacturer lists the length in package and it is clearly different for each signal, then I would include the length in package for length matching calculations.
- If they do not say the length in package, assume, that the length in package is same.
- If they do not say the length in package, assume, that the length in package is same.
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