Building a virtex 7 pcb

[ultrathom]

Hi all,

I would like to build a PCB with a Virtex 7 chip which I have.

What I want is a footprint for the part, and the most basic layout for power. I thought about taking the gerber files they provide and stripping out the components I don't need. They supply gerbers for allegro. Is there a easier way ?

[Dago]

If you need to ask then you can't do it.

How would you even solder a BGA?

[JoeN]

Virtex 7s have a bunch of different pin counts (I see devices with 1157 through 1930 pins), all BGA.   You have to tell us the specific chip.  Once you have a board made, you have to be able to solder a BGA, probably one with a 1000+ pin count, which means a reflow oven.  Are you up to that?

The best way to approach this, IMHO, having done some things approaching this (but not on such a large part) is to find a schematic for a development board from any serious manufacturer.  Base your design on that.  What could go wrong at that point? For example, I enter "virtex 7 development board" into Google and soon find this:

A development board schematic based on Virtex 5:

http://www.digilentinc.com/Data/Products/GENESYS/Genesys-sch.pdf

Xilinx Virtex 7 Development Board VC707 schematics, based on the 1761 pin XC7VX485T-2FFG1761C device:

http://esimioni.web.cern.ch/esimioni/files/EvalOptoMezzanine/backup/vc707_Schematic_xtp135_rev1_0.pdf

(you may want to save this, this is password protected at Xilinx and I don't think these guys are supposed to have it available on the Intertubes.)

And after all of that, you will maybe be able to get the time-limited 30 day eval software you need to program it.  The free version will not work.  If you figure out how to get the full-feature-time-limited software to work past the 30 day limit, please tell me.  It's your duty to do so since I gave you some solid pointers here.   

[poorchava]

I'd guess minimum of 6 layers pcb, most likely 8 or more for up-to-spec operation.

Start with spartan 6 or something.

Where did you get that chip anyway? Those are several thousands of dollars apiece in retail.

[JoeN]

Code: [Select]

I'd guess minimum of 6 layers pcb, most likely 8 or more for up-to-spec operation.

Start with spartan 6 or something.

Where did you get that chip anyway? Those are several thousands of dollars apiece in retail.

I guess I shouldn't be answering this for another guy, but even very high-end FPGAs are always available used/for recovery on eBay, usually literally pennies on the dollar.  Unguaranteed, of course.  Good luck to your desoldering/reballing/resoldering efforts.   

http://www.ebay.com/sch/i.html?_nkw=virtex+recovery

I don't see any 7s right now but I have seen them before.

Good point about the 6/8 layer issue.  There are places that do cheap 4 layers now but the price goes up enormously for 6/8 layer.  It might be more economical to keep an eye out on eBay for a used development board than doing that.

[tszaboo]

Code: [Select]

I'd guess minimum of 6 layers pcb, most likely 8 or more for up-to-spec operation.

Start with spartan 6 or something.

Where did you get that chip anyway? Those are several thousands of dollars apiece in retail.

I guess I shouldn't be answering this for another guy, but even very high-end FPGAs are always available used/for recovery on eBay, usually literally pennies on the dollar.  Unguaranteed, of course.  Good luck to your desoldering/reballing/resoldering efforts.   

http://www.ebay.com/sch/i.html?_nkw=virtex+recovery

I don't see any 7s right now but I have seen them before.

Good point about the 6/8 layer issue.  There are places that do cheap 4 layers now but the price goes up enormously for 6/8 layer.  It might be more economical to keep an eye out on eBay for a used development board than doing that.

Some applications, you can omit the usage of the pins in the middle of the FPGA. Than you can route it on a 4 layer board, and the cost will not be that much anymore. That is why we always cry for QFP packages at the FPGA companies, no response of course.

[JoeN]

Code: [Select]

I'd guess minimum of 6 layers pcb, most likely 8 or more for up-to-spec operation.

Start with spartan 6 or something.

Where did you get that chip anyway? Those are several thousands of dollars apiece in retail.

I guess I shouldn't be answering this for another guy, but even very high-end FPGAs are always available used/for recovery on eBay, usually literally pennies on the dollar.  Unguaranteed, of course.  Good luck to your desoldering/reballing/resoldering efforts.   

http://www.ebay.com/sch/i.html?_nkw=virtex+recovery

I don't see any 7s right now but I have seen them before.

Good point about the 6/8 layer issue.  There are places that do cheap 4 layers now but the price goes up enormously for 6/8 layer.  It might be more economical to keep an eye out on eBay for a used development board than doing that.

Some applications, you can omit the usage of the pins in the middle of the FPGA. Than you can route it on a 4 layer board, and the cost will not be that much anymore. That is why we always cry for QFP packages at the FPGA companies, no response of course.

I wonder why there hasn't been more adoption of the dual-row VTLA packages.  They have pretty decent pin density and can be routed out very easily.  Microchip uses this package for at least one of their devices.

VTLA-124:

[scientist]

OP, can you respond? Or are you too busy trying to PTH solder the BGA?