3 ms·
"The traces are length-matched with squiggly lines[...]. The trace matching requirement is ±10 ps according to the Zynq PCB design guide, which is approximately
by _Microft 3y ago
"The traces are length-matched with squiggly lines[...]. The trace matching requirement is ±10 ps according to the Zynq PCB design guide, which is approximately ±2mm in trace length. [...] There is also some delay difference inside the FPGA package which should be considered in the length matching."
This is a shortened excerpt from the article. It can be found below the image with six colorful images of PCB layers. I'm curious how the delays inside the FPGA package are known. Is there a table which pin adds how much delay to a signal or something like that?
- henrikf 3y agoThe FPGA manufacturer has characterized all their package pin delays. It's possible to export a csv file with internal delays of the package for each pin from the FPGA design tool. With Xilinx Vivado it's just File -> Export I/O Ports.
- _Microft 3y agoDoes KiCad allow to take these delays for each pin into account automatically or do you need to do all that manually? Edit: it's using the pad property of "pad-to-die-length" if doing it manually, right?
- henrikf 3y agoNo, it needs to be done manually. It wasn't as tedious as it sounds though. Most of the pins are very close in delay already and there were just few traces that I had to adjust a little.
- mhh__ 3y agoHow is kicad getting along with RF work in 2024, would you say? I did some prototyping but never got the stage if actually fumbling around with PCBs a few years ago, things seemed to progressing quite well.
- Brusco_RF 3y agoOne of the main benefits of using an FPGA is that you can compensate for trace length mismatch with timing constraints
- rcxdude 3y agoNot usually with IO ports directly associated with hard IP blocks like the DDR controller in the Zynq though.