Power Integrity (PI/PDN) Archives

New PDN Tool to Optimize Bypass

August 2, 2025 by Rolf Østergaard

A new PDN Tool? Well, the pdntool.com page had been running for about 10 years when it suddenly stopped working. That triggered some quick efforts to get it going again. But also revealed a few things that made me take a deeper look at it, which led to a completely new version. The back story… Read more

Video: PDN Measurement with a Network Analyzer

April 2, 2020 by Rolf Østergaard

See how easily you can do a PDN measurement using a network analyzer or VNA in the video here. Building solid power distribution systems (PDN’s) is maybe the most important learning from the signal integrity training overall. Because it matters. Both for the logic functions, the signal quality (integrity) and for the radiated emissions (EMI).… Read more

How much Bypass does the Zynq have On-chip?

April 9, 2014 by Rolf Østergaard

So just how much bypass do you need for a Xilinx Zynq FPGA? Good question. It is quite obvious from looking at the chip itself that a significant amount of bypass is already implemented on the package itself. But how much is that exactly? A simple ohmmeter test shows that four of the caps are… Read more

Bypass capacitor placement is irrelevant

March 21, 2014 by Rolf Østergaard

Lots of people fuss over the exact bypass capacitor placement. Why? Lots of app notes have fluffy comments like “place as close as possible” when it comes to bypass capacitors. Why? The fact of the matter is: With fairly solid and closely coupled power and ground planes, the exact placement of bypass capacitors is not… Read more

ZedBoard Bypass Measurements

March 21, 2014 by Rolf Østergaard

There has been a lot of discussions (on this blog, on LinkedIn and on Electronics StackExchange) about the bypass scheme on the ZedBoard (a Xilinx Zynq FPGA eval board distributed by Avnet/Silica). It made sense to do some actual measurements on the board instead of relying purely on speculations. It is clear from the funny… Read more

New PDN Tool to Optimize Bypass

Video: PDN Measurement with a Network Analyzer

How much Bypass does the Zynq have On-chip?

Bypass capacitor placement is irrelevant

ZedBoard Bypass Measurements

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Rolf V. Østergaard