-
- News
- Books
Featured Books
- design007 Magazine
Latest Issues
Current IssueAdvanced Packaging and Stackup Design
This month, our expert contributors discuss the impact of advanced packaging on stackup design—from SI and DFM challenges through the variety of material tradeoffs that designers must contend with in HDI and UHDI.
Rules of Thumb
This month, we delve into rules of thumb—which ones work, which ones should be avoided. Rules of thumb are everywhere, but there may be hundreds of rules of thumb for PCB design. How do we separate the wheat from the chaff, so to speak?
Partial HDI
Our expert contributors provide a complete, detailed view of partial HDI this month. Most experienced PCB designers can start using this approach right away, but you need to know these tips, tricks and techniques first.
- Articles
- Columns
Search Console
- Links
- Media kit
||| MENU - design007 Magazine
Estimated reading time: 1 minute
Quiet Power: Don't Forget to Terminate Cables
We know that in high-speed signal integrity measurements, one of the first rules is to properly terminate traces and cables. However, many of our PDN measurements may be limited to lower frequencies, such as measuring the switching ripple of a DC-DC converter. Do we really need to terminate our measurement cables if the signal we want to measure is the switching ripple of a converter running at 1 MHz? We may think that termination is not needed or does not matter in this case, but we may be in for some surprises!
Let us look at the output ripple of the LTM4604 converter, which was our device under test in an earlier column. The converter is powered from a 4.5V battery pack, and its output voltage is set to 1.2V. An approximate 1A DC load is created by a small incandescent bulb. The output ripple is measured by a Tektronix TDS540B oscilloscope that I recently bought on eBay. The 1 GS/s maximum real-time sampling rate and 500 MHz analog bandwidth, together with a maximum 1 mV/div vertical sensitivity makes this category of oscilloscopes very useful for many PDN measurements even today. Read the full column here.Editor's Note: This column originally appeared in the August 2013 issue of The PCB Design Magazine.
More Columns from Quiet Power
Quiet Power: An Evolution in PCB Design CostsQuiet Power: The Effect on SI and PI Board Performance
Quiet Power: 3D Effects in Power Distribution Networks
Quiet Power: Noise Mitigation in Power Planes
Quiet Power: Uncompensated DC Drop in Power Distribution Networks
Quiet Power: Ask the Experts—PDN Filters
Quiet Power: Friends and Enemies in Power Distribution
Quiet Power: Be Aware of Default Values in Circuit Simulators