Breaking News
Comments
Newest First | Oldest First | Threaded View
<<   <   Page 2 / 2
MS243
User Rank
Manager
Buses and software loops
MS243   12/4/2013 8:53:48 AM
NO RATINGS
One often also has to factor in external buses and software loops -- software  loop repetition frequency can also add spurs and harmonics off of each fundamental, as do the SMPS switching spikes.

MeasurementBlues
User Rank
Blogger
Re: Very Interesting
MeasurementBlues   12/4/2013 8:25:42 AM
NO RATINGS
"coming from the days of much slower clocks and signals"

I won't comment on Max's slower days, but another issue is power supply clock frequencies, especially when high-speed digital links are involved. power supply or other clock frequencies can couple into digital clocks, creating periodic jitter. The higher the clock rate, then less jitter it takes to ruin signal integrity.\

Signal integrity engineer Daniel Chow explains periodic jitter in Jitter: Measurement References Matter. The animated graphics really bring it to life. The article has links to numerous other articles covering jitter.

MeasurementBlues
User Rank
Blogger
Re: Very Interesting
MeasurementBlues   12/4/2013 8:19:32 AM
NO RATINGS
Openings in enclosures should also be less than ¼λ for EMI purposes. openings with lengths of that size or longer are more likely to let emissions out of the box that smaller openings.

tom-ii
User Rank
Blogger
Re: Very Interesting
tom-ii   12/3/2013 7:27:45 PM
NO RATINGS
Often, for more complex systems, you can break it down some, and choose the "prime" frequencies - it will often be that much of the equipment uses similar frequencies, and you can throw these into your plan as well.  But you are correct - this can get onerous - and in those cases, you likely just have to use your best judgement and also lean on the experts that are working your grounding/shielding to tell you which frequencies will likely be the worst problems.

MS243
User Rank
Manager
Re: Very Interesting
MS243   12/3/2013 7:02:38 PM
NO RATINGS
This can be daunting on any type of vehicle, where many different systems signals can mix in a small space.   There are somespecial  techniques for managing this in one's reciever / baseband chain.

tom-ii
User Rank
Blogger
Re: Very Interesting
tom-ii   12/3/2013 3:12:37 PM
NO RATINGS
From a Motorola Semiconductor Design Guide:

 

A handy rule of thumb to determine if an interconnect trace should be considered a transmission line is if the interconnect delay is greater than 1/8th of the signal transition time, it should be considered a transmission line and afforded all of the attention required by a transmission line.

Max The Magnificent
User Rank
Blogger
Very Interesting
Max The Magnificent   12/3/2013 3:04:37 PM
NO RATINGS
I have to admit that (coming from the days of much slower clocks and signals) I'd never really thought about this -- thanks for sharing.

<<   <   Page 2 / 2


Flash Poll
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Engineer's Bookshelf
Caleb Kraft

The Martian: A Delightful Exploration of Math, Mars & Feces
Caleb Kraft
6 comments
To say that Andy Weir's The Martian is an exploration of math, Mars, and feces is a slight simplification. I doubt that the author would have any complaints, though.

The Engineering Life - Around the Web
Caleb Kraft

Surprise TOQ Teardown at EELive!
Caleb Kraft
Post a comment
This year, for EELive! I had a little surprise that I was quite eager to share. Qualcomm had given us a TOQ smart watch in order to award someone a prize. We were given complete freedom to ...

Design Contests & Competitions
Caleb Kraft

Join The Balancing Act With April's Caption Contest
Caleb Kraft
57 comments
Sometimes it can feel like you're really performing in the big tent when presenting your hardware. This month's caption contest exemplifies this wonderfully.

Engineering Investigations
Caleb Kraft

Frankenstein's Fix: The Winners Announced!
Caleb Kraft
8 comments
The Frankenstein's Fix contest for the Tektronix Scope has finally officially come to an end. We had an incredibly amusing live chat earlier today to announce the winners. However, we ...

Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)