Noise Peaks From Linear Voltage Regulators

Erroll Dietz is a remarkable fellow.  He started out at National Semiconductor as Bob Pease's
technician, and rose to become Chief Technology Officer.

Feedback amplifiers generally have an output impedance that rises linearly with frequency---in other words, it's
inductive.  As Dietz's short paper from Electronic Design shows, this effective inductance can
resonate with the output bypass capacitor to cause really nasty noise peaks in the 1-100 kHz region.  If you have an inexplicable noise peak in that range, a small resistor (a few tenths of an ohm to an ohm or two) in series with the regulator output can be just the ticket.

Random resources from my SED posts

Sometimes it's useful to add supporting documents, schematics, scope photos, simulations or other things to Usenet posts.  By popular request I've added links to some of these, in no particular order.

A trick for turning the usual proportional/integral (PI) loop filter of a phaselocked loop (PLL) into a   sweep generator for lock acquisition.

A big slide deck with ideas on Getting Photodetection Right (from a talk given at BBN in Cambridge MA)

A presentation from Texas Instruments showing detailed measurements of the switching noise of their OPA2188 chopper amp.

A paper from LIGO on components with low flicker noise

How To Read SED: Archive Sites and Newsfeeds

One of the nice things about is that it's widely redistributed by archive sites, some of which you can also use for posting, which is good since they made such a hash of the new Google Groups one.

Some examples:

Electronics Point

Electron Depot

It's really better to use a proper newsreader such as Thunderbird or Forte Agent.  You can get a free Usenet account from Eternal September.

Expert Case: Waymo LLC v. Uber Technologies, Inc., et al.

This was a patent and trade secret case concerning lidar (laser radar) technology for self-driving cars and trucks.  It was the biggest case I've worked on, with potential damages over $2 billion, and also one of the most fun.  I was the defendant's expert on the patent side, and we beat Google--they dropped all their patent assertions.  (This was made a lot easier by the fact that Uber wasn't infringing, of course.) 

Waymo is a former business unit of Google, and now a sister company.  They were alleging that Anthony Levandowski, former head of their self-driving car effort (Google's Project Chauffeur) stole over 14,000 files containing their trade secrets when he founded his own companies Ottomotto and Otto Trucking, and brought them with him when he sold Ottomotto to Uber.  That's the part that has had the tech world chewing popcorn and watching for the last year or so. 

The trade secret side of the case settled dramatically at the end of the first week of the February 2018 trial, during the cross-examination of Waymo's technical lead.  The settlement was for 0.34% of Uber's stock, currently valued at about $250M, which is about 10% of the damages being sought.  No cash changed hands.  No wrongdoing was admitted, and to my eye, there wasn't any; but that 10% lets everybody get back to work and avoids the jury possibly doing something random.

I did a bit of work on the trade secret side, primarily in looking for prior art to show that at least some of the alleged secrets were well known in the art, but my main contribution was on the patent side, where I was able to demonstrate by simulation, detailed examination, and operational testing that the accused Uber system (code named Fuji) did not infringe the asserted claims.  (I even got to make videos showing me blowing up several of Uber's laser drivers on purpose, to show that they didn't operate the way Waymo said they did.)  By way of deposition and expert reports, I was able to refute the plaintiff's expert, who vigorously contended otherwise but had no adequate body of evidence.  Waymo apparently recognized that they were going to lose the patent side at trial, and so dropped all their patent contentions in mid-September 2017.  It's great when the legal process gets the right answer.

Dates: July-September 2017

New Web Site

Thanks to the efforts of our newest member, Simon Hobbs, we have a new web site with a new look and lots of new content, with more to come.  We hope you enjoy it!