February 24, 2018
— updated January 20, 2022
For RF folks, one of the perennial quests is for better frequency mixers: lower distortion,
lower power, better spurious performance. FETs can help. Nowadays CMOS muxes are the devices of choice for HF mixers, but to get the best performance, you still have to know how they work. Ed Oxner was a long-time Siliconix apps guy, and his paper on High dynamic range FET RF mixers is still right up there with the best.
(From a Siliconix databook, 1985.) The FET mux approach is often credited to Dan Tayloe, but since they work just the same, the “Tayloe mixer” should really be called the “Oxner mixer”.
Read more…February 24, 2018
— updated January 20, 2022
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. You can also put it in series with the cap, but if you do that, make sure it’s a pulse-withstanding type, or it’s liable to blow up by an output short-circuit, or even the inrush transient, e.g. if somebody runs your gizmo off batteries.
Read more…February 24, 2018
— updated January 18, 2020
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)
Read more…February 24, 2018
— updated June 20, 2024
One of the nice things about sci.electronics.design is that it’s widely redistributed by archive sites, some of which you can also use for posting, which is good since Google Groups no longer links to Usenet.
Some examples:
electronics-related
Narkive
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, and cheap ones from Supernews or astraweb.
SED has been around for a long time. Archives going back to 1993 are available from Archive.org, and have a lot, a lot of good stuff. (Plus the usual allotment of Usenet flame wars and so on.)
Read more…February 16, 2018
— updated January 20, 2022
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.)
Read more…