Fast amp for driving multiple T/Hs

Yikes, that sounds nasty. Assuming that the drains are the outputs to the hold caps, there will be a bunch of charge injection to the left, from the sources into the buffer amps. They tend to react somewhere between mild disapproval and going totally nuts.

Gate drive will be interesting too, especially with the e-phempt parts.

I like BUF602 for driving tough stuff fast.

Some longish xx-ohm traces might allow you to get the s/h thing over with before the amp notices. You might even drive all the gates at the same time and stagger the samples with txline lengths. Somebody made a sampling scope like that once, namely a string of samplers spaced along a transmission line.

I did the reverse once, injecting various height pulses simultaneously into taps on a transmission line, to make a fast DAC. It modulates the

192 beam lines at NIF.

That was Tom McEwan at LLNL. A semi-circular transmission line with sampling gates spread along it, and radial spokes to the sampling pulser, I believe.

CH.

This is one version of the distributed DAC.

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

Do you calibrate-out the effect of each sampler removing some energy from the incoming signal?

I think McEwan's version had more stages - I saw 256 mentioned once. That must have been interesting in terms of power division.

CH

Unfortunately, most of Tom McEwan's ideas were stolen from Larry Fullerton. Here's some notes I took of a government inquiry into McEwan's patents and the resulting cancellation of all his claims due to prior art by Fullerton.

McEwan was also very active in stealing Fullerton's work in other areas.

Here are the notes, in no particular order.

The Development & Commercialization of Micropower Impulse Radar at

Lawrence Livermore National Laboratory

A Report by the

Democratic Staff

Committee on Science

U.S. House of Representatives

April 9, 1999

The original is available at:

LLNL/UC and the MIR inventor, Thomas McEwan, were aware of Fullerton's inventions, but did not cite the inventions or other publications describing them to the Patent Office as is required by law;

TDC inventor Larry Fullerton invented and patented the same technology 7 years prior to LLNL/UC;

In the late 1980s, claims were made regarding the ability of UWB radar to detect and identify stealth aircraft. The utilization of such a wide portion of the frequency spectrum to transmit information would reportedly enable the detection of stealth aircraft skins which absorb conventional radar, and the use of impulses to transmit information would reportedly allow the delineation of the sharp edges of stealth aircraft to a much higher degree than continuous-wave radar could. These claims were describedin several press articles in Aviation Week & Space Technology [12] in 1989 and 1990.

Two presentations [14] on UWB radar were given by collaborators of Larry Fullerton at the March, 1990 LANL meeting. One presentation listed Mr. Fullerton as a co-author, and the other referred to his proprietary UWB radar equipment in the text of the paper.

Also in attendance at that meeting were Thomas E. McEwan of LLNL and 9 other LLNL employees. All known press reports [15] of the meeting highlighted Fullerton's work, mentioning that he had secured several patents on the technology and describing his inventions.

Records show that Thomas McEwan and other LLNL employees began targeted UWB radar R&D immediately upon their return from the March, 1990 LANL meeting. Internal LLNL memos obtained by Democratic Staff indicate that Thomas McEwan had read at least one of the press reports surrounding the meeting which contained a description of Fullerton's inventions. In September, 1990, Thomas McEwan and David Christie (at that time also of LLNL) submitted an internal funding proposal entitled Ultra-wideband TimeDomain Imaging Radar. According to Mr. Christie's recollections, the proposal was funded. By February, 1991, LLNL was making UWB radar proposals to prospective industrial and governmental licensees, advertising a cheap, sensitive, low power, ultra-wideband radar that could fit on a single microchip.

The first LLNL Invention Disclosure forms for MIR were filed in August, 1992. In 1993, LLNL/UC filed their first UWB radar patents on what would become known as MIR technology, listing Thomas E. McEwan as the inventor and UC as the patent owner. LLNL/UC did not cite any of Larry Fullerton's patents, publications, or articles describing TDC's inventions as prior art on their early MIR patent applications. MIR was characterized as a cheap, sensitive, low power, ultra-wideband radar technology that couldfit on a single microchip and that was ready to be licensed for use in a wide variety of applications including heartbeat monitors, power tools, and automotive collision sensors. Like Fullerton's radar inventions, MIR detects and identifies targets by relying on the reception and interpretation of very short, randomly-spaced impulses of electromagnetic energy that are reflected off the targets.

In September, 1995, after learning about the LLNL/UC patents, TDC contacted both LLNL and DOE and conveyed their beliefs that the inventions described in the MIR patents were extremely similar to Fullerton's inventions. This led to extensive correspondence between TDC (and its affiliated entity Pulson), LLNL/UC and DOE. LLNL/UC denied all of TDC's allegations, and maintained that the inventions were patentably different, and moreover, that LLNL/UC did not even begin targeted UWB radar work until 1992, 2years after the March, 1990 LANL meeting. On June 19, 1997, at the request of Dr. C. Bruce Tarter, Director of LLNL, TDC submitted extensive documentation to LLNL that summarized the dispute and suggested a potential settlement. [16] This settlement was not accepted by LLNL/UC, no counter offer was made, and TDC's invitation to resolve the dispute using alternate dispute resolution was also turned down.

1. The Patent Reexamination

In May, 1998, the U.S. Patent and Trademark Office (PTO) rejected the 4core claims on LLNL's MIR motion sensor patent, as well as 8 of the remaining16 claims on the basis of the Fullerton patents.

Here are the notes. The url is 404.

The Development & Commercialization of Micropower Impulse Radar at

Lawrence Livermore National Laboratory

A Report by the

Democratic Staff

Committee on Science

U.S. House of Representatives

April 9, 1999

The original is available at:

LLNL/UC and the MIR inventor, Thomas McEwan, were aware of Fullerton's inventions, but did not cite the inventions or other publications describing them to the Patent Office as is required by law;

TDC inventor Larry Fullerton invented and patented the same technology 7 years prior to LLNL/UC;

In the late 1980s, claims were made regarding the ability of UWB radar to detect and identify stealth aircraft. The utilization of such a wide portion of the frequency spectrum to transmit information would reportedly enable the detection of stealth aircraft skins which absorb conventional radar, and the use of impulses to transmit information would reportedly allow the delineation of the sharp edges of stealth aircraft to a much higher degree than continuous-wave radar could. These claims were describedin several press articles in Aviation Week & Space Technology [12] in 1989 and 1990.

Two presentations [14] on UWB radar were given by collaborators of Larry Fullerton at the March, 1990 LANL meeting. One presentation listed Mr. Fullerton as a co-author, and the other referred to his proprietary UWB radar equipment in the text of the paper.

Also in attendance at that meeting were Thomas E. McEwan of LLNL and 9 other LLNL employees. All known press reports [15] of the meeting highlighted Fullerton's work, mentioning that he had secured several patents on the technology and describing his inventions.

Records show that Thomas McEwan and other LLNL employees began targeted UWB radar R&D immediately upon their return from the March, 1990 LANL meeting. Internal LLNL memos obtained by Democratic Staff indicate that Thomas McEwan had read at least one of the press reports surrounding the meeting which contained a description of Fullerton's inventions. In September, 1990, Thomas McEwan and David Christie (at that time also of LLNL) submitted an internal funding proposal entitled Ultra-wideband TimeDomain Imaging Radar. According to Mr. Christie's recollections, the proposal was funded. By February, 1991, LLNL was making UWB radar proposals to prospective industrial and governmental licensees, advertising a cheap, sensitive, low power, ultra-wideband radar that could fit on a single microchip.

The first LLNL Invention Disclosure forms for MIR were filed in August, 1992. In 1993, LLNL/UC filed their first UWB radar patents on what would become known as MIR technology, listing Thomas E. McEwan as the inventor and UC as the patent owner. LLNL/UC did not cite any of Larry Fullerton's patents, publications, or articles describing TDC's inventions as prior art on their early MIR patent applications. MIR was characterized as a cheap, sensitive, low power, ultra-wideband radar technology that couldfit on a single microchip and that was ready to be licensed for use in a wide variety of applications including heartbeat monitors, power tools, and automotive collision sensors. Like Fullerton's radar inventions, MIR detects and identifies targets by relying on the reception and interpretation of very short, randomly-spaced impulses of electromagnetic energy that are reflected off the targets.

In September, 1995, after learning about the LLNL/UC patents, TDC contacted both LLNL and DOE and conveyed their beliefs that the inventions described in the MIR patents were extremely similar to Fullerton's inventions. This led to extensive correspondence between TDC (and its affiliated entity Pulson), LLNL/UC and DOE. LLNL/UC denied all of TDC's allegations, and maintained that the inventions were patentably different, and moreover, that LLNL/UC did not even begin targeted UWB radar work until 1992, 2years after the March, 1990 LANL meeting. On June 19, 1997, at the request of Dr. C. Bruce Tarter, Director of LLNL, TDC submitted extensive documentation to LLNL that summarized the dispute and suggested a potential settlement.

[16] This settlement was not accepted by LLNL/UC, no counter offer was made, and TDC's invitation to resolve the dispute using alternate dispute resolution was also turned down.

1. The Patent Reexamination

In May, 1998, the U.S. Patent and Trademark Office (PTO) rejected the 4core claims on LLNL's MIR motion sensor patent, as well as 8 of the remaining16 claims on the basis of the Fullerton patents.

That's a DAC, not an ADC. I'm squirting signals into the line.

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

• 93-----------^^

Interesting. I knew that there was a patent dispute resolved in favour of TDS/Fullerton, but had assumed that it was a case of parallel development. McEwan did some really interesting things (e.g. switching

1000V MOSFETs in 2ns, this parallel-sampling oscilloscope), but that's real scumbag behaviour.

Damn shame that TDS didn't bother to turn their inventions into useful products during the lifetime of their patents. The best way to defend your IP is to make a commercial success of it. Take the lead and run with it.

CH

On Monday, September 25, 2000, Win Hill send me a pdf file and asked that I post it on my web site. His purpose was to discredit my analysis of the McEwan High-Speed Mosfet patent, 5,332,938.

Unfortunately, Win's analysis was faulty and did not show what he intended. In the circuit that was given, there was no way to propagate a

2ns pulse into the mosfet. I sent my analysis to Win, but received no reply.

It would be interesting to post these files to the web, but unfortunately I suffered a devastating disk crash and lost all my google drive files as well as the logon info.

It should be noted that if you are religiously backing up your files to the same disk, your backups are worthless. You need to back up to a separate disk so if the first one gets wiped out like mine was, you still have working copies of your files.

Yup. With a depletion part, you just pur a resistor between gate and source--the ~HOLD pulse pulls the gate low via a good diode such as a BAT15. Enhancement parts are more difficult, but in my current sitch it's basically just a few more RCs.

Nice part--roughly an LH0063 with several times the bandwidth and better DC accuracy. About the same slew rate though.

Provided that the effects on the amp are repeatable, they can be calibrated out with no huge worries.

Fun. I've used various shorted-stub contraptions to make constant-fraction discriminator triggers for picosecond laser measurements.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

NOTED!!!!!!!!!! I got hosed the same way.

$$$pending a lot of money for disk recovery only gets one tens of thousands of File001.*, File002.*, etc with each of dozens of file types having many thousands of files.

Lots of duplicates really help increase the tediousness... And you see files that you forgot about years ago...and NOT see others that you damn know existed.

One can spend months going thru that mess and only scratch he surface.

Even the Mission Impossible team would quit due to poor real recovery results.

You can make a fast ARB from txline chunks and switches:

I'm on VirtualBox. All I need are the vdi files, which contain the entire operating operating system and related files. The file recovery software cannot open vdi files, so it cannot harm them.

I wrote my file manager. It indexes all the files on my disk and can go through 509,928 files in milliseconds. It makes finding any file easy.

• Of no help when tens of thousands of File001.*, File002.*, etc are already in (name) order.

There's a lot of bad blood between the weapons labs, especially Livermore and Los Alamos. AIUI Teller (Livermore) got Oppenheimer (Los Alamos) canned in 1954, and the two parties have been at war ever since.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

You have to wonder how much that cost the nation.

Turns out the EL5167 + SAV-581 approach with a FIN1002 and 1PS10SB82 Schottky driving the gate works very well--the aperture time is well under 100 ps. The FIN1002 has a fall time of 170 ps, and it only has to slew a volt or so to turn off the pHEMT.

Signal |\ EL5167ICZ

0--------|-\ | >-*------*-----* *----------------*--0 Sampled output *--|+/ | | S | | D | | |/ | R --t----- CCC | | R | CCC *--RRRR-* R 1k | | 402 | | 30k GND *--|--|

I sometimes drive a SAV551 gate from cmos logic levels through just a big-ish resistor. It forward biases nicely at a few uA of gate current. You might use a resistor and a small bypass cap. If it always turns off during the first half a volt of driver swing, sample time will not depend on the signal level much.

Drive it from another SAV551!

This just got announced. It uses two SAV551s for switching three time ranges. The "switch" is a trimpot with three positions and a complex encoder circuit.

R1 and R2 go to the gates.

Early in the lockdown, I was bored so designed this at home, PCB layout too. I made it all analog so it didn't need any code.

This will run from a 24 or 48 volt wart. The first step is a little sugar-cube switcher, a 7812 drop-in that tolerates up to 70 volts in.

Manufacturing is miffed at a couple of things that I did on the board layout. Tough... I'm the boss.

The Amazon 10-watt attenuators seem to be pretty good, especially at these speeds. I have some TDR/TDT pics I could post.

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

I'll probably ditch the diode and replace the 1k with 2.7 pF to try to make sure that the gate enhancement doesn't tank at large positive slew rates. Forward-biasing the gate will help a lot with that, I expect.

That would save the diode capacitance and so might avoid the need for a bypass except at insane slew rates. Still have circuit strays though.

Fun.

Sure, that would be interesting.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com