How to make a super fast sampling head?

[Joerg]

John Larkin wrote:

On Thu, 10 Jan 2008 20:57:38 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
On a sunny day (Thu, 10 Jan 2008 20:03:29 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
lSuhj.84616$Um6.74872@newssvr12.news.prodigy.net>:

Jan Panteltje wrote:
On a sunny day (Thu, 10 Jan 2008 17:51:19 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
rWshj.7228$pA7.4769@newssvr25.news.prodigy.net>:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?
Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.
Any suggestion for diodes?
I have a stash from Microwave Associates which has become M/A COM. You
can find the really hot stuff here but you might want to sit down when
the quote comes in:

http://www.macom.com/psc/jsp/ListParts.jsp?dataFile=mixing_detector_diodes.txt
mm 80Ghz! wow.

Good stuff. But check you bank account before ordering

Skyworks SMS7621-079, 0.25 pF schottky. I have a reel of them, 23
cents each.

Neat! That's a great deal.

Jan, in Europe you can get this brand via BFI Optilas. In case you want
to look these up:
http://www.skyworksinc.com/products_display_item.asp?did=798

--
Regards, Joerg

http://www.analogconsultants.com/

 

[John Larkin]

On Thu, 10 Jan 2008 20:57:38 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
On a sunny day (Thu, 10 Jan 2008 20:03:29 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
lSuhj.84616$Um6.74872@newssvr12.news.prodigy.net>:

Jan Panteltje wrote:
On a sunny day (Thu, 10 Jan 2008 17:51:19 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
rWshj.7228$pA7.4769@newssvr25.news.prodigy.net>:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?
Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.
Any suggestion for diodes?

I have a stash from Microwave Associates which has become M/A COM. You
can find the really hot stuff here but you might want to sit down when
the quote comes in:

http://www.macom.com/psc/jsp/ListParts.jsp?dataFile=mixing_detector_diodes.txt

mm 80Ghz! wow.


Good stuff. But check you bank account before ordering

Skyworks SMS7621-079, 0.25 pF schottky. I have a reel of them, 23
cents each.

John

 

[John Larkin]

On Thu, 10 Jan 2008 21:05:06 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

John Larkin wrote:
On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.


A lot in this field is a trade secret or barely defined. And then old
Leroy goes into a nursing home and one day takes that knowledge with him
into the grave.

Same on my main turf (medical ultrasound). Lots of stuff is never
disclosed in detail other than what's required for biocomp testing. To
avoid potential risks some isn't even written down. So if someone would
knock me over the head and walk away with the whole office contents it
wouldn't do them any good.


It would be fun to do a sampling scope/TDR as a USB dongle.


Sure would be fun. But I assume the market size would be rather paltry.
Especially in view of the ever smaller number of young lads who would
know what to actually do with such gear.

If it did TDR, you could sell bundles of them to PCB houses, and to
engineers and QC people who care about trace impedances. Especially if
it were cheap and interfaced to a PC, so it could document pcb test
coupons.

I'd design the fast stuff if somebody else handles the USB part and
the PC software. I have a slick deconvolution algorithm that would run
on the pc side and really beautify the TDR response.

John

 

[John Larkin]

On Thu, 10 Jan 2008 15:37:33 -0500, Phil Hobbs
<pcdh@SpamMeSenseless.pergamos.net> wrote:

John Larkin wrote:
On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

It would be fun to do a sampling scope/TDR as a USB dongle.

John


I just got John Mulvey's book, "Sampling Oscilloscope Circuits", that
goes through the operation of the 1969-vintage Tek samplers in truly
gory detail. If you can find a copy, that would be a great place to
start.

Got it, and most of the other Tek Concept Series books. Publishing
stuff like that would be unheard of nowadays.

For instance, they used a tunnel diode for the triggered
sweep--one diode controlled both the trigger and the reset. It also
covers the importance of getting the sampling loop right--you feed back
100.0% of the previous sample to the sampling head. This helps with
linearity and (interestingly) speed variations.

I loved tunnel diodes; too bad they're gone. The fabrication process
was insane. I bet an amateur could make them.

Cheers,

Phil Hobbs

Do you have Mark Kahr's paper on the history of samplers? The
technology dates back to the 1800's.

http://www.caip.rutgers.edu/~kahrs/books/sampling.html

John

 

[Joerg]

Jan Panteltje wrote:

On a sunny day (Thu, 10 Jan 2008 12:22:19 -0800) it happened John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
k6vco3dd3f2vpofu683olc3gj6a7ll1d8o@4ax.com>:

On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.
I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

It would be fun to do a sampling scope/TDR as a USB dongle.

John

I had some idea (not had much sleep, and then barriers do not
function on my ideas) to make a small PIC scope, say one PIC,
one graphics display (found one dirt cheap), and because PIC will
not digitise faster then a few kHz perhaps, add a sampling head just for fun.
I think the main problem is in the timebase, to do it digitally, and have
it set so it actually produces a steady picture on a repetitive signal,
could be very difficult.
And there a is sample memory size issue too...
It is just an idea, I have several other wish projects, but seems fun,
and would give me some more experience with high frequencies (I top out
at about a GHz atm).
Do I see it right that you have to adjust sample frequency gradually
to get a good 'view', is this perhaps done with some PLL?

Many ways to do it. Hint: You can build delay lines where the delay can
be set in almost infinitely fine steps. And yes, from a processor if you
want to and you can also servo that so you don't have to spend hours
aligning and calibrating. 'nuff said ;-)

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

John Larkin wrote:

On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

A lot in this field is a trade secret or barely defined. And then old
Leroy goes into a nursing home and one day takes that knowledge with him
into the grave.

Same on my main turf (medical ultrasound). Lots of stuff is never
disclosed in detail other than what's required for biocomp testing. To
avoid potential risks some isn't even written down. So if someone would
knock me over the head and walk away with the whole office contents it
wouldn't do them any good.

It would be fun to do a sampling scope/TDR as a USB dongle.

Sure would be fun. But I assume the market size would be rather paltry.
Especially in view of the ever smaller number of young lads who would
know what to actually do with such gear.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

Jan Panteltje wrote:

On a sunny day (Thu, 10 Jan 2008 20:03:29 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
lSuhj.84616$Um6.74872@newssvr12.news.prodigy.net>:

Jan Panteltje wrote:
On a sunny day (Thu, 10 Jan 2008 17:51:19 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
rWshj.7228$pA7.4769@newssvr25.news.prodigy.net>:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?
Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.
Any suggestion for diodes?

I have a stash from Microwave Associates which has become M/A COM. You
can find the really hot stuff here but you might want to sit down when
the quote comes in:

http://www.macom.com/psc/jsp/ListParts.jsp?dataFile=mixing_detector_diodes.txt

mm 80Ghz! wow.

Good stuff. But check you bank account before ordering


--
Regards, Joerg

http://www.analogconsultants.com/

 

[Jan Panteltje]

On a sunny day (Thu, 10 Jan 2008 15:37:33 -0500) it happened Phil Hobbs
<pcdh@SpamMeSenseless.pergamos.net> wrote in
<4786820D.5010307@SpamMeSenseless.pergamos.net>:

John Larkin wrote:
On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

It would be fun to do a sampling scope/TDR as a USB dongle.

John


I just got John Mulvey's book, "Sampling Oscilloscope Circuits", that
goes through the operation of the 1969-vintage Tek samplers in truly
gory detail. If you can find a copy, that would be a great place to
start. For instance, they used a tunnel diode for the triggered
sweep--one diode controlled both the trigger and the reset. It also
covers the importance of getting the sampling loop right--you feed back
100.0% of the previous sample to the sampling head. This helps with
linearity and (interestingly) speed variations.

Cheers,

Phil Hobbs

Thank you Phil.

 

[Jan Panteltje]

On a sunny day (Thu, 10 Jan 2008 20:03:29 GMT) it happened Joerg
<notthisjoergsch@removethispacbell.net> wrote in
<lSuhj.84616$Um6.74872@newssvr12.news.prodigy.net>:

Jan Panteltje wrote:
On a sunny day (Thu, 10 Jan 2008 17:51:19 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
rWshj.7228$pA7.4769@newssvr25.news.prodigy.net>:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

Any suggestion for diodes?


I have a stash from Microwave Associates which has become M/A COM. You
can find the really hot stuff here but you might want to sit down when
the quote comes in:

http://www.macom.com/psc/jsp/ListParts.jsp?dataFile=mixing_detector_diodes.txt

mm 80Ghz! wow.

 

[Jan Panteltje]

On a sunny day (Thu, 10 Jan 2008 12:22:19 -0800) it happened John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
<k6vco3dd3f2vpofu683olc3gj6a7ll1d8o@4ax.com>:

On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

It would be fun to do a sampling scope/TDR as a USB dongle.

John

I had some idea (not had much sleep, and then barriers do not
function on my ideas) to make a small PIC scope, say one PIC,
one graphics display (found one dirt cheap), and because PIC will
not digitise faster then a few kHz perhaps, add a sampling head just for fun.
I think the main problem is in the timebase, to do it digitally, and have
it set so it actually produces a steady picture on a repetitive signal,
could be very difficult.
And there a is sample memory size issue too...
It is just an idea, I have several other wish projects, but seems fun,
and would give me some more experience with high frequencies (I top out
at about a GHz atm).
Do I see it right that you have to adjust sample frequency gradually
to get a good 'view', is this perhaps done with some PLL?

 

[Phil Hobbs]

John Larkin wrote:

On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

It would be fun to do a sampling scope/TDR as a USB dongle.

John


I just got John Mulvey's book, "Sampling Oscilloscope Circuits", that

goes through the operation of the 1969-vintage Tek samplers in truly
gory detail. If you can find a copy, that would be a great place to
start. For instance, they used a tunnel diode for the triggered
sweep--one diode controlled both the trigger and the reset. It also
covers the importance of getting the sampling loop right--you feed back
100.0% of the previous sample to the sampling head. This helps with
linearity and (interestingly) speed variations.

Cheers,

Phil Hobbs

 

[John Larkin]

On Thu, 10 Jan 2008 17:51:19 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

I did one with a step-recovery diode impulse generator, feeding a
2-diode sampler. Got 70 ps risetime, roughly 5 GHz, and apparently
good waveform fidelity. The parts cost is tiny, but it's labor
intensive. The timebase and trigger stuff is more work than the
sampler.

The older Tek sampling stuff, the S-series heads and their 7000-series
plugins, are dirt cheap on ebay. But not nearly as nice and
quantitative as the 11801-series stuff.

I doubt you could make a head that would work in an 11801 frame; the
interface is undefined.

It would be fun to do a sampling scope/TDR as a USB dongle.

John

 

[Joerg]

Jan Panteltje wrote:

On a sunny day (Thu, 10 Jan 2008 17:51:19 GMT) it happened Joerg
notthisjoergsch@removethispacbell.net> wrote in
rWshj.7228$pA7.4769@newssvr25.news.prodigy.net>:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

Any suggestion for diodes?

I have a stash from Microwave Associates which has become M/A COM. You
can find the really hot stuff here but you might want to sit down when
the quote comes in:

http://www.macom.com/psc/jsp/ListParts.jsp?dataFile=mixing_detector_diodes.txt

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Jan Panteltje]

On a sunny day (Thu, 10 Jan 2008 17:51:19 GMT) it happened Joerg
<notthisjoergsch@removethispacbell.net> wrote in
<rWshj.7228$pA7.4769@newssvr25.news.prodigy.net>:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

Any suggestion for diodes?

 

[Joerg]

Jan Panteltje wrote:

J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

Usually a transistor that avalanches nicely, a chunk of good coax and
blazingly fast diodes, preferable a matched quad.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Jan Panteltje]

J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?

 

[Robert]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:grndo3ht9ndsg113kqo7l43iks4mg2ul33@4ax.com...

On Thu, 10 Jan 2008 22:44:16 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Another part you might want to look at are those blazingly fast
transistors from your companies over there, Infineon and NXP. For
example the BFP620. Ok, it's a bipolar transistor but it sports a
whopping 65GHz ft and is very cheap. Just don't push it much past 2V.

I've played with the 45 GHz SiGe bipolars, and always found them to be
slow as time-domain amps or switches. And they love to oscillate in
wideband circuits.

PHEMTS on the other hand are phenomenal. Today I was testing a cheap
NEC part, NE3509M04. Gate capacitance measures under 0.8 pF, drain is
about 0.35, Rds-on is about 6 ohms at zero gate voltage, and it
switches on/off fast and clean with ecl-type gate swings. It has no
equivalent of bipolar saturation delay; pull the gate to -0.4, and it
just turns off.

The weird thing is that Rds-on has a negative TC. I've never seen a
fet do that before.

(Used my trusty old green Boonton analog c-meter. The bottom meter
range is 0 to 1 pF, and it has provision for offsetting strays, 2/4
terminal measurements, and dc bias injection.)

John

TriQuint Semiconductor has a Prototype Chip Option program where they sell
you a place on a shared Mask Set for a lot of their PHEMT & HBT processes.
You get a small amount of chips for a smaller price with the shared Mask
running at regular intervals. The details, and prices, are listed here.

http://www.triquint.com/prodserv/foundry/proto_sched_pco.cfm#sched3

There's also a larger shared Mask program, called the Prototype Development
Quickturn, PDQ, listed on another page.

I don't see their new combined HBT and PHEMT process, TQBiHEMT, listed on
the prototype schedule but it's possible the Web page hasn't caught up yet.


Robert H.

 

[John Larkin]

On Sun, 13 Jan 2008 15:43:20 -0800, "Robert" <bobh3141@earthlink.net>
wrote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:grndo3ht9ndsg113kqo7l43iks4mg2ul33@4ax.com...
On Thu, 10 Jan 2008 22:44:16 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Another part you might want to look at are those blazingly fast
transistors from your companies over there, Infineon and NXP. For
example the BFP620. Ok, it's a bipolar transistor but it sports a
whopping 65GHz ft and is very cheap. Just don't push it much past 2V.

I've played with the 45 GHz SiGe bipolars, and always found them to be
slow as time-domain amps or switches. And they love to oscillate in
wideband circuits.

PHEMTS on the other hand are phenomenal. Today I was testing a cheap
NEC part, NE3509M04. Gate capacitance measures under 0.8 pF, drain is
about 0.35, Rds-on is about 6 ohms at zero gate voltage, and it
switches on/off fast and clean with ecl-type gate swings. It has no
equivalent of bipolar saturation delay; pull the gate to -0.4, and it
just turns off.

The weird thing is that Rds-on has a negative TC. I've never seen a
fet do that before.

(Used my trusty old green Boonton analog c-meter. The bottom meter
range is 0 to 1 pF, and it has provision for offsetting strays, 2/4
terminal measurements, and dc bias injection.)

John

TriQuint Semiconductor has a Prototype Chip Option program where they sell
you a place on a shared Mask Set for a lot of their PHEMT & HBT processes.
You get a small amount of chips for a smaller price with the shared Mask
running at regular intervals. The details, and prices, are listed here.

http://www.triquint.com/prodserv/foundry/proto_sched_pco.cfm#sched3

There's also a larger shared Mask program, called the Prototype Development
Quickturn, PDQ, listed on another page.

I don't see their new combined HBT and PHEMT process, TQBiHEMT, listed on
the prototype schedule but it's possible the Web page hasn't caught up yet.


Robert H.

Cool. What we want is...


4 3
| |
+---+
|
d
+--g
| s
| |
+---+-----+----5
| |
| |
d d
1----g-----g
s s
| |
| |
+-----+
| |
| |
2 6


which looks a lot like an old GigaBit Logic depletion-load logic gate.
It works pretty well with the NEC parts, but integrated it would
really scream.

John

 

[Robert]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:biblo31vs9u64a21runiglfcjcgs5o7aaj@4ax.com...

On Sun, 13 Jan 2008 15:43:20 -0800, "Robert" <bobh3141@earthlink.net
wrote:


"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
news:grndo3ht9ndsg113kqo7l43iks4mg2ul33@4ax.com...
On Thu, 10 Jan 2008 22:44:16 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Another part you might want to look at are those blazingly fast
transistors from your companies over there, Infineon and NXP. For
example the BFP620. Ok, it's a bipolar transistor but it sports a
whopping 65GHz ft and is very cheap. Just don't push it much past 2V.

I've played with the 45 GHz SiGe bipolars, and always found them to be
slow as time-domain amps or switches. And they love to oscillate in
wideband circuits.

PHEMTS on the other hand are phenomenal. Today I was testing a cheap
NEC part, NE3509M04. Gate capacitance measures under 0.8 pF, drain is
about 0.35, Rds-on is about 6 ohms at zero gate voltage, and it
switches on/off fast and clean with ecl-type gate swings. It has no
equivalent of bipolar saturation delay; pull the gate to -0.4, and it
just turns off.

The weird thing is that Rds-on has a negative TC. I've never seen a
fet do that before.

(Used my trusty old green Boonton analog c-meter. The bottom meter
range is 0 to 1 pF, and it has provision for offsetting strays, 2/4
terminal measurements, and dc bias injection.)

John

TriQuint Semiconductor has a Prototype Chip Option program where they sell
you a place on a shared Mask Set for a lot of their PHEMT & HBT processes.
You get a small amount of chips for a smaller price with the shared Mask
running at regular intervals. The details, and prices, are listed here.

http://www.triquint.com/prodserv/foundry/proto_sched_pco.cfm#sched3

There's also a larger shared Mask program, called the Prototype
Development
Quickturn, PDQ, listed on another page.

I don't see their new combined HBT and PHEMT process, TQBiHEMT, listed on
the prototype schedule but it's possible the Web page hasn't caught up
yet.


Robert H.



Cool. What we want is...


4 3
| |
+---+
|
d
+--g
| s
| |
+---+-----+----5
| |
| |
d d
1----g-----g
s s
| |
| |
+-----+
| |
| |
2 6


which looks a lot like an old GigaBit Logic depletion-load logic gate.
It works pretty well with the NEC parts, but integrated it would
really scream.

John

It may be worthwhile to you at those prices (bottom of the page). You'd know
better than me. But unless you're talking about larger FETs the part will
probably be dominated by the bond pads. You might be able to find someone
that can bond you up some die using less than standard size bond pads to get
more on an order.

There are free tools around to lay it out. TriQuint used to supply free
layout Libraries for IC Editor's ICED layout tools (Layout, DRC, LVS). I saw
from their web site recently that they've gone to open source and have a
free download.

TriQuint would be able to tell you about what tools their Library supports.
I used to layout customer designs in ICED and for your circuit all you'd
need to do would be to streach their standard FETs to the size you'd need.

http://www.iceditors.com/


Robert H.

 

[Robert]

"Robert" <bobh3141@earthlink.net> wrote in message
news:13olr0isln87o22@corp.supernews.com...

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message news:biblo31vs9u64a21runiglfcjcgs5o7aaj@4ax.com...
On Sun, 13 Jan 2008 15:43:20 -0800, "Robert" <bobh3141@earthlink.net
wrote:


"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
news:grndo3ht9ndsg113kqo7l43iks4mg2ul33@4ax.com...
On Thu, 10 Jan 2008 22:44:16 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jan Panteltje wrote:
J Larkin was saying his super sampling head costs 750$.
I was thinking how can you make one yourself, what else is needed?


Another part you might want to look at are those blazingly fast
transistors from your companies over there, Infineon and NXP. For
example the BFP620. Ok, it's a bipolar transistor but it sports a
whopping 65GHz ft and is very cheap. Just don't push it much past 2V.

I've played with the 45 GHz SiGe bipolars, and always found them to be
slow as time-domain amps or switches. And they love to oscillate in
wideband circuits.

PHEMTS on the other hand are phenomenal. Today I was testing a cheap
NEC part, NE3509M04. Gate capacitance measures under 0.8 pF, drain is
about 0.35, Rds-on is about 6 ohms at zero gate voltage, and it
switches on/off fast and clean with ecl-type gate swings. It has no
equivalent of bipolar saturation delay; pull the gate to -0.4, and it
just turns off.

The weird thing is that Rds-on has a negative TC. I've never seen a
fet do that before.

(Used my trusty old green Boonton analog c-meter. The bottom meter
range is 0 to 1 pF, and it has provision for offsetting strays, 2/4
terminal measurements, and dc bias injection.)

John

TriQuint Semiconductor has a Prototype Chip Option program where they
sell
you a place on a shared Mask Set for a lot of their PHEMT & HBT
processes.
You get a small amount of chips for a smaller price with the shared Mask
running at regular intervals. The details, and prices, are listed here.

http://www.triquint.com/prodserv/foundry/proto_sched_pco.cfm#sched3

There's also a larger shared Mask program, called the Prototype
Development
Quickturn, PDQ, listed on another page.

I don't see their new combined HBT and PHEMT process, TQBiHEMT, listed on
the prototype schedule but it's possible the Web page hasn't caught up
yet.


Robert H.



Cool. What we want is...


4 3
| |
+---+
|
d
+--g
| s
| |
+---+-----+----5
| |
| |
d d
1----g-----g
s s
| |
| |
+-----+
| |
| |
2 6


which looks a lot like an old GigaBit Logic depletion-load logic gate.
It works pretty well with the NEC parts, but integrated it would
really scream.

John

It may be worthwhile to you at those prices (bottom of the page). You'd
know better than me. But unless you're talking about larger FETs the part
will probably be dominated by the bond pads. You might be able to find
someone that can bond you up some die using less than standard size bond
pads to get more on an order.

There are free tools around to lay it out. TriQuint used to supply free
layout Libraries for IC Editor's ICED layout tools (Layout, DRC, LVS). I
saw from their web site recently that they've gone to open source and have
a free download.

TriQuint would be able to tell you about what tools their Library
supports. I used to layout customer designs in ICED and for your circuit
all you'd need to do would be to streach their standard FETs to the size
you'd need.

http://www.iceditors.com/


Robert H.

I should mention that they used to supply all their device Models for PSpice
as well. You'd have to model the strays yourself but they had some guidance.
Or used to.

Robert H.