So I have this gig coming in to build charge amps for a French ion >accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by
5 mm, connected with a ~80 mm long, teflon insulated cable.
Fun.
SPICE says that it can be done stably, with realistic strays, using
three Mini-Circuits pHEMTs in parallel and a BFU520A NPN cascode.
I have some test boards on order, courtesy of Simon, so in a couple of
weeks we'll see if it can actually be made to work.
With things like this, the first goal is to keep them from oscillating >someplace up in the gigahertz, and the second is to ake them do what you >want.
Parallelling devices with 12-GHz fmax is a good way to make them
oscillate. The trick in this instance seems to be source degeneration
using Murata's magical BLV03VK600SNLD ferrite bead.
Unlike the vast majority of beads, they're specified by the impedance at
**5 GHz** instead of 100 MHz--these ones are 60 ohm, but you can get 220
ohm ones too (BLV03VK221SNLG).
I spent a bit of time using similar tricks to do a lab amp similar to
our LA22 product(*), but with 200 MHz bandwidth instead of 20, and 0.3 >nV/sqrt(Hz) noise instead of 1.1 nV. The spherical cows think it can do
all that with 1.8 ns edges and no overshoot. We'll see!
<https://electrooptical.net/www/sed/500xLabAmpTransient.png> ><https://electrooptical.net/www/sed/500xLabAmp0.28nVto200MHz1.8nsTr.png>
The schematic is a bit busy, as it has to have a lot of strays put in to
get anything vaguely meaningful, and I had to scrunch it a bit
(connecting blocks using flags rather than wires in some cases) to make
it fit in the window. (The actual product schematic will probably be
fairly different, but we'll see.)
I have no idea how accurate the pHEMT model is, so I need to build some
test boards and find out. Fortunately we can get them monstrous cheap
from JLCPCB these days. (**)
Cheers
Phil Hobbs
(*) More details at <https://hobbs-eo.com/products/la-22-lab-amplifier>.
(**) JLCPCB raised a bunch of Series B money in late 2022, so maybe all
those cheap boards are being subsidized by VC money. Enjoy it while it >lasts!
So I have this gig coming in to build charge amps for a French ion >accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by
5 mm, connected with a ~80 mm long, teflon insulated cable.
Fun.
SPICE says that it can be done stably, with realistic strays, using
three Mini-Circuits pHEMTs in parallel and a BFU520A NPN cascode.
I have some test boards on order, courtesy of Simon, so in a couple of
weeks we'll see if it can actually be made to work.
With things like this, the first goal is to keep them from oscillating >someplace up in the gigahertz, and the second is to ake them do what you >want.
Parallelling devices with 12-GHz fmax is a good way to make them
oscillate. The trick in this instance seems to be source degeneration
using Murata's magical BLV03VK600SNLD ferrite bead.
Unlike the vast majority of beads, they're specified by the impedance at
**5 GHz** instead of 100 MHz--these ones are 60 ohm, but you can get 220
ohm ones too (BLV03VK221SNLG).
I spent a bit of time using similar tricks to do a lab amp similar to
our LA22 product(*), but with 200 MHz bandwidth instead of 20, and 0.3 >nV/sqrt(Hz) noise instead of 1.1 nV. The spherical cows think it can do
all that with 1.8 ns edges and no overshoot. We'll see!
<https://electrooptical.net/www/sed/500xLabAmpTransient.png> ><https://electrooptical.net/www/sed/500xLabAmp0.28nVto200MHz1.8nsTr.png>
The schematic is a bit busy, as it has to have a lot of strays put in to
get anything vaguely meaningful, and I had to scrunch it a bit
(connecting blocks using flags rather than wires in some cases) to make
it fit in the window. (The actual product schematic will probably be
fairly different, but we'll see.)
I have no idea how accurate the pHEMT model is, so I need to build some
test boards and find out. Fortunately we can get them monstrous cheap
from JLCPCB these days. (**)
Cheers
Phil Hobbs
(*) More details at <https://hobbs-eo.com/products/la-22-lab-amplifier>.
(**) JLCPCB raised a bunch of Series B money in late 2022, so maybe all
those cheap boards are being subsidized by VC money. Enjoy it while it >lasts!
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion >>accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by
5 mm, connected with a ~80 mm long, teflon insulated cable.
Fun.
SPICE says that it can be done stably, with realistic strays, using
three Mini-Circuits pHEMTs in parallel and a BFU520A NPN cascode.
I have some test boards on order, courtesy of Simon, so in a couple of >>weeks we'll see if it can actually be made to work.
With things like this, the first goal is to keep them from oscillating >>someplace up in the gigahertz, and the second is to ake them do what you >>want.
Parallelling devices with 12-GHz fmax is a good way to make them
oscillate. The trick in this instance seems to be source degeneration >>using Murata's magical BLV03VK600SNLD ferrite bead.
Unlike the vast majority of beads, they're specified by the impedance at >>**5 GHz** instead of 100 MHz--these ones are 60 ohm, but you can get 220 >>ohm ones too (BLV03VK221SNLG).
I spent a bit of time using similar tricks to do a lab amp similar to
our LA22 product(*), but with 200 MHz bandwidth instead of 20, and 0.3 >>nV/sqrt(Hz) noise instead of 1.1 nV. The spherical cows think it can do >>all that with 1.8 ns edges and no overshoot. We'll see!
<https://electrooptical.net/www/sed/500xLabAmpTransient.png> >><https://electrooptical.net/www/sed/500xLabAmp0.28nVto200MHz1.8nsTr.png>
The schematic is a bit busy, as it has to have a lot of strays put in to >>get anything vaguely meaningful, and I had to scrunch it a bit
(connecting blocks using flags rather than wires in some cases) to make
it fit in the window. (The actual product schematic will probably be >>fairly different, but we'll see.)
I have no idea how accurate the pHEMT model is, so I need to build some >>test boards and find out. Fortunately we can get them monstrous cheap
from JLCPCB these days. (**)
Cheers
Phil Hobbs
(*) More details at <https://hobbs-eo.com/products/la-22-lab-amplifier>.
(**) JLCPCB raised a bunch of Series B money in late 2022, so maybe all >>those cheap boards are being subsidized by VC money. Enjoy it while it >>lasts!
I'm still using ferric chloride but it's getting harder to find these
days. There ought to be a better way using lasers to cut the traces by
now. You wouldn't need that much power, would you? I'd have thought
maybe 4 or 5 Watts would do it for your typical FR4.
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion
accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by
5 mm, connected with a ~80 mm long, teflon insulated cable.
Yikes. What's the capacitance? You might almost start with a
transformer!
I did a wire chamber amp array for CERN. That's a whole nother story.
Fun.
SPICE says that it can be done stably, with realistic strays, using
three Mini-Circuits pHEMTs in parallel and a BFU520A NPN cascode.
I have some test boards on order, courtesy of Simon, so in a couple of
weeks we'll see if it can actually be made to work.
With things like this, the first goal is to keep them from oscillating
someplace up in the gigahertz, and the second is to ake them do what you
want.
I have a 50 MHz triggered LC oscillator based on a SAV541. It likes to oscillate at all sorts of frequencies, like 6 GHz (according to our 6
GHz scope.)
Mini has some new, basically repackaged, versions, which may have less wirebond parasitics.
In my experience, the sources should be hard grounded. The magic beads
in the gate seem to help. But the layout really dominates.
Parallelling devices with 12-GHz fmax is a good way to make them
oscillate. The trick in this instance seems to be source degeneration
using Murata's magical BLV03VK600SNLD ferrite bead.
Unlike the vast majority of beads, they're specified by the impedance at
**5 GHz** instead of 100 MHz--these ones are 60 ohm, but you can get 220
ohm ones too (BLV03VK221SNLG).
I spent a bit of time using similar tricks to do a lab amp similar to
our LA22 product(*), but with 200 MHz bandwidth instead of 20, and 0.3
nV/sqrt(Hz) noise instead of 1.1 nV. The spherical cows think it can do
all that with 1.8 ns edges and no overshoot. We'll see!
<https://electrooptical.net/www/sed/500xLabAmpTransient.png>
<https://electrooptical.net/www/sed/500xLabAmp0.28nVto200MHz1.8nsTr.png>
The schematic is a bit busy, as it has to have a lot of strays put in to
get anything vaguely meaningful, and I had to scrunch it a bit
(connecting blocks using flags rather than wires in some cases) to make
it fit in the window. (The actual product schematic will probably be
fairly different, but we'll see.)
I have no idea how accurate the pHEMT model is, so I need to build some
test boards and find out. Fortunately we can get them monstrous cheap >>from JLCPCB these days. (**)
(*) More details at <https://hobbs-eo.com/products/la-22-lab-amplifier>.
(**) JLCPCB raised a bunch of Series B money in late 2022, so maybe all
those cheap boards are being subsidized by VC money. Enjoy it while it
lasts!
On 2024-02-28 18:05, john larkin wrote:
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion
accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by
5 mm, connected with a ~80 mm long, teflon insulated cable.
Yikes. What's the capacitance? You might almost start with a
transformer!
I thought about it, but it's hard to get the ferrite losses low enough
to achieve those noise levels. The noise temperature (baseband to 200
MHz) is less than 30 K.
I'm listening intently. Say on!
I did a wire chamber amp array for CERN. That's a whole nother story.
On Wed, 28 Feb 2024 18:47:15 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-02-28 18:05, john larkin wrote:
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion
accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by >>>> 5 mm, connected with a ~80 mm long, teflon insulated cable.
Yikes. What's the capacitance? You might almost start with a
transformer!
I thought about it, but it's hard to get the ferrite losses low enough
to achieve those noise levels. The noise temperature (baseband to 200
MHz) is less than 30 K.
I'm listening intently. Say on!
I did a wire chamber amp array for CERN. That's a whole nother story.
Image a bunch of planes, I think it was four, each two sheets of
aluminized mylar with a few hundred parallel wires between. The planes
are oriented at different angles. Some particle of scientific interest
blasts through the planes and ionizes some exotic gas and we want to
see of there's a coherent track and what direction it's in. I recall a
big mag field and a final scintillator. There are many millions of
events per second, all tangled, and people want enough data to get
Nobel prizes.
There's a high voltage between the sheets and the tiny wires so a
particle has a lot of avalanche gain, so we get a big, fast signal. I
used an ECL gate in linear mode as the first amps.
The real problem was the torrent of confusing data. My idea was
"progressive enrichment" to reduce the data rate to something
managible. There were two layers of brute-force ECL logic to decode if
the hits might qualify as a track. Then an FPGA, and finally the data
was logged to disk for analysis and prizes.
I did this for some people at UCLA, who rented a site at Cern, a proton-proton collision thing. I got to meet Lisa Schlein, who you
have probably heard on NPR.
https://pubs.aip.org/physicstoday/online/17771/Obituary-of-Peter-Schlein
John Larkin <jl@997PotHill.com> wrote:
On Wed, 28 Feb 2024 18:47:15 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-02-28 18:05, john larkin wrote:
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion
accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz)
noise, when hung off a detector using 250-mm diameter plates, spaced by >>>>> 5 mm, connected with a ~80 mm long, teflon insulated cable.
Yikes. What's the capacitance? You might almost start with a
transformer!
I thought about it, but it's hard to get the ferrite losses low enough
to achieve those noise levels. The noise temperature (baseband to 200
MHz) is less than 30 K.
I'm listening intently. Say on!
I did a wire chamber amp array for CERN. That's a whole nother story.
Image a bunch of planes, I think it was four, each two sheets of
aluminized mylar with a few hundred parallel wires between. The planes
are oriented at different angles. Some particle of scientific interest
blasts through the planes and ionizes some exotic gas and we want to
see of there's a coherent track and what direction it's in. I recall a
big mag field and a final scintillator. There are many millions of
events per second, all tangled, and people want enough data to get
Nobel prizes.
There's a high voltage between the sheets and the tiny wires so a
particle has a lot of avalanche gain, so we get a big, fast signal. I
used an ECL gate in linear mode as the first amps.
The real problem was the torrent of confusing data. My idea was
"progressive enrichment" to reduce the data rate to something
managible. There were two layers of brute-force ECL logic to decode if
the hits might qualify as a track. Then an FPGA, and finally the data
was logged to disk for analysis and prizes.
I did this for some people at UCLA, who rented a site at Cern, a
proton-proton collision thing. I got to meet Lisa Schlein, who you
have probably heard on NPR.
https://pubs.aip.org/physicstoday/online/17771/Obituary-of-Peter-Schlein
Interesting. How did the first two layers work?
Cheers
Phil Hobbs
On Fri, 1 Mar 2024 13:04:49 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jl@997PotHill.com> wrote:
On Wed, 28 Feb 2024 18:47:15 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-02-28 18:05, john larkin wrote:
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion >>>>>> accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz) >>>>>> noise, when hung off a detector using 250-mm diameter plates, spaced by >>>>>> 5 mm, connected with a ~80 mm long, teflon insulated cable.
Yikes. What's the capacitance? You might almost start with a
transformer!
I thought about it, but it's hard to get the ferrite losses low enough >>>> to achieve those noise levels. The noise temperature (baseband to 200 >>>> MHz) is less than 30 K.
I'm listening intently. Say on!
I did a wire chamber amp array for CERN. That's a whole nother story. >>>>>
Image a bunch of planes, I think it was four, each two sheets of
aluminized mylar with a few hundred parallel wires between. The planes
are oriented at different angles. Some particle of scientific interest
blasts through the planes and ionizes some exotic gas and we want to
see of there's a coherent track and what direction it's in. I recall a
big mag field and a final scintillator. There are many millions of
events per second, all tangled, and people want enough data to get
Nobel prizes.
There's a high voltage between the sheets and the tiny wires so a
particle has a lot of avalanche gain, so we get a big, fast signal. I
used an ECL gate in linear mode as the first amps.
The real problem was the torrent of confusing data. My idea was
"progressive enrichment" to reduce the data rate to something
managible. There were two layers of brute-force ECL logic to decode if
the hits might qualify as a track. Then an FPGA, and finally the data
was logged to disk for analysis and prizes.
I did this for some people at UCLA, who rented a site at Cern, a
proton-proton collision thing. I got to meet Lisa Schlein, who you
have probably heard on NPR.
https://pubs.aip.org/physicstoday/online/17771/Obituary-of-Peter-Schlein >>>
Interesting. How did the first two layers work?
Cheers
Phil Hobbs
Well, it's been over 30 years. I recall that the first layer was to OR
pulses in a number of patches of each of two planes, and AND all the
possible patch pairs and see if there was a candidate track. Then do
that for a second pair of planes. Then AND again to see if four
patches had a simultaneous hit that suggests a track. If so, pass all
the wire hit pulses into the FPGAs. It would have been cool to
time-stamp every hit on every wire, but there wasn't the budget for
that, and it would have been a lot of data.
Nowadays it could be most all FPGA, since they are faster now.
Some of these collider sites save a petabyte of data per day. Big
money.
John Larkin <jl@997PotHill.com> wrote:
On Fri, 1 Mar 2024 13:04:49 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jl@997PotHill.com> wrote:
On Wed, 28 Feb 2024 18:47:15 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-02-28 18:05, john larkin wrote:
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
So I have this gig coming in to build charge amps for a French ion >>>>>>> accelerator lab.
The specs are for 1 kHz - 60 MHz, ideally less than 0.3 nV/sqrt(Hz) >>>>>>> noise, when hung off a detector using 250-mm diameter plates, spaced by >>>>>>> 5 mm, connected with a ~80 mm long, teflon insulated cable.
Yikes. What's the capacitance? You might almost start with a
transformer!
I thought about it, but it's hard to get the ferrite losses low enough >>>>> to achieve those noise levels. The noise temperature (baseband to 200 >>>>> MHz) is less than 30 K.
I'm listening intently. Say on!
I did a wire chamber amp array for CERN. That's a whole nother story. >>>>>>
Image a bunch of planes, I think it was four, each two sheets of
aluminized mylar with a few hundred parallel wires between. The planes >>>> are oriented at different angles. Some particle of scientific interest >>>> blasts through the planes and ionizes some exotic gas and we want to
see of there's a coherent track and what direction it's in. I recall a >>>> big mag field and a final scintillator. There are many millions of
events per second, all tangled, and people want enough data to get
Nobel prizes.
There's a high voltage between the sheets and the tiny wires so a
particle has a lot of avalanche gain, so we get a big, fast signal. I
used an ECL gate in linear mode as the first amps.
The real problem was the torrent of confusing data. My idea was
"progressive enrichment" to reduce the data rate to something
managible. There were two layers of brute-force ECL logic to decode if >>>> the hits might qualify as a track. Then an FPGA, and finally the data
was logged to disk for analysis and prizes.
I did this for some people at UCLA, who rented a site at Cern, a
proton-proton collision thing. I got to meet Lisa Schlein, who you
have probably heard on NPR.
https://pubs.aip.org/physicstoday/online/17771/Obituary-of-Peter-Schlein >>>>
Interesting. How did the first two layers work?
Cheers
Phil Hobbs
Well, it's been over 30 years. I recall that the first layer was to OR
pulses in a number of patches of each of two planes, and AND all the
possible patch pairs and see if there was a candidate track. Then do
that for a second pair of planes. Then AND again to see if four
patches had a simultaneous hit that suggests a track. If so, pass all
the wire hit pulses into the FPGAs. It would have been cool to
time-stamp every hit on every wire, but there wasn't the budget for
that, and it would have been a lot of data.
Nowadays it could be most all FPGA, since they are faster now.
Some of these collider sites save a petabyte of data per day. Big
money.
Must have been a crap ton of ECL. (That’s ‘merde tonne’ for the SI crowd.)
Cheers
Phil Hobbs
On Fri, 1 Mar 2024 13:04:49 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote
John Larkin <jl@997PotHill.com> wrote:
On Wed, 28 Feb 2024 18:47:15 -0500, Phil Hobb <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-02-28 18:05, john larkin wrote:
On Wed, 28 Feb 2024 17:11:52 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
CERN wants to build an even bigger ring now. I don't think it's worth
it, as putting more bootprints on the moon isn't worth it.
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