Phil : SAV-551 model...

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Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.





--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.
Click to expand...

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).
Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.
Click to expand...

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.

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
 
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.

Cheers

Phil Hobbs
Click to expand...

That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Two source leads do make a half-Kelvin connection.







--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.

Cheers

Phil Hobbs

That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Two source leads do make a half-Kelvin connection.
Click to expand...

The circuit I was working on had one of those flip-chip GaN FETs, an
0402 cap of a few nanofarads, and one of the triple-stacked Osram pulsed
lasers. It produced 5-ns pulses of a few amps from a 40V supply. That
was about a factor of 2 faster than competing units.

BTW: Anybody interested in a brand new, top-of-the-line Velodyne lidar
for fairly cheap? I\'ve had this one kicking around for a year, and I\'m
getting sick of tripping over the crate. So far I can\'t get the client
to take it back.

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
 
On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.
Click to expand...

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)

Two source leads do make a half-Kelvin connection.
Click to expand...

Near DC, at least. ;)

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
 
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs
Click to expand...

Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?
Click to expand...

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

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
 
On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs
Click to expand...

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On Sun, 25 Oct 2020 08:25:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.
Click to expand...

This looks new:

https://www.minicircuits.com/WebStore/dashboard.html?model=TAV2-14LN%2B

It\'s electrically similar to one of the SAV parts (low voltage, low
current) but in a better package. The data sheet is much worse... no
DC curves at all.

They label the gate RF IN and the drain RF OUT so\'s not to confuse the
poor RF boys.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 10/25/2020 10:34 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 25 Oct 2020 08:25:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.

This looks new:

https://www.minicircuits.com/WebStore/dashboard.html?model=TAV2-14LN%2B

It\'s electrically similar to one of the SAV parts (low voltage, low
current) but in a better package. The data sheet is much worse... no
DC curves at all.

They label the gate RF IN and the drain RF OUT so\'s not to confuse the
poor RF boys.
Click to expand...

Jeez. The package is no bigger than fly poop.
 
On Sun, 25 Oct 2020 11:36:28 -0500, John S <Sophi.2@invalid.org>
wrote:

On 10/25/2020 10:34 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 25 Oct 2020 08:25:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.

This looks new:

https://www.minicircuits.com/WebStore/dashboard.html?model=TAV2-14LN%2B

It\'s electrically similar to one of the SAV parts (low voltage, low
current) but in a better package. The data sheet is much worse... no
DC curves at all.

They label the gate RF IN and the drain RF OUT so\'s not to confuse the
poor RF boys.


Jeez. The package is no bigger than fly poop.
Click to expand...

That\'s a big problem with fast stuff. It needs to be tiny and needs a
lot of power dissipation, so the thermal situation can be grim.

The EPC GaN fets are really tiny BGAs, even worse. It takes real
soldering skills to use these parts, and creates powerful reasons to
avoid blowing them up.

The only way to test a circuit with parts like this is to make a
multilayer PC board, and have it assembled by experts. Keeps the
riffraff away, I guess.

It doesn\'t help that the data sheets are so bad, and that there are
very rarely Spice models for RF discretes and MMICs.

Grrrrr.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 10/25/20 11:34 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 25 Oct 2020 08:25:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.

This looks new:

https://www.minicircuits.com/WebStore/dashboard.html?model=TAV2-14LN%2B

It\'s electrically similar to one of the SAV parts (low voltage, low
current) but in a better package. The data sheet is much worse... no
DC curves at all.

They label the gate RF IN and the drain RF OUT so\'s not to confuse the
poor RF boys.
Click to expand...

Well, \'drain\' does sound like a gazinta, after all. ;)

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
 
jlarkin@highlandsniptechnology.com wrote:
,,,>
The EPC GaN fets are really tiny BGAs, even worse. It takes real
soldering skills to use these parts, and creates powerful reasons to
avoid blowing them up.

The only way to test a circuit with parts like this is to make a
multilayer PC board, and have it assembled by experts. Keeps the
riffraff away, I guess.
Click to expand...

Put some \"Loethonig\" (solved flux) on the pads, put the EPC on the
pre-soldered pads, best preheat the PCB and than take the hot air gun with low
flow. Watch under the scope,. Been there, done that...
--
Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
 
On Sun, 25 Oct 2020 10:44:10 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:36:28 -0500, John S <Sophi.2@invalid.org
wrote:

On 10/25/2020 10:34 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 25 Oct 2020 08:25:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.

This looks new:

https://www.minicircuits.com/WebStore/dashboard.html?model=TAV2-14LN%2B

It\'s electrically similar to one of the SAV parts (low voltage, low
current) but in a better package. The data sheet is much worse... no
DC curves at all.

They label the gate RF IN and the drain RF OUT so\'s not to confuse the
poor RF boys.


Jeez. The package is no bigger than fly poop.

That\'s a big problem with fast stuff. It needs to be tiny and needs a
lot of power dissipation, so the thermal situation can be grim.

The EPC GaN fets are really tiny BGAs, even worse. It takes real
soldering skills to use these parts, and creates powerful reasons to
avoid blowing them up.

The only way to test a circuit with parts like this is to make a
multilayer PC board, and have it assembled by experts. Keeps the
riffraff away, I guess.

It doesn\'t help that the data sheets are so bad, and that there are
very rarely Spice models for RF discretes and MMICs.

Grrrrr.
Click to expand...
The Chinese or someone should make a PCB with those tiny chips.
 
On Mon, 26 Oct 2020 18:17:12 +0200, LM <sala.nimi@mail.com> wrote:

On Sun, 25 Oct 2020 10:44:10 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:36:28 -0500, John S <Sophi.2@invalid.org
wrote:

On 10/25/2020 10:34 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 25 Oct 2020 08:25:34 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 25 Oct 2020 11:15:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 11:59 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 21:18:10 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 6:26 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 24 Oct 2020 17:47:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 10/24/20 2:53 PM, jlarkin@highlandsniptechnology.com wrote:
Hey, Phil,

I just nabbed your SAV-551 model

https://electrooptical.net/News/low-frequency-noise-in-ingaas-heterojunction-fets/

and noticed that there is no Cds, which I can add, and no lead
inductances, which I can add and you don\'t need for a low-frequency
model. Does Spice even allow lead inductance in a mesfet model?

I measured Cds as about 1 pF at zero drain volts, dropping below 0.5
pF above 1 volt. I guess Spice can manage the nonlinearity with some
mumble mumble parameters.

Thanks for the model. I\'ll tweak it a bit for my switching
applications.

It\'s probably a bit optimistic on the drain impedance. The Avago
ATF38143 model I started from had a bunch of parameters that LTspice
doesn\'t understand. I didn\'t either, so I just commented them out. ;)

Besides that, my main contribution was getting the noise a bit closer to
right (they were pessimstic by like 14 orders of magnitude iirc).

Any guesses about lead inductances? Maybe 1 nH pin+wire bond? Maybe
the chip sits on the source lead frame, so source inductance may be
less. It has two pins anyhow.

I need an x-ray machine with wirebond resolution.

Avago and Infineon datasheets often have a really detailed subcircuit
models. 1 nH seems on the high side. I\'ve seen laser driver circuits
that were less than half of that--about 200 pH in the drain circuit and
200 in the source. (This was based on SPICE fitting to measured pulse
shapes.) So a SWAG would be 150 pH per lead.


That\'s encouraging. Some things that I\'d like to do are wrecked in
simulation by 1 nH of drain inductance, or 0.5 assuming two source
leads. If the source pins are part of the lead frame, that could be
pretty low. I guess I could measure between the two source pins, with
TDR or something.

Or an RF generator and a scope, maybe resonate it with a cap or two.

Hard to get the cap small enough that its inductance is negligible. (It
would be a fun demo to make a loop out of high-K ceramic disc caps, so
that most of the current path is pure displacement current, and show
that it has inductance anyway.)

You folks don\'t do a lot of sine wave stuff, but that\'s the sort of
measurement that network analyzers are good at, especially handled by
somebody who knows how to de-embed the device from the fixture. (I\'m not
one of those people either--the last time I used a network analyzer for
anything nontrivial was in about 1982.)


Two source leads do make a half-Kelvin connection.

Near DC, at least. ;)

Cheers

Phil Hobbs


Suppose I bias up the gate, force some sinewave current into the
drain, ground one source, and scope the other?

Might work fine. I don\'t have a good feel for the coefficient of
inductive coupling between the two paths, but it\'s probably fairly
small--good enough for one significant figure maybe.

Cheers

Phil Hobbs

We both miss the Avago SOT-89 phemts. The source was a (relatively)
giant metal tab that could be soldered to a big ground pour with lots
of vias going down. They made great laser drivers. The SAV parts are
fine for low-level amplifying and switching, but the package is a
thermal and electrical limit.

The thing that most resembles the big Avago parts is a SOT-89 MMIC.
They are even worse characterized than the phemts.

I need to learn more about MMICS. I think there are some GaN parts
now, which might be really interesting.

This looks new:

https://www.minicircuits.com/WebStore/dashboard.html?model=TAV2-14LN%2B

It\'s electrically similar to one of the SAV parts (low voltage, low
current) but in a better package. The data sheet is much worse... no
DC curves at all.

They label the gate RF IN and the drain RF OUT so\'s not to confuse the
poor RF boys.


Jeez. The package is no bigger than fly poop.

That\'s a big problem with fast stuff. It needs to be tiny and needs a
lot of power dissipation, so the thermal situation can be grim.

The EPC GaN fets are really tiny BGAs, even worse. It takes real
soldering skills to use these parts, and creates powerful reasons to
avoid blowing them up.

The only way to test a circuit with parts like this is to make a
multilayer PC board, and have it assembled by experts. Keeps the
riffraff away, I guess.

It doesn\'t help that the data sheets are so bad, and that there are
very rarely Spice models for RF discretes and MMICs.

Grrrrr.
The Chinese or someone should make a PCB with those tiny chips.
Click to expand...

It\'s crazy that EPC doesn\'t have loaded breakout boards. We had to
make our own.

https://www.dropbox.com/s/ya13owgb7nioe5e/Z426_EPC_Tiles.jpg?dl=0



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
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