The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
On Wed, 4 Sep 2024 17:54:19 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
There must be some property of this universe that prefers N-type
devices.
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in <6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
Thanks. It’s not a 50-ohm system, so using those would be hard. I have >thousands for personal use, but can’t put them in licensed designs, which
is what I’m moaning about.
Cheers
Phil Hobbs
On 5/09/2024 7:54 am, Phil Hobbs wrote:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno
who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
But you could use the Renesa HFA3096, which includes two 5.5GHz PNP parts.
https://www.renesas.com/us/en/document/dst/hfa3046-hfa3096-hfa3127-hfa3128-datasheet
Not cheap, but still in production.
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >>>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps >>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay. >>>
Thanks. It’s not a 50-ohm system, so using those would be hard. I have
thousands for personal use, but can’t put them in licensed designs, which >> is what I’m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise
things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
On 9/5/2024 7:15 AM, Bill Sloman wrote:
On 5/09/2024 7:54 am, Phil Hobbs wrote:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno
who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
But you could use the Renesa HFA3096, which includes two 5.5GHz PNP parts. >>
https://www.renesas.com/us/en/document/dst/hfa3046-hfa3096-hfa3127-hfa3128-datasheet
Not cheap, but still in production.
They even provide the S parameters, isn't that nice. 8 volts CEO is a
bit limiting, though.
Someone must make the NTE2403 as far as I know they're just a re-seller, yeah? Who would have thought repackaging 2N3055s and selling them for $3
a pop wasn't a growth industry..
The Renesas parts are very disappointing in actual use, on account of their huge Ree’, Rbb’, and package inductance, as I found out to my cost long ago.
Am 05.09.24 um 20:17 schrieb Phil Hobbs:
The Renesas parts are very disappointing in actual use, on account of their >> huge Ree’, Rbb’, and package inductance, as I found out to my cost long >> ago.
They helped me make a nice 20-30 ns 1:1000 time stretcher, even in these funny space-proof flatpacks with even more L.
Gerhard
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >>>>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay. >>>>
Thanks. It’s not a 50-ohm system, so using those would be hard. I have
thousands for personal use, but can’t put them in licensed designs, which >>> is what I’m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise
things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of,
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot >without adding much noise at all--way better than an NPN follower after
the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via
the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its
gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from
its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit >subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late >times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >>>>>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay. >>>>>
Thanks. ItÂ’s not a 50-ohm system, so using those would be hard. I have >>>> thousands for personal use, but canÂ’t put them in licensed designs, which
is what IÂ’m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise
things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of,
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot
without adding much noise at all--way better than an NPN follower after
the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via
the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its
gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from
its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late
times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
john larkin <jl@650pot.com> wrote:
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >>>>>>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
Thanks. It?s not a 50-ohm system, so using those would be hard. I have >>>>> thousands for personal use, but can?t put them in licensed designs, which
is what I?m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise
things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of, >>>
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot
without adding much noise at all--way better than an NPN follower after
the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via >>> the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its
gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from >>> its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late
times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
I’ve used them a fair amount in front ends, generally with a SiGe NPN >cascode-slash-drain bootstrap. Their transconductance is a few times
higher than a CPH3910’s, but not as good as the local-feedback circuit’s.
pHEMTs have very low drain impedance—the late lamented ATF38143 had a
voltage gain of ~0.7 as a follower, even with a current sink in the tail.
Their amazing noise floor (~0.3 nV in 1 Hz) makes them well worth patching >up, but they do take some patching.
Cheers
Phil Hobbs
The reason I care about getting such accurate bootstraps is a bit subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late times, which screws up measurements. 0.9997 is dramatically better.
CheersGerhard
It seems, my 1st try did not work
Am 05.09.24 um 16:49 schrieb Phil Hobbs:
The reason I care about getting such accurate bootstraps is a bit subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late times, which screws up measurements. 0.9997 is dramatically better.
I've played with Bob Widlar's FET follower replacement:
< >https://www.flickr.com/photos/137684711@N07/53830817262/in/dateposted-public/
>
Gain seems to be 1.000 and noise is quite OK.
I wonder how this would work with today's transistors such as
BFP840 & friends. And no PNPs.
I have not yet built it.
E1 makes a noisy Vcc to see how many nV/rtHz I need there,
Q4, Q5 are just parking lots. V3 prevents Spice from crashing.
---
Vceo is no problem ( slightly older post)
Nobody forces us to leave the base open.
CheersGerhard
It seems, my 1st try did not work
Am 05.09.24 um 16:49 schrieb Phil Hobbs:
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late
times, which screws up measurements. 0.9997 is dramatically better.
I've played with Bob Widlar's FET follower replacement:
< https://www.flickr.com/photos/137684711@N07/53830817262/in/dateposted-public/
>
Gain seems to be 1.000 and noise is quite OK.
I wonder how this would work with today's transistors such as
BFP840 & friends. And no PNPs.
I have not yet built it.
E1 makes a noisy Vcc to see how many nV/rtHz I need there,
Q4, Q5 are just parking lots. V3 prevents Spice from crashing.
---
Vceo is no problem ( slightly older post)
Nobody forces us to leave the base open.
CheersGerhard
On Thu, 5 Sep 2024 22:44:36 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@650pot.com> wrote:
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
Thanks. It?s not a 50-ohm system, so using those would be hard. I have >>>>>> thousands for personal use, but can?t put them in licensed designs, which
is what I?m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise >>>>> things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of, >>>>
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot >>>> without adding much noise at all--way better than an NPN follower after >>>> the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via >>>> the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its >>>> gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from >>>> its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late >>>> times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
IÂ’ve used them a fair amount in front ends, generally with a SiGe NPN
cascode-slash-drain bootstrap. Their transconductance is a few times
higher than a CPH3910Â’s, but not as good as the local-feedback circuitÂ’s. >>
pHEMTs have very low drain impedance—the late lamented ATF38143 had a
voltage gain of ~0.7 as a follower, even with a current sink in the tail.
Their amazing noise floor (~0.3 nV in 1 Hz) makes them well worth patching >> up, but they do take some patching.
Cheers
Phil Hobbs
What is the Vdd in your circuit above?
I learned about jfet impact ionization from AoE. Keep the drain
voltage low!
john larkin <jl@650pot.com> wrote:
On Thu, 5 Sep 2024 22:44:36 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@650pot.com> wrote:
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>>>>> protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
Thanks. It?s not a 50-ohm system, so using those would be hard. I have >>>>>>> thousands for personal use, but can?t put them in licensed designs, which
is what I?m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise >>>>>> things around. Just because the RF boys test everything at 50 ohms >>>>>> doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of, >>>>>
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot >>>>> without adding much noise at all--way better than an NPN follower after >>>>> the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz >>>>> device, so a 5-GHz PNP is great. The alternative would be a 100-MHz >>>>> PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped >>>>> version of the White cathode follower, where the feedback is applied via >>>>> the tail source. That's much harder to stabilize, because there are >>>>> three transistors in the local feedback loop, but on the other hand its >>>>> gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from >>>>> its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of >>>>> 0.9, but that extra 10% shows up as a gnarly settling transient at late >>>>> times, which screws up measurements. 0.9997 is dramatically better. >>>>>
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
IÂ’ve used them a fair amount in front ends, generally with a SiGe NPN
cascode-slash-drain bootstrap. Their transconductance is a few times
higher than a CPH3910Â’s, but not as good as the local-feedback circuitÂ’s. >>>
pHEMTs have very low drain impedance—the late lamented ATF38143 had a
voltage gain of ~0.7 as a follower, even with a current sink in the tail. >>>
Their amazing noise floor (~0.3 nV in 1 Hz) makes them well worth patching >>> up, but they do take some patching.
Cheers
Phil Hobbs
What is the Vdd in your circuit above?
I learned about jfet impact ionization from AoE. Keep the drain
voltage low!
Yup. I run them between 2.5 and 3 V_DS.
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
If most your designs are similar enough, perhaps you can consilidate it
into a single version and persuade Analog Devices to make it on their
XFCB3 process, either if you pay NRE and the design belongs to you, sold
as a custom part that they can only sell via you, or that they sell
themself and somehow give you a royalty. If you had a patent it might
help with that negotiation.
On 5/09/2024 7:54 am, Phil Hobbs wrote:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno
who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
If most your designs are similar enough, perhaps you can consilidate it
into a single version and persuade Analog Devices to make it on their
XFCB3 process, either if you pay NRE and the design belongs to you, sold
as a custom part that they can only sell via you, or that they sell
themself and somehow give you a royalty. If you had a patent it might
help with that negotiation.
The other option I can imagine is that there might be a fab in China
capable of makine fast PNPs and who might find some pride in selling a
faster PNP than any western company does.
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
On 9/4/24 2:54 PM, Phil Hobbs wrote:
The NTE2403, similar to the BFT92, but a bit better overall.ÿ Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Some of the good stuff is going away because there aren't many people
left who know how to use it and then trigger substantial sales.
How about the HFA3135 pair? Less noisy than the HFA3096 but not sure if
good enough for your projects:
https://www.renesas.com/us/en/document/dst/hfa3134-hfa3135-datasheet?r=532781
They are long leadtime and pricey though, often around 10 bucks.
Currently 18 weeks which often is code for "could be half a year", or so ...
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >>>>>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay. >>>>>
Thanks. It’s not a 50-ohm system, so using those would be hard. I have >>>> thousands for personal use, but can’t put them in licensed designs, which
is what I’m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise
things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of,
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot
without adding much noise at all--way better than an NPN follower after
the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via
the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its
gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from
its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late
times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
On 9/5/2024 6:06 PM, john larkin wrote:
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who >>>>>>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
Thanks. It’s not a 50-ohm system, so using those would be hard. I have >>>>> thousands for personal use, but can’t put them in licensed designs, which
is what I’m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise
things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of, >>>
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot
without adding much noise at all--way better than an NPN follower after
the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via >>> the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its
gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from >>> its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late
times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
What about a PFET/JEFT cascode buffer kinda like:
<https://imgur.com/a/5fBR8Gb>
bitrex <user@example.net> wrote:
On 9/5/2024 6:06 PM, john larkin wrote:
On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2024-09-05 10:14, john larkin wrote:
On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Jan Panteltje <alien@comet.invalid> wrote:
On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs >>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
<6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20 >>>>>>>> cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for >>>>>>>> protos and small production, but I can't use PNP wraparound bootstraps >>>>>>>> for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
Lots if RF snall signal low noise stoff in LNBs:
https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
Does that help?
Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
Thanks. It’s not a 50-ohm system, so using those would be hard. I have
thousands for personal use, but can’t put them in licensed designs, which
is what I’m moaning about.
Cheers
Phil Hobbs
Can you use mmics? There are some really cool, fast, cheap, low-noise >>>>> things around. Just because the RF boys test everything at 50 ohms
doesn't mean we have to use them at 50 ohms.
For the wraparound topology, which is the second-best follower I know of, >>>>
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot >>>> without adding much noise at all--way better than an NPN follower after >>>> the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via >>>> the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its >>>> gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from >>>> its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late >>>> times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
The CPH3910 is a jfet. Might an un-assisted PHEMT be better?
What about a PFET/JEFT cascode buffer kinda like:
<https://imgur.com/a/5fBR8Gb>
There aren’t any decent discrete pfets left, and there never was a 5 GHz one.
Joerg <news@analogconsultants.com> wrote:
On 9/4/24 2:54 PM, Phil Hobbs wrote:
The NTE2403, similar to the BFT92, but a bit better overall.� Dunno who >>> actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Some of the good stuff is going away because there aren't many people
left who know how to use it and then trigger substantial sales.
How about the HFA3135 pair? Less noisy than the HFA3096 but not sure if
good enough for your projects:
https://www.renesas.com/us/en/document/dst/hfa3134-hfa3135-datasheet?r=532781
They are long leadtime and pricey though, often around 10 bucks.
Currently 18 weeks which often is code for "could be half a year", or so ... >>
Suggesting a $10 boutique part? Who are you, and what have you done with Joerg S-C?
;)
The NTE2403, similar to the BFT92, but a bit better overall. Dunno who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Cheers
Phil Hobbs
On 2024-09-04 17:54, Phil Hobbs wrote:
The NTE2403, similar to the BFT92, but a bit better overall. Dunno
who actually made them. (I saw the news on s.e.repair today.)
Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
cents, but that's all she wrote.
I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
protos and small production, but I can't use PNP wraparound bootstraps
for customer designs anymore. :(
Barstids.
Something like this. This is what I call a Type 2 bootstrap, in which
the bootstrap device is inside the TIA feedback loop. You have to worry about drift and 1/f noise in the FET, but that's usually the least of
your worries.
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