Does anyone know where to get models for the really big fat base station transistors? Right now it doesn't matter which mfg. NXP doesn't seem to have one for the BLF878 anymore, somehow gone, I'll have to ask where it went. Anyhow, they only provide scant information and only at particular bias points, like these:
On Thu, 09 Jul 2009 17:38:30 -0700, Joerg <inva...@invalid.invalid> wrote:
>Hello Newsgroup,
>Does anyone know where to get models for the really big fat base station >transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >have one for the BLF878 anymore, somehow gone, I'll have to ask where it >went. Anyhow, they only provide scant information and only at particular >bias points, like these:
>I need something real, something I can plug into LTSpice.
Why? Did something go *Phut* again ?:-)
...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
Jim Thompson wrote: > On Thu, 09 Jul 2009 17:38:30 -0700, Joerg <inva...@invalid.invalid> > wrote:
>> Hello Newsgroup,
>> Does anyone know where to get models for the really big fat base station >> transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >> have one for the BLF878 anymore, somehow gone, I'll have to ask where it >> went. Anyhow, they only provide scant information and only at particular >> bias points, like these:
>> I need something real, something I can plug into LTSpice.
> Why? Did something go *Phut* again ?:-)
No, but I want to make sure it's all kosher because a *phut* situation could become rather ugly if you combine a dozen of those. Molten solder splattering about, blaring sirens ...
> Does anyone know where to get models for the really big fat base station > transistors? Right now it doesn't matter which mfg. NXP doesn't seem to > have one for the BLF878 anymore, somehow gone, I'll have to ask where it > went. Anyhow, they only provide scant information and only at particular > bias points, like these:
> I need something real, something I can plug into LTSpice.
So, guys, got an answer from NXP: They do not create SPICE models for their RF products. They only create ADS models.
I assume ADS only works with EEsof which probably still costs the equivalent of a nice car and I bet models are not convertible. Great. Cuts off much of the secondary users for their RF transistors. What were they thinking?
Oh, and the support email says you cannot reply to the message. Oh man, now that they've got their web site in order it starts to crumble somewhere else.
>> Does anyone know where to get models for the really big fat base station >> transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >> have one for the BLF878 anymore, somehow gone, I'll have to ask where it >> went. Anyhow, they only provide scant information and only at particular >> bias points, like these:
>> I need something real, something I can plug into LTSpice.
>So, guys, got an answer from NXP: They do not create SPICE models for >their RF products. They only create ADS models.
>I assume ADS only works with EEsof which probably still costs the >equivalent of a nice car and I bet models are not convertible. Great. >Cuts off much of the secondary users for their RF transistors. What were >they thinking?
>Oh, and the support email says you cannot reply to the message. Oh man, >now that they've got their web site in order it starts to crumble >somewhere else.
Sounds like it's a Curtice model... works in PSpice ;-)
...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
Jim Thompson wrote: > On Fri, 10 Jul 2009 14:52:14 -0700, Joerg <inva...@invalid.invalid> > wrote:
>> Joerg wrote: >>> Hello Newsgroup,
>>> Does anyone know where to get models for the really big fat base station >>> transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >>> have one for the BLF878 anymore, somehow gone, I'll have to ask where it >>> went. Anyhow, they only provide scant information and only at particular >>> bias points, like these:
>>> I need something real, something I can plug into LTSpice.
>> So, guys, got an answer from NXP: They do not create SPICE models for >> their RF products. They only create ADS models.
>> I assume ADS only works with EEsof which probably still costs the >> equivalent of a nice car and I bet models are not convertible. Great. >> Cuts off much of the secondary users for their RF transistors. What were >> they thinking?
>> Oh, and the support email says you cannot reply to the message. Oh man, >> now that they've got their web site in order it starts to crumble >> somewhere else.
> Sounds like it's a Curtice model... works in PSpice ;-)
But LTSpice wants LGATE, RGATE, CG, CRSS, CISS, LS, CS ... and so on :-(
I plan to use it in a quite unorthodox application (like usual ...).
>>>> Does anyone know where to get models for the really big fat base station >>>> transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >>>> have one for the BLF878 anymore, somehow gone, I'll have to ask where it >>>> went. Anyhow, they only provide scant information and only at particular >>>> bias points, like these:
>>>> I need something real, something I can plug into LTSpice.
>>> So, guys, got an answer from NXP: They do not create SPICE models for >>> their RF products. They only create ADS models.
>>> I assume ADS only works with EEsof which probably still costs the >>> equivalent of a nice car and I bet models are not convertible. Great. >>> Cuts off much of the secondary users for their RF transistors. What were >>> they thinking?
>>> Oh, and the support email says you cannot reply to the message. Oh man, >>> now that they've got their web site in order it starts to crumble >>> somewhere else.
>> Sounds like it's a Curtice model... works in PSpice ;-)
>But LTSpice wants LGATE, RGATE, CG, CRSS, CISS, LS, CS ... and so on :-(
>I plan to use it in a quite unorthodox application (like usual ...).
I would guess someone here with an IEEE membership can locate a translator.
(The Curtice model is built into PSpice... primary use: GaAs FET's)
...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
On 10 Jul., 02:38, Joerg <inva...@invalid.invalid> wrote:
> Hello Newsgroup,
> Does anyone know where to get models for the really big fat base station > transistors? Right now it doesn't matter which mfg. NXP doesn't seem to > have one for the BLF878 anymore, somehow gone, I'll have to ask where it > went. Anyhow, they only provide scant information and only at particular > bias points, like these:
Jim Thompson wrote: > On Sat, 11 Jul 2009 09:20:44 -0700, Joerg <inva...@invalid.invalid> > wrote:
>> Jim Thompson wrote: >>> On Fri, 10 Jul 2009 14:52:14 -0700, Joerg <inva...@invalid.invalid> >>> wrote:
>>>> Joerg wrote: >>>>> Hello Newsgroup,
>>>>> Does anyone know where to get models for the really big fat base station >>>>> transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >>>>> have one for the BLF878 anymore, somehow gone, I'll have to ask where it >>>>> went. Anyhow, they only provide scant information and only at particular >>>>> bias points, like these:
>>>>> I need something real, something I can plug into LTSpice.
>>>> So, guys, got an answer from NXP: They do not create SPICE models for >>>> their RF products. They only create ADS models.
>>>> I assume ADS only works with EEsof which probably still costs the >>>> equivalent of a nice car and I bet models are not convertible. Great. >>>> Cuts off much of the secondary users for their RF transistors. What were >>>> they thinking?
>>>> Oh, and the support email says you cannot reply to the message. Oh man, >>>> now that they've got their web site in order it starts to crumble >>>> somewhere else. >>> Sounds like it's a Curtice model... works in PSpice ;-)
>> But LTSpice wants LGATE, RGATE, CG, CRSS, CISS, LS, CS ... and so on :-(
>> I plan to use it in a quite unorthodox application (like usual ...).
> I would guess someone here with an IEEE membership can locate a > translator.
I am a member but they nickel and dime you for access to just about everything not in your subscribed societies, so probably no access to what's needed. But thanks for the info, gives me pointers how to search on the web.
> (The Curtice model is built into PSpice... primary use: GaAs FET's)
Somehow it doesn't look like the Curtice model on page 8-103 of this Agilent doc though:
>> Does anyone know where to get models for the really big fat base station >> transistors? Right now it doesn't matter which mfg. NXP doesn't seem to >> have one for the BLF878 anymore, somehow gone, I'll have to ask where it >> went. Anyhow, they only provide scant information and only at particular >> bias points, like these:
>> I need something real, something I can plug into LTSpice.
> think I have seen somewhere (yahoo forum?) that someone got a model > like > that into ltspice but it wouldn't work for transient analysis.
Haven't found anything there but will keep looking elsewhere. However, transient analysis is exactly what I am after, I am not using it as a regular RF amp.
> what kind of transistor specs are you looking for?, ...
As big a honking RF power transistor as possible, good up to a GHz, or at least lower UHF. I am prepared to live with whatever specs they've got, pretty slim pickens up there anyhow because the market for this stuff is small. But I'd need a somewhat proper SPICE model. This kind of circuitry has to be simulated pretty well, trying it all on the bench can lead to lots of molten solder splattering around, a loud bang, smoke, ferrite pieces flying all over the place and so on.
> ... I've seen models for other > big rf transistors that work in lspice somewhere.
Yes, PolyFet has some but this looks like high-price specialty parts. I was hoping for a more mainstream part from a bis semi mfg.
> Joerg, OK now I know a little bit more of what you are > looking for.
> What frequency range are you looking for?
Devices that can do up to lower UHF, 500MHz or so, with decent efficiency would be fine. Tons of power ;-)
> Freescale has some LDMOS chips in the > 500 - 1500 MHz range.
> Cree and Nitronex have GaN chips which > use the MCM SPICE models
Yes, but even the Nitronex flagship NPT1007 can only do around 100W. I am looking for something that can stomach a few hundred watts. PolyFet has one, not quite like the big BLF but close and at least they give out SPICE parameters.
On Sat, 11 Jul 2009 12:08:03 -0700, Joerg <inva...@invalid.invalid> wrote: >As big a honking RF power transistor as possible, good up to a GHz, or >at least lower UHF. I am prepared to live with whatever specs they've >got, pretty slim pickens up there anyhow because the market for this >stuff is small. But I'd need a somewhat proper SPICE model. This kind of >circuitry has to be simulated pretty well,
I looked into that some years ago when I still was interested in fat RF transistors and the consensus was that Spice doesn't cut it for this application. There were models from Moto/Freescale/On/MaCom and Philips/NXP, but only for ADS, Microwave Office and Harbec/Genesys/Eagleware (that is now Agilent, too). These simulators had been specially enhanced to digest these models. IIRC it was a real physics problem, maybe local themal effects.
Sorry, that means $$$.
>trying it all on the bench >can lead to lots of molten solder splattering around, a loud bang, >smoke, ferrite pieces flying all over the place and so on.
Gerhard Hoffmann wrote: > On Sat, 11 Jul 2009 12:08:03 -0700, Joerg <inva...@invalid.invalid> wrote:
>> As big a honking RF power transistor as possible, good up to a GHz, or >> at least lower UHF. I am prepared to live with whatever specs they've >> got, pretty slim pickens up there anyhow because the market for this >> stuff is small. But I'd need a somewhat proper SPICE model. This kind of >> circuitry has to be simulated pretty well,
> I looked into that some years ago when I still was interested in > fat RF transistors and the consensus was that Spice doesn't cut it > for this application. There were models from Moto/Freescale/On/MaCom > and Philips/NXP, but only for ADS, Microwave Office and Harbec/Genesys/Eagleware > (that is now Agilent, too). These simulators had been specially > enhanced to digest these models. IIRC it was a real physics problem, > maybe local themal effects.
Actually about an hour ago I simulated the first such power transistor, a 300W VHF device from PolyFet because they furnish a fairly elaborate SPICE model. It is a subcircuit with three different semiconductor models and numerous discretes in there. So far it shows all the nasties you see with VHF broadband stuff in the real world, meaning it can't be too far from the real world. I have designed lots of power pulsers in my life, all under 15nsec though and it seems that going to 5nsec make the unwanted stuff grow 10x :-(
> Sorry, that means $$$.
Yep, and that's not (yet) in the budget for this project. Also, those simulators are geared towards RF stages that run continuous duty. Mine will be pulsed pretty brutally, so hardcore time domain sims are needed.
Now I am trying to figure out a VSWR protection that acts within a few nanoseconds ...
On Sat, 18 Jul 2009 14:57:39 -0700, Joerg <inva...@invalid.invalid> wrote: >Actually about an hour ago I simulated the first such power transistor, >a 300W VHF device from PolyFet because they furnish a fairly elaborate >SPICE model. It is a subcircuit with three different semiconductor >models and numerous discretes in there. So far it shows all the nasties >you see with VHF broadband stuff in the real world, meaning it can't be >too far from the real world. I have designed lots of power pulsers in my >life, all under 15nsec though and it seems that going to 5nsec make the >unwanted stuff grow 10x :-(
>> Sorry, that means $$$.
>Yep, and that's not (yet) in the budget for this project. Also, those >simulators are geared towards RF stages that run continuous duty. Mine >will be pulsed pretty brutally, so hardcore time domain sims are needed.
>Now I am trying to figure out a VSWR protection that acts within a few >nanoseconds ...
IIRC, these fat FETs had a memory effect, i.e. they behaved differently wrt what happened some us/ms before.
Gerhard Hoffmann wrote: > On Sat, 18 Jul 2009 14:57:39 -0700, Joerg <inva...@invalid.invalid> wrote:
>> Actually about an hour ago I simulated the first such power transistor, >> a 300W VHF device from PolyFet because they furnish a fairly elaborate >> SPICE model. It is a subcircuit with three different semiconductor >> models and numerous discretes in there. So far it shows all the nasties >> you see with VHF broadband stuff in the real world, meaning it can't be >> too far from the real world. I have designed lots of power pulsers in my >> life, all under 15nsec though and it seems that going to 5nsec make the >> unwanted stuff grow 10x :-(
>>> Sorry, that means $$$.
>> Yep, and that's not (yet) in the budget for this project. Also, those >> simulators are geared towards RF stages that run continuous duty. Mine >> will be pulsed pretty brutally, so hardcore time domain sims are needed.
>> Now I am trying to figure out a VSWR protection that acts within a few >> nanoseconds ...
> IIRC, these fat FETs had a memory effect, i.e. they behaved differently > wrt what happened some us/ms before.
There are some local heating issues, definitely at the power level I am dealing with. But it could be worse: The old BJTs had sort of a ROM effect. Treat them too harshly and one of more of the emitter paths would go phsst ... *phut* ... and then your transistor would deliver only half the power from here on. Forever, it would not fix itself anymore. I've used such a partially damaged transistor that was down to 60% of nominal in a 2m transceiver for over a decade, that used one was all my student's budget would allow (dipping into the beer budget was not an option ...).
>>Actually about an hour ago I simulated the first such power transistor, >>a 300W VHF device from PolyFet because they furnish a fairly elaborate >>SPICE model. It is a subcircuit with three different semiconductor >>models and numerous discretes in there. So far it shows all the nasties >>you see with VHF broadband stuff in the real world, meaning it can't be >>too far from the real world. I have designed lots of power pulsers in my >>life, all under 15nsec though and it seems that going to 5nsec make the >>unwanted stuff grow 10x :-(
>>> Sorry, that means $$$.
>>Yep, and that's not (yet) in the budget for this project. Also, those >>simulators are geared towards RF stages that run continuous duty. Mine >>will be pulsed pretty brutally, so hardcore time domain sims are needed.
>>Now I am trying to figure out a VSWR protection that acts within a few >>nanoseconds ...
>IIRC, these fat FETs had a memory effect, i.e. they behaved differently >wrt what happened some us/ms before.
>G.
That sounds a lot like what some might call thermal inertial. Of course you might want to model it as a thermal array device to get closer to the actual operating physics.
You might to reconsider the decision to build a switch to measure VSWR.
You might want to look at gradually decreasing power as the VSWR goes up. If you switch everything at once, you will have a very large arc as the power has to go somewhere ( usually a place that you don't want it to) There are companies out there that make VSWR protection circuits but they have be integrated into the PA in some fashion.
> You might to reconsider the decision to build a switch to measure > VSWR.
> You might want to look at gradually decreasing power as the VSWR goes > up. > If you switch everything at once, you will have a very large arc as > the power has to > go somewhere ( usually a place that you don't want it to) > There are companies out there that make VSWR protection circuits but > they > have be integrated into the PA in some fashion.
I can't go gradual because the switch action is what will actually happen in this application. Near-shorts, full and sudden interruption, and so on. It needs to survive that. The usual SWR protection circuits rely on bridges, multipliers and whatnot, typically after rectifying the phase-coupler outputs. By the time the rectified signals show up it'll already be ... phut ... *KABLAM*
