>Am 31.01.19 um 14:15 schrieb 698839253X6D445TD@nospam.org:
>
>>>
>>> In this app note, they mention that they have pretty accurate models
>>>
>>> <
>>>
>>> https://www.wolfspeed.com/downloads/dl/file/id/847/product/159/load_pull_validation_of_large_signal_cree_gan_field_effect_transis
>>> tor_fet_model.pdf
>>> >
>>>
>>> but it takes a harmonic balance simulator, so el cheapo LTspice won't
>>> cut it. Buy a copy of ADS, for 100K +-.
>>>
>>> regards, Gerhard
>>
>> Yea,
>> well I thought :
>> 'Must be extremely nonlinear or large production spread else they would publish it'.
>>
>
>No, just the opposite. The only important market for these is cell phone
>base stations and to avoid spectral regrowth and for efficiency reasons
>they need at least Doherty amplifiers, preferably with a monitoring
>receiver and active predistortion. Just take a look at ADI's fastest
>ADCs with GHz sample rates and what they are made for.
OK, but I wrote that because you never know if they read this group and would then publish it ;-)
>You cannot make that with LTspice, it takes ADS or Microwave office.
>The data sheets are just teasers, you don't get far without their
>engineering pack.
I need to get some experience with those FETS, really.
There is a lot of those new parts that I have no hand on experience with yet,
not needed those till now.
>I once did some design work on a base station, regretfully on it's
>CPU and not the RF section. The customer made it clear that every �
>on the BOM would have to be multiplied by 10 Meg over the product
>lifetime.
>Even Xilinx insisted they would never ever lose the design-in on price.
>Shocking, those numbers. Even J�rg would have felt challenged.
I bought mine in 2014, the Es'hail-2 was delayed many times.....
So the thing landed, after testing with a dummy load, in the storage too.
Anyways cellphone tower are sort of interesting in many ways,,,
Maybe even more so now 5G coming.
Reply by Gerhard Hoffmann●January 31, 20192019-01-31
Am 31.01.19 um 14:15 schrieb 698839253X6D445TD@nospam.org:
No, just the opposite. The only important market for these is cell phone
base stations and to avoid spectral regrowth and for efficiency reasons
they need at least Doherty amplifiers, preferably with a monitoring
receiver and active predistortion. Just take a look at ADI's fastest
ADCs with GHz sample rates and what they are made for.
You cannot make that with LTspice, it takes ADS or Microwave office.
The data sheets are just teasers, you don't get far without their
engineering pack.
I once did some design work on a base station, regretfully on it's
CPU and not the RF section. The customer made it clear that every �
on the BOM would have to be multiplied by 10 Meg over the product
lifetime.
Even Xilinx insisted they would never ever lose the design-in on price.
Shocking, those numbers. Even J�rg would have felt challenged.
You could have got mine. I bought it for AO-40, the one with the strong
elliptical orbit. When it turned out that it would never fly, the
amplifier strip disappeared somewhere in the basement.
One of my worst investments.
73, Gerhard
Reply by John Larkin●January 30, 20192019-01-30
On Wed, 30 Jan 2019 14:23:02 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:
>On Wednesday, January 30, 2019 at 11:48:35 AM UTC-8, John Larkin wrote:
>
>> The eval boards just bring out the gate bias as a pin and assume users
>> will magically know how to set that.
>
>Yeah, crank it up til it emits magic smoke, then twenty percent
>less...
It's not obvious what polarity the bias should be.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by whit3rd●January 30, 20192019-01-30
On Wednesday, January 30, 2019 at 11:48:35 AM UTC-8, John Larkin wrote:
> The eval boards just bring out the gate bias as a pin and assume users
> will magically know how to set that.
Yeah, crank it up til it emits magic smoke, then twenty percent
less...
Reply by John Larkin●January 30, 20192019-01-30
On Tue, 29 Jan 2019 20:58:02 -0800 (PST), dagmargoodboat@yahoo.com
wrote:
>On Thursday, January 17, 2019 at 4:52:13 PM UTC-5, Gerhard Hoffmann wrote:
>> Am 12.01.19 um 06:39 schrieb dagmargoodboat@yahoo.com:
>>
>> > One of my problems, currently, is that most of the high-voltage fancy
>> > FETs are monstrous compared to my needs, so even though their figures-
>> > of-merit Ron vs. Qg are worlds better than the older tech stuff, the
>> > fact that they're 20x over-sized for my application makes them slower
>> > than an appropriately-sized MOSFET.
>> >
>> > Even the most nimble GaN garbage truck FET still isn't as gamely as a
>> > silicon itty bitty unicycle FET.
>>
>> A bit smaller than the other transistors that were mentioned,
>> but nevertheless DC to 6 GHz:
>>
>> < https://www.mouser.de/datasheet/2/90/ghv27030s-947886.pdf >
>>
>> A nice driver, at least :-)
>>
>> Cheers,
>> Gerhard
>
>Wow, that's one beast of a driver ;-)
>
>Cheers,
>James Arthur
It's a typical RF data sheet: primitive DC specs and no DC curves at
all.
The eval boards just bring out the gate bias as a pin and assume users
will magically know how to set that.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by ●January 30, 20192019-01-30
On Thursday, January 17, 2019 at 4:52:13 PM UTC-5, Gerhard Hoffmann wrote:
> Am 12.01.19 um 06:39 schrieb dagmargoodboat@yahoo.com:
>
> > One of my problems, currently, is that most of the high-voltage fancy
> > FETs are monstrous compared to my needs, so even though their figures-
> > of-merit Ron vs. Qg are worlds better than the older tech stuff, the
> > fact that they're 20x over-sized for my application makes them slower
> > than an appropriately-sized MOSFET.
> >
> > Even the most nimble GaN garbage truck FET still isn't as gamely as a
> > silicon itty bitty unicycle FET.
>
> A bit smaller than the other transistors that were mentioned,
> but nevertheless DC to 6 GHz:
>
> < https://www.mouser.de/datasheet/2/90/ghv27030s-947886.pdf >
>
> A nice driver, at least :-)
>
> Cheers,
> Gerhard
Wow, that's one beast of a driver ;-)
Cheers,
James Arthur
Reply by Gerhard Hoffmann●January 17, 20192019-01-17
Am 12.01.19 um 06:39 schrieb dagmargoodboat@yahoo.com:
> One of my problems, currently, is that most of the high-voltage fancy
> FETs are monstrous compared to my needs, so even though their figures-
> of-merit Ron vs. Qg are worlds better than the older tech stuff, the
> fact that they're 20x over-sized for my application makes them slower
> than an appropriately-sized MOSFET.
>
> Even the most nimble GaN garbage truck FET still isn't as gamely as a
> silicon itty bitty unicycle FET.
On Mon, 14 Jan 2019 10:13:11 +1100, Clifford Heath
<no.spam@please.net> wrote:
>On 13/1/19 6:55 am, Winfield Hill wrote:
>> dagmargoodboat@yahoo.com wrote...
>>>
>>> Winfield Hill wrote:
>>>>
>>>> There's very little in the signal path. And the 20ns delay to
>>>> *the MOSFET output* is about as fast as you'll find. My only
>>>> complaint is that the FETs are too big, too much capacitance.
>>>> When switching a 50-ohm cable-matching output resistor, a low
>>>> 70-milli-ohm Ron is serious overkill.
>>>
>>> Hey Win, here's a smaller-sized version of the same concept,
>>> driver-plus-GaN on a chip:
>>> <https://media.digikey.com/pdf/Data%20Sheets/Navitas%20Semi%20PDFs/NV6113%20Datasheet%20(FINAL)%208-28-18.pdf>
>>
>> Wow, Navitas NV6113, GaN, 200V/ns, only $3.38 at Digi-Key. And
>> Octopart doesn't even know about them yet! It looks hard to get
>> heat out of the package, they say limited to 2MHz switching rate.
>
>50C/W - ugly. That would practically limit you to about 2 amps average,
>at 300mOhm. That's just not... special.
It might make sense thermally to parallel a few smaller parts, EPC
GaNs or these things.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
Reply by ●January 13, 20192019-01-13
On Sunday, January 13, 2019 at 6:13:19 PM UTC-5, Clifford Heath wrote:
> On 13/1/19 6:55 am, Winfield Hill wrote:
> > dagmargoodboat@yahoo.com wrote...
> >>
> >> Winfield Hill wrote:
> >>>
> >>> There's very little in the signal path. And the 20ns delay to
> >>> *the MOSFET output* is about as fast as you'll find. My only
> >>> complaint is that the FETs are too big, too much capacitance.
> >>> When switching a 50-ohm cable-matching output resistor, a low
> >>> 70-milli-ohm Ron is serious overkill.
> >>
> >> Hey Win, here's a smaller-sized version of the same concept,
> >> driver-plus-GaN on a chip:
> >> <https://media.digikey.com/pdf/Data%20Sheets/Navitas%20Semi%20PDFs/NV6113%20Datasheet%20(FINAL)%208-28-18.pdf>
> >
> > Wow, Navitas NV6113, GaN, 200V/ns, only $3.38 at Digi-Key. And
> > Octopart doesn't even know about them yet! It looks hard to get
> > heat out of the package, they say limited to 2MHz switching rate.
>
> 50C/W - ugly. That would practically limit you to about 2 amps average,
> at 300mOhm. That's just not... special.
Au contraire! Two amps is way more than I need, and I much appreciate
the reduced capacitances. (Not all of us are trying to drive big metal
all the time, or launch EMI out into space. :)
There are lots of big wide-gap devices for big-power stuff. But we
don't have many choices yet when it comes to making a dinky lil'
signal generator.
Cheers,
James Arthur
Reply by Clifford Heath●January 13, 20192019-01-13
On 13/1/19 6:55 am, Winfield Hill wrote:
> dagmargoodboat@yahoo.com wrote...
>>
>> Winfield Hill wrote:
>>>
>>> There's very little in the signal path. And the 20ns delay to
>>> *the MOSFET output* is about as fast as you'll find. My only
>>> complaint is that the FETs are too big, too much capacitance.
>>> When switching a 50-ohm cable-matching output resistor, a low
>>> 70-milli-ohm Ron is serious overkill.
>>
>> Hey Win, here's a smaller-sized version of the same concept,
>> driver-plus-GaN on a chip:
>> <https://media.digikey.com/pdf/Data%20Sheets/Navitas%20Semi%20PDFs/NV6113%20Datasheet%20(FINAL)%208-28-18.pdf>
>
> Wow, Navitas NV6113, GaN, 200V/ns, only $3.38 at Digi-Key. And
> Octopart doesn't even know about them yet! It looks hard to get
> heat out of the package, they say limited to 2MHz switching rate.
50C/W - ugly. That would practically limit you to about 2 amps average,
at 300mOhm. That's just not... special.