Forums

NE3509 SPICE model?

Started by Joerg September 6, 2011
Gents,

Does anyone know where to find the SPICE model for the NE3509? Or at
least one that's close enough for pulse stuff? CEL only has the usual
microwave models but I want to use it as a fast low capacitance switch
and simulate in LTSpice.

-- 
Regards, Joerg

http://www.analogconsultants.com/
On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Gents, > >Does anyone know where to find the SPICE model for the NE3509? Or at >least one that's close enough for pulse stuff? CEL only has the usual >microwave models but I want to use it as a fast low capacitance switch >and simulate in LTSpice.
Have you asked NEC/CEL? The datasheets aren't bad, for an RF phemt. There are actual DC curves! We use them as fast switches, and I took a bunch of data - capacitances, Ron at various biases, tempco, extended DC curves - and I'll email you what I have. Some of my data is for NE3508, same thing but twice as big. No Spice model. They appear to behave like jfets, in that you can ground the source and have the drain swing negative so long as you keep the gate suitably negative. They also enhance to many times the zero-gate-voltage conductance, numbers like 4 and 2 ohms Rds-on for the respective parts. Cute parts. I hope NEC keeps making them. John
John Larkin wrote:
> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Gents, >> >> Does anyone know where to find the SPICE model for the NE3509? Or at >> least one that's close enough for pulse stuff? CEL only has the usual >> microwave models but I want to use it as a fast low capacitance switch >> and simulate in LTSpice. > > Have you asked NEC/CEL? >
I haven't. Was in a rush and have plopped down a Calogic DS-series part because I know it can do the job in this case. But I'd like to be able to use the NE3509 in the future or in case things need to be even faster.
> The datasheets aren't bad, for an RF phemt. There are actual DC > curves! > > We use them as fast switches, and I took a bunch of data - > capacitances, Ron at various biases, tempco, extended DC curves - and > I'll email you what I have. Some of my data is for NE3508, same thing > but twice as big. No Spice model. > > They appear to behave like jfets, in that you can ground the source > and have the drain swing negative so long as you keep the gate > suitably negative. > > They also enhance to many times the zero-gate-voltage conductance, > numbers like 4 and 2 ohms Rds-on for the respective parts. >
That sounds like a white knuckle ride :-)
> Cute parts. I hope NEC keeps making them. >
Yes, so do I. There are lots of RF parts that can be used in pulse apps but other than companies like PolyFet it can be tough to get SPICE models. -- Regards, Joerg http://www.analogconsultants.com/
On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid>
wrote:

>John Larkin wrote: >> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> Gents, >>> >>> Does anyone know where to find the SPICE model for the NE3509? Or at >>> least one that's close enough for pulse stuff? CEL only has the usual >>> microwave models but I want to use it as a fast low capacitance switch >>> and simulate in LTSpice. >> >> Have you asked NEC/CEL? >> > >I haven't. Was in a rush and have plopped down a Calogic DS-series part >because I know it can do the job in this case. But I'd like to be able >to use the NE3509 in the future or in case things need to be even faster.
Do you need a Spice model? As switches, these things are pretty simple.
> > >> The datasheets aren't bad, for an RF phemt. There are actual DC >> curves! >> >> We use them as fast switches, and I took a bunch of data - >> capacitances, Ron at various biases, tempco, extended DC curves - and >> I'll email you what I have. Some of my data is for NE3508, same thing >> but twice as big. No Spice model. >> >> They appear to behave like jfets, in that you can ground the source >> and have the drain swing negative so long as you keep the gate >> suitably negative. >> >> They also enhance to many times the zero-gate-voltage conductance, >> numbers like 4 and 2 ohms Rds-on for the respective parts. >> > >That sounds like a white knuckle ride :-)
No, just bias the gate a few tenth of a volt positive. Works great. John
John Larkin wrote:
> On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >>> wrote: >>> >>>> Gents, >>>> >>>> Does anyone know where to find the SPICE model for the NE3509? Or at >>>> least one that's close enough for pulse stuff? CEL only has the usual >>>> microwave models but I want to use it as a fast low capacitance switch >>>> and simulate in LTSpice. >>> Have you asked NEC/CEL? >>> >> I haven't. Was in a rush and have plopped down a Calogic DS-series part >> because I know it can do the job in this case. But I'd like to be able >> to use the NE3509 in the future or in case things need to be even faster. > > Do you need a Spice model? As switches, these things are pretty > simple. >
Yes, I do need a model. Reason is that things like Cgd versus channel resistance matter. I was in a hurry so used Calogic parts now, good enough for this application. There is a 2nd source (well, sorta) and there is a SPICE model. This is a very fast switching app where slopes and ringout behavior matter.
>> >>> The datasheets aren't bad, for an RF phemt. There are actual DC >>> curves! >>> >>> We use them as fast switches, and I took a bunch of data - >>> capacitances, Ron at various biases, tempco, extended DC curves - and >>> I'll email you what I have. Some of my data is for NE3508, same thing >>> but twice as big. No Spice model. >>> >>> They appear to behave like jfets, in that you can ground the source >>> and have the drain swing negative so long as you keep the gate >>> suitably negative. >>> >>> They also enhance to many times the zero-gate-voltage conductance, >>> numbers like 4 and 2 ohms Rds-on for the respective parts. >>> >> That sounds like a white knuckle ride :-) > > No, just bias the gate a few tenth of a volt positive. Works great. >
Ok, I'd dare to go to 300mV. But any closer is scary. -- Regards, Joerg http://www.analogconsultants.com/
On Tue, 06 Sep 2011 17:53:22 -0700, Joerg <invalid@invalid.invalid>
wrote:

>John Larkin wrote: >> On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >>>> wrote: >>>> >>>>> Gents, >>>>> >>>>> Does anyone know where to find the SPICE model for the NE3509? Or at >>>>> least one that's close enough for pulse stuff? CEL only has the usual >>>>> microwave models but I want to use it as a fast low capacitance switch >>>>> and simulate in LTSpice. >>>> Have you asked NEC/CEL? >>>> >>> I haven't. Was in a rush and have plopped down a Calogic DS-series part >>> because I know it can do the job in this case. But I'd like to be able >>> to use the NE3509 in the future or in case things need to be even faster. >> >> Do you need a Spice model? As switches, these things are pretty >> simple. >> > >Yes, I do need a model. Reason is that things like Cgd versus channel >resistance matter. I was in a hurry so used Calogic parts now, good >enough for this application. There is a 2nd source (well, sorta) and >there is a SPICE model.
The 3509 has a drain capacitance, mostly to the source, that's fairly constant at about 0.35 pF. Compared to the DMOS parts, that's the moral equivalent of zero. What frequency are you working around?
> >This is a very fast switching app where slopes and ringout behavior matter. > >>> >>>> The datasheets aren't bad, for an RF phemt. There are actual DC >>>> curves! >>>> >>>> We use them as fast switches, and I took a bunch of data - >>>> capacitances, Ron at various biases, tempco, extended DC curves - and >>>> I'll email you what I have. Some of my data is for NE3508, same thing >>>> but twice as big. No Spice model. >>>> >>>> They appear to behave like jfets, in that you can ground the source >>>> and have the drain swing negative so long as you keep the gate >>>> suitably negative. >>>> >>>> They also enhance to many times the zero-gate-voltage conductance, >>>> numbers like 4 and 2 ohms Rds-on for the respective parts. >>>> >>> That sounds like a white knuckle ride :-) >> >> No, just bias the gate a few tenth of a volt positive. Works great. >> > >Ok, I'd dare to go to 300mV. But any closer is scary.
They won't conduct much gate current below 0.6 or so. I didn't test them past 0.3 because I wanted to drive the gate from ECL, 0.8 volts swing, and I needed about -0.5 or so to turn them off. But +0.5 would be fine, and the drain resistance should go down even more. PHEMTS seem to have a weird mode where drain current goes way up as you start to forward-bias the gate, almost as if it's starting to behave like a bipolar. I noticed this once but haven't had time to explore the effect. John
On Tue, 06 Sep 2011 17:53:22 -0700, Joerg <invalid@invalid.invalid>
wrote:

>John Larkin wrote: >> On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >>>> wrote: >>>> >>>>> Gents, >>>>> >>>>> Does anyone know where to find the SPICE model for the NE3509? Or at >>>>> least one that's close enough for pulse stuff? CEL only has the usual >>>>> microwave models but I want to use it as a fast low capacitance switch >>>>> and simulate in LTSpice. >>>> Have you asked NEC/CEL? >>>> >>> I haven't. Was in a rush and have plopped down a Calogic DS-series part >>> because I know it can do the job in this case. But I'd like to be able >>> to use the NE3509 in the future or in case things need to be even faster. >> >> Do you need a Spice model? As switches, these things are pretty >> simple. >> > >Yes, I do need a model. Reason is that things like Cgd versus channel >resistance matter. I was in a hurry so used Calogic parts now, good >enough for this application. There is a 2nd source (well, sorta) and >there is a SPICE model. > >This is a very fast switching app where slopes and ringout behavior matter. > >>> >>>> The datasheets aren't bad, for an RF phemt. There are actual DC >>>> curves! >>>> >>>> We use them as fast switches, and I took a bunch of data - >>>> capacitances, Ron at various biases, tempco, extended DC curves - and >>>> I'll email you what I have. Some of my data is for NE3508, same thing >>>> but twice as big. No Spice model. >>>> >>>> They appear to behave like jfets, in that you can ground the source >>>> and have the drain swing negative so long as you keep the gate >>>> suitably negative. >>>> >>>> They also enhance to many times the zero-gate-voltage conductance, >>>> numbers like 4 and 2 ohms Rds-on for the respective parts. >>>> >>> That sounds like a white knuckle ride :-) >> >> No, just bias the gate a few tenth of a volt positive. Works great. >> > >Ok, I'd dare to go to 300mV. But any closer is scary.
One other thought: a BFT25 makes an interesting RF switch. It's easier to use in shunt mode, with the emitter grounded, of course. They are a fraction of the price of PHEMT or DMOS discretes. I have data! John
John Larkin wrote:
> On Tue, 06 Sep 2011 17:53:22 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >>>>> wrote: >>>>> >>>>>> Gents, >>>>>> >>>>>> Does anyone know where to find the SPICE model for the NE3509? Or at >>>>>> least one that's close enough for pulse stuff? CEL only has the usual >>>>>> microwave models but I want to use it as a fast low capacitance switch >>>>>> and simulate in LTSpice. >>>>> Have you asked NEC/CEL? >>>>> >>>> I haven't. Was in a rush and have plopped down a Calogic DS-series part >>>> because I know it can do the job in this case. But I'd like to be able >>>> to use the NE3509 in the future or in case things need to be even faster. >>> Do you need a Spice model? As switches, these things are pretty >>> simple. >>> >> Yes, I do need a model. Reason is that things like Cgd versus channel >> resistance matter. I was in a hurry so used Calogic parts now, good >> enough for this application. There is a 2nd source (well, sorta) and >> there is a SPICE model. > > The 3509 has a drain capacitance, mostly to the source, that's fairly > constant at about 0.35 pF. Compared to the DMOS parts, that's the > moral equivalent of zero. >
Don't diss the old DMOS parts, their capacitances are also very low. Ok, not quite 0.35pF and the Rdson is tens of Ohms. But it was good enough in this case and, most importantly, there was a SPICE model.
> What frequency are you working around? >
Roughly between 0.5 and 1GHz.
>> This is a very fast switching app where slopes and ringout behavior matter. >> >>>>> The datasheets aren't bad, for an RF phemt. There are actual DC >>>>> curves! >>>>> >>>>> We use them as fast switches, and I took a bunch of data - >>>>> capacitances, Ron at various biases, tempco, extended DC curves - and >>>>> I'll email you what I have. Some of my data is for NE3508, same thing >>>>> but twice as big. No Spice model. >>>>> >>>>> They appear to behave like jfets, in that you can ground the source >>>>> and have the drain swing negative so long as you keep the gate >>>>> suitably negative. >>>>> >>>>> They also enhance to many times the zero-gate-voltage conductance, >>>>> numbers like 4 and 2 ohms Rds-on for the respective parts. >>>>> >>>> That sounds like a white knuckle ride :-) >>> No, just bias the gate a few tenth of a volt positive. Works great. >>> >> Ok, I'd dare to go to 300mV. But any closer is scary. > > They won't conduct much gate current below 0.6 or so. I didn't test > them past 0.3 because I wanted to drive the gate from ECL, 0.8 volts > swing, and I needed about -0.5 or so to turn them off. But +0.5 would > be fine, and the drain resistance should go down even more. > > PHEMTS seem to have a weird mode where drain current goes way up as > you start to forward-bias the gate, almost as if it's starting to > behave like a bipolar. I noticed this once but haven't had time to > explore the effect. >
That would be interesting to explore. Can't you do a contest for students like you did before? They could find out for you. And get an honorable mention in your patent application :-) -- Regards, Joerg http://www.analogconsultants.com/
John Larkin wrote:
> On Tue, 06 Sep 2011 17:53:22 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >>>>> wrote: >>>>> >>>>>> Gents, >>>>>> >>>>>> Does anyone know where to find the SPICE model for the NE3509? Or at >>>>>> least one that's close enough for pulse stuff? CEL only has the usual >>>>>> microwave models but I want to use it as a fast low capacitance switch >>>>>> and simulate in LTSpice. >>>>> Have you asked NEC/CEL? >>>>> >>>> I haven't. Was in a rush and have plopped down a Calogic DS-series part >>>> because I know it can do the job in this case. But I'd like to be able >>>> to use the NE3509 in the future or in case things need to be even faster. >>> Do you need a Spice model? As switches, these things are pretty >>> simple. >>> >> Yes, I do need a model. Reason is that things like Cgd versus channel >> resistance matter. I was in a hurry so used Calogic parts now, good >> enough for this application. There is a 2nd source (well, sorta) and >> there is a SPICE model. >> >> This is a very fast switching app where slopes and ringout behavior matter. >> >>>>> The datasheets aren't bad, for an RF phemt. There are actual DC >>>>> curves! >>>>> >>>>> We use them as fast switches, and I took a bunch of data - >>>>> capacitances, Ron at various biases, tempco, extended DC curves - and >>>>> I'll email you what I have. Some of my data is for NE3508, same thing >>>>> but twice as big. No Spice model. >>>>> >>>>> They appear to behave like jfets, in that you can ground the source >>>>> and have the drain swing negative so long as you keep the gate >>>>> suitably negative. >>>>> >>>>> They also enhance to many times the zero-gate-voltage conductance, >>>>> numbers like 4 and 2 ohms Rds-on for the respective parts. >>>>> >>>> That sounds like a white knuckle ride :-) >>> No, just bias the gate a few tenth of a volt positive. Works great. >>> >> Ok, I'd dare to go to 300mV. But any closer is scary. > > One other thought: a BFT25 makes an interesting RF switch. It's easier > to use in shunt mode, with the emitter grounded, of course. They are a > fraction of the price of PHEMT or DMOS discretes. > > I have data! >
Just one problem in my case: I found that even hotshot RF transistors take a noticeable time to get back out of even a slightly saturated condition. Nanoseconds, but still. The other issue is that you can't get them to zip Vce to zero like a FET can with Vds. That is required in most of my cases because of a DC component that must not be disturbed. -- Regards, Joerg http://www.analogconsultants.com/
On Wed, 07 Sep 2011 11:21:34 -0700, Joerg <invalid@invalid.invalid>
wrote:

>John Larkin wrote: >> On Tue, 06 Sep 2011 17:53:22 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Tue, 06 Sep 2011 13:59:38 -0700, Joerg <invalid@invalid.invalid> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>>> On Tue, 06 Sep 2011 12:16:12 -0700, Joerg <invalid@invalid.invalid> >>>>>> wrote: >>>>>> >>>>>>> Gents, >>>>>>> >>>>>>> Does anyone know where to find the SPICE model for the NE3509? Or at >>>>>>> least one that's close enough for pulse stuff? CEL only has the usual >>>>>>> microwave models but I want to use it as a fast low capacitance switch >>>>>>> and simulate in LTSpice. >>>>>> Have you asked NEC/CEL? >>>>>> >>>>> I haven't. Was in a rush and have plopped down a Calogic DS-series part >>>>> because I know it can do the job in this case. But I'd like to be able >>>>> to use the NE3509 in the future or in case things need to be even faster. >>>> Do you need a Spice model? As switches, these things are pretty >>>> simple. >>>> >>> Yes, I do need a model. Reason is that things like Cgd versus channel >>> resistance matter. I was in a hurry so used Calogic parts now, good >>> enough for this application. There is a 2nd source (well, sorta) and >>> there is a SPICE model. >> >> The 3509 has a drain capacitance, mostly to the source, that's fairly >> constant at about 0.35 pF. Compared to the DMOS parts, that's the >> moral equivalent of zero. >> > >Don't diss the old DMOS parts, their capacitances are also very low. Ok, >not quite 0.35pF and the Rdson is tens of Ohms. But it was good enough >in this case and, most importantly, there was a SPICE model. > > >> What frequency are you working around? >> > >Roughly between 0.5 and 1GHz. > > >>> This is a very fast switching app where slopes and ringout behavior matter. >>> >>>>>> The datasheets aren't bad, for an RF phemt. There are actual DC >>>>>> curves! >>>>>> >>>>>> We use them as fast switches, and I took a bunch of data - >>>>>> capacitances, Ron at various biases, tempco, extended DC curves - and >>>>>> I'll email you what I have. Some of my data is for NE3508, same thing >>>>>> but twice as big. No Spice model. >>>>>> >>>>>> They appear to behave like jfets, in that you can ground the source >>>>>> and have the drain swing negative so long as you keep the gate >>>>>> suitably negative. >>>>>> >>>>>> They also enhance to many times the zero-gate-voltage conductance, >>>>>> numbers like 4 and 2 ohms Rds-on for the respective parts. >>>>>> >>>>> That sounds like a white knuckle ride :-) >>>> No, just bias the gate a few tenth of a volt positive. Works great. >>>> >>> Ok, I'd dare to go to 300mV. But any closer is scary. >> >> They won't conduct much gate current below 0.6 or so. I didn't test >> them past 0.3 because I wanted to drive the gate from ECL, 0.8 volts >> swing, and I needed about -0.5 or so to turn them off. But +0.5 would >> be fine, and the drain resistance should go down even more. >> >> PHEMTS seem to have a weird mode where drain current goes way up as >> you start to forward-bias the gate, almost as if it's starting to >> behave like a bipolar. I noticed this once but haven't had time to >> explore the effect. >> > >That would be interesting to explore. Can't you do a contest for >students like you did before? They could find out for you. And get an >honorable mention in your patent application :-)
It would be cool to have someone who could occasionally do some parts testing, or Spicing, or parts research, or breadboard circuit testing, for interesting ideas that we don't have time for. But if I did that, I wouldn't get to solder any more at all. I'd need a new PHB hairdoo. John