ECL logic SPICE models
in [Design]
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From: Tim Williams on 12 Sep 2009 01:05 On Sep 11, 9:05 pm, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > Lots of RF devices seem to have voltage ratings that assume an RF tank > in the output, so that the actual instantaneous drain excursion is 0 > to twice Vcc. Really? I thought that went away with vacuum tubes! 6V6GT is rated for 315V Maximum (Design Center Value), but 1200V Absolute Maximum (in triode mode, in fact). The latter is the peak value! Tim
From: Joerg on 12 Sep 2009 11:51 John Larkin wrote: > On Fri, 11 Sep 2009 16:38:42 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Fri, 11 Sep 2009 15:33:08 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: [...] >> >>>> One issue I found with RF devices was that you can sometimes only obtain >>>> small signal simulator models that aren't very helpful with pulse apps, >>>> plus require software that costs more than your Volkswagen. Even with >>>> big LDMOS parts I had that happen. One company (PolyFet) stuck out and >>>> provided SPICE models. So the big competitor will be left out ... sorry, >>>> NXP. >>> I don't simulate this stuff, I test. Most microwave parts are >>> characterized small-signal, S-params. Spice models are very rare in >>> this business. I know things about some of these parts that the >>> manufacturers don't know. >>> >> Lately I have simulated more, and then straight to layout. The one >> that's in fab right now is a white-knuckle ride because I am using a >> device in a weird way. Usually pans out though. >> >> What often amazes me is how close to abs max people (and sometimes app >> notes) bias RF devices. When it says 7V they bias them to 5V or 6V on >> the collector/drain. Some day a huge pulse finds its way into the input, >> almost saturates the device, then it lets go, the inductor shoots up ... >> phut. > > I've run 7-volt-rated MESfets at 18 volts, and 2 volt RF schottkies at > 6. I sometimes test parts to destruction and then back off some. The > performance is often worth the small risk. > I've seen that. But if you are a consultant and this goes into some aircraft you can't design like that. Even with an indemnification clause that can cause lots of grief should it go wrong in only one case. It's got to be by the book. > Lots of RF devices seem to have voltage ratings that assume an RF tank > in the output, so that the actual instantaneous drain excursion is 0 > to twice Vcc. The RF guys are really, really terrible when it comes to > realtime specs. You're lucky to get any DC curves. More often there's > an app circuit with an input match, an output match, and a gate bias > trimpot. > All they really offer in many cases is a set of S-parameters. Since I design a lot of pulse circuitry I almost do a rain dance every time there is just a snippet of SPICE data. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 12 Sep 2009 13:01 On Sat, 12 Sep 2009 08:51:21 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Fri, 11 Sep 2009 16:38:42 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Fri, 11 Sep 2009 15:33:08 -0700, Joerg <invalid(a)invalid.invalid> >>>> wrote: > >[...] > >>> >>>>> One issue I found with RF devices was that you can sometimes only obtain >>>>> small signal simulator models that aren't very helpful with pulse apps, >>>>> plus require software that costs more than your Volkswagen. Even with >>>>> big LDMOS parts I had that happen. One company (PolyFet) stuck out and >>>>> provided SPICE models. So the big competitor will be left out ... sorry, >>>>> NXP. >>>> I don't simulate this stuff, I test. Most microwave parts are >>>> characterized small-signal, S-params. Spice models are very rare in >>>> this business. I know things about some of these parts that the >>>> manufacturers don't know. >>>> >>> Lately I have simulated more, and then straight to layout. The one >>> that's in fab right now is a white-knuckle ride because I am using a >>> device in a weird way. Usually pans out though. >>> >>> What often amazes me is how close to abs max people (and sometimes app >>> notes) bias RF devices. When it says 7V they bias them to 5V or 6V on >>> the collector/drain. Some day a huge pulse finds its way into the input, >>> almost saturates the device, then it lets go, the inductor shoots up ... >>> phut. >> >> I've run 7-volt-rated MESfets at 18 volts, and 2 volt RF schottkies at >> 6. I sometimes test parts to destruction and then back off some. The >> performance is often worth the small risk. >> > >I've seen that. But if you are a consultant and this goes into some >aircraft you can't design like that. Even with an indemnification clause >that can cause lots of grief should it go wrong in only one case. It's >got to be by the book. > > >> Lots of RF devices seem to have voltage ratings that assume an RF tank >> in the output, so that the actual instantaneous drain excursion is 0 >> to twice Vcc. The RF guys are really, really terrible when it comes to >> realtime specs. You're lucky to get any DC curves. More often there's >> an app circuit with an input match, an output match, and a gate bias >> trimpot. >> > >All they really offer in many cases is a set of S-parameters. Since I >design a lot of pulse circuitry I almost do a rain dance every time >there is just a snippet of SPICE data. Somewhere in my bag-o-tricks is an S-Parameter-to-Spice-Model converter (and vice-versa). When I find it I'll post. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Jim Thompson on 12 Sep 2009 14:08 On Sat, 12 Sep 2009 10:01:22 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Sat, 12 Sep 2009 08:51:21 -0700, Joerg <invalid(a)invalid.invalid> >wrote: > >>John Larkin wrote: >>> On Fri, 11 Sep 2009 16:38:42 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Fri, 11 Sep 2009 15:33:08 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >> >>[...] >> >>>> >>>>>> One issue I found with RF devices was that you can sometimes only obtain >>>>>> small signal simulator models that aren't very helpful with pulse apps, >>>>>> plus require software that costs more than your Volkswagen. Even with >>>>>> big LDMOS parts I had that happen. One company (PolyFet) stuck out and >>>>>> provided SPICE models. So the big competitor will be left out ... sorry, >>>>>> NXP. >>>>> I don't simulate this stuff, I test. Most microwave parts are >>>>> characterized small-signal, S-params. Spice models are very rare in >>>>> this business. I know things about some of these parts that the >>>>> manufacturers don't know. >>>>> >>>> Lately I have simulated more, and then straight to layout. The one >>>> that's in fab right now is a white-knuckle ride because I am using a >>>> device in a weird way. Usually pans out though. >>>> >>>> What often amazes me is how close to abs max people (and sometimes app >>>> notes) bias RF devices. When it says 7V they bias them to 5V or 6V on >>>> the collector/drain. Some day a huge pulse finds its way into the input, >>>> almost saturates the device, then it lets go, the inductor shoots up ... >>>> phut. >>> >>> I've run 7-volt-rated MESfets at 18 volts, and 2 volt RF schottkies at >>> 6. I sometimes test parts to destruction and then back off some. The >>> performance is often worth the small risk. >>> >> >>I've seen that. But if you are a consultant and this goes into some >>aircraft you can't design like that. Even with an indemnification clause >>that can cause lots of grief should it go wrong in only one case. It's >>got to be by the book. >> >> >>> Lots of RF devices seem to have voltage ratings that assume an RF tank >>> in the output, so that the actual instantaneous drain excursion is 0 >>> to twice Vcc. The RF guys are really, really terrible when it comes to >>> realtime specs. You're lucky to get any DC curves. More often there's >>> an app circuit with an input match, an output match, and a gate bias >>> trimpot. >>> >> >>All they really offer in many cases is a set of S-parameters. Since I >>design a lot of pulse circuitry I almost do a rain dance every time >>there is just a snippet of SPICE data. > >Somewhere in my bag-o-tricks is an S-Parameter-to-Spice-Model >converter (and vice-versa). > >When I find it I'll post. > > ...Jim Thompson All my S-Parameter to Spice stuff has been updated on the SED page of my website... except a good article by Microcap... get that from their website, so I don't step on any copyright toes ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Joerg on 12 Sep 2009 14:15
Jim Thompson wrote: > On Sat, 12 Sep 2009 08:51:21 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Fri, 11 Sep 2009 16:38:42 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Fri, 11 Sep 2009 15:33:08 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >> [...] >> >>>>>> One issue I found with RF devices was that you can sometimes only obtain >>>>>> small signal simulator models that aren't very helpful with pulse apps, >>>>>> plus require software that costs more than your Volkswagen. Even with >>>>>> big LDMOS parts I had that happen. One company (PolyFet) stuck out and >>>>>> provided SPICE models. So the big competitor will be left out ... sorry, >>>>>> NXP. >>>>> I don't simulate this stuff, I test. Most microwave parts are >>>>> characterized small-signal, S-params. Spice models are very rare in >>>>> this business. I know things about some of these parts that the >>>>> manufacturers don't know. >>>>> >>>> Lately I have simulated more, and then straight to layout. The one >>>> that's in fab right now is a white-knuckle ride because I am using a >>>> device in a weird way. Usually pans out though. >>>> >>>> What often amazes me is how close to abs max people (and sometimes app >>>> notes) bias RF devices. When it says 7V they bias them to 5V or 6V on >>>> the collector/drain. Some day a huge pulse finds its way into the input, >>>> almost saturates the device, then it lets go, the inductor shoots up ... >>>> phut. >>> I've run 7-volt-rated MESfets at 18 volts, and 2 volt RF schottkies at >>> 6. I sometimes test parts to destruction and then back off some. The >>> performance is often worth the small risk. >>> >> I've seen that. But if you are a consultant and this goes into some >> aircraft you can't design like that. Even with an indemnification clause >> that can cause lots of grief should it go wrong in only one case. It's >> got to be by the book. >> >> >>> Lots of RF devices seem to have voltage ratings that assume an RF tank >>> in the output, so that the actual instantaneous drain excursion is 0 >>> to twice Vcc. The RF guys are really, really terrible when it comes to >>> realtime specs. You're lucky to get any DC curves. More often there's >>> an app circuit with an input match, an output match, and a gate bias >>> trimpot. >>> >> All they really offer in many cases is a set of S-parameters. Since I >> design a lot of pulse circuitry I almost do a rain dance every time >> there is just a snippet of SPICE data. > > Somewhere in my bag-o-tricks is an S-Parameter-to-Spice-Model > converter (and vice-versa). > > When I find it I'll post. > That would be very kind. However, except for super large transmitter devices (and sometimes even then) the S-parameters have been measured under small signal conditions. Doesn't help much when pulsing them hard, then you are back to what John said, experiments on the lab bench. Got one of those coming up. I am going to do the first run with tubes again to see if the concept pans out, in order not to have stuff blow up in my face. It's really nice to know that one can still buy the mil version of the 6146 tube, at affordable prices. So far I haven't blown one though, only tired out a pair. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |