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SPICE gets it wrong

Started by Tim Williams May 7, 2017
On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje
<pNa0nStpealmtje@yahoo.com> wrote:

>On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin ><jjlarkin@highland_snip_technology.com> wrote in ><qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: > >>I rarely use bipolar transistors any more. > >Maybe for high end stuff like you are making, >but for many down to earth things they are very useful, >bipolars are basically current amplifiers. >MOSFETS voltage to current converters. >Both have their field of application where they are best. >And there are some nice RF ones too.
We trend to use PHEMTS for fast stuff. The place where we use still bipolars is in positive current sources, because mosfets have too much capacitance and nobody makes p-channel phemts. Base current sucks. I designed a fast currrent source with base current correction, but it's kinda complex. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On 05/10/2017 10:56 AM, John Larkin wrote:
> On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje > <pNa0nStpealmtje@yahoo.com> wrote: > >> On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin >> <jjlarkin@highland_snip_technology.com> wrote in >> <qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: >> >>> I rarely use bipolar transistors any more. >> >> Maybe for high end stuff like you are making, >> but for many down to earth things they are very useful, >> bipolars are basically current amplifiers. >> MOSFETS voltage to current converters. >> Both have their field of application where they are best. >> And there are some nice RF ones too. > > We trend to use PHEMTS for fast stuff. The place where we use still > bipolars is in positive current sources, because mosfets have too much > capacitance and nobody makes p-channel phemts. > > Base current sucks. I designed a fast currrent source with base > current correction, but it's kinda complex.
I mostly use BJTs as transconductance devices, and their nice repeatable turn-on is a big plus. They're also much better in low-voltage analogue stuff for the same reason. Besides being much, much quieter. PNPs are good for positive-to-negative level shifting, too. Those SiGe:C devices (BFP640/650) are magic--high beta, low noise, effectively infinite VAF, and bandwidth that goes on forever. As you pointed out some time back, they don't switch as fast as pHEMTs that are seemingly slower. That one-diode sampler I did with ChesterW last year originally used a BFP640FESD, which produced a 200-ps sampler. Swapping it out for an ATF55143 got us down to 100 ps, but cost an extra 45 cents ($0.67 vs $0.22). Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On 05/10/2017 10:42 AM, Jan Panteltje wrote:

>>> I exected a circuit diagram ;-( >> >> Sorry, that's too valuable to give away. I will say: drive the gates >> hard and ignore the data sheets. > > Let me guess, you used an ethernet transformer...?
Nah nah it was an _isdn_ xfrmr. That's the good shit
> > Maybe some science field, was just reading CERN started a new linear accellerator: > https://home.cern/about/updates/2017/05/brand-new-linear-accelerator-cern >
Where's Famous Chef Pante?
On Wed, 10 May 2017 11:30:14 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:

>On 05/10/2017 10:42 AM, Jan Panteltje wrote: > >>>> I exected a circuit diagram ;-( >>> >>> Sorry, that's too valuable to give away. I will say: drive the gates >>> hard and ignore the data sheets. >> >> Let me guess, you used an ethernet transformer...? > >Nah nah it was an _isdn_ xfrmr. That's the good shit
ISDN transformers are really cool; I've used lots of them (over 20K!) in power supplies and such. My favorite part is 1:1:2:2, which is pretty versatile. But I use home-made transmission-line xfmrs for big fast pulses. Is ISDN still alive? "It Still Does Nothing" -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Wed, 10 May 2017 11:20:19 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 05/10/2017 10:56 AM, John Larkin wrote: >> On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje >> <pNa0nStpealmtje@yahoo.com> wrote: >> >>> On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin >>> <jjlarkin@highland_snip_technology.com> wrote in >>> <qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: >>> >>>> I rarely use bipolar transistors any more. >>> >>> Maybe for high end stuff like you are making, >>> but for many down to earth things they are very useful, >>> bipolars are basically current amplifiers. >>> MOSFETS voltage to current converters. >>> Both have their field of application where they are best. >>> And there are some nice RF ones too. >> >> We trend to use PHEMTS for fast stuff. The place where we use still >> bipolars is in positive current sources, because mosfets have too much >> capacitance and nobody makes p-channel phemts. >> >> Base current sucks. I designed a fast currrent source with base >> current correction, but it's kinda complex. > >I mostly use BJTs as transconductance devices, and their nice repeatable >turn-on is a big plus. They're also much better in low-voltage analogue >stuff for the same reason. Besides being much, much quieter. > >PNPs are good for positive-to-negative level shifting, too. > >Those SiGe:C devices (BFP640/650) are magic--high beta, low noise, >effectively infinite VAF, and bandwidth that goes on forever. As you >pointed out some time back, they don't switch as fast as pHEMTs that are >seemingly slower. That one-diode sampler I did with ChesterW last year >originally used a BFP640FESD, which produced a 200-ps sampler. Swapping >it out for an ATF55143 got us down to 100 ps, but cost an extra 45 cents >($0.67 vs $0.22). > >Cheers > >Phil Hobbs
The problem with fast bipolars, especially PNPs, is that they keep getting EOL'd. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 05/10/2017 12:27 PM, John Larkin wrote:
> On Wed, 10 May 2017 11:20:19 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 05/10/2017 10:56 AM, John Larkin wrote: >>> On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje >>> <pNa0nStpealmtje@yahoo.com> wrote: >>> >>>> On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin >>>> <jjlarkin@highland_snip_technology.com> wrote in >>>> <qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: >>>> >>>>> I rarely use bipolar transistors any more. >>>> >>>> Maybe for high end stuff like you are making, >>>> but for many down to earth things they are very useful, >>>> bipolars are basically current amplifiers. >>>> MOSFETS voltage to current converters. >>>> Both have their field of application where they are best. >>>> And there are some nice RF ones too. >>> >>> We trend to use PHEMTS for fast stuff. The place where we use still >>> bipolars is in positive current sources, because mosfets have too much >>> capacitance and nobody makes p-channel phemts. >>> >>> Base current sucks. I designed a fast currrent source with base >>> current correction, but it's kinda complex. >> >> I mostly use BJTs as transconductance devices, and their nice repeatable >> turn-on is a big plus. They're also much better in low-voltage analogue >> stuff for the same reason. Besides being much, much quieter. >> >> PNPs are good for positive-to-negative level shifting, too. >> >> Those SiGe:C devices (BFP640/650) are magic--high beta, low noise, >> effectively infinite VAF, and bandwidth that goes on forever. As you >> pointed out some time back, they don't switch as fast as pHEMTs that are >> seemingly slower. That one-diode sampler I did with ChesterW last year >> originally used a BFP640FESD, which produced a 200-ps sampler. Swapping >> it out for an ATF55143 got us down to 100 ps, but cost an extra 45 cents >> ($0.67 vs $0.22). >> >> Cheers >> >> Phil Hobbs > > The problem with fast bipolars, especially PNPs, is that they keep > getting EOL'd. > >
I'm planning to get a few reels for insurance pretty soon. BFP640s are too useful to lose, and they're only 20 cents or so--just like a BF862. A couple of dollar's worth of fancy transistors can let me build a very swoopy box that sells (hopefully!) for $2k-ish. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On Wed, 10 May 2017 12:37:04 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 05/10/2017 12:27 PM, John Larkin wrote: >> On Wed, 10 May 2017 11:20:19 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 05/10/2017 10:56 AM, John Larkin wrote: >>>> On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje >>>> <pNa0nStpealmtje@yahoo.com> wrote: >>>> >>>>> On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin >>>>> <jjlarkin@highland_snip_technology.com> wrote in >>>>> <qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: >>>>> >>>>>> I rarely use bipolar transistors any more. >>>>> >>>>> Maybe for high end stuff like you are making, >>>>> but for many down to earth things they are very useful, >>>>> bipolars are basically current amplifiers. >>>>> MOSFETS voltage to current converters. >>>>> Both have their field of application where they are best. >>>>> And there are some nice RF ones too. >>>> >>>> We trend to use PHEMTS for fast stuff. The place where we use still >>>> bipolars is in positive current sources, because mosfets have too much >>>> capacitance and nobody makes p-channel phemts. >>>> >>>> Base current sucks. I designed a fast currrent source with base >>>> current correction, but it's kinda complex. >>> >>> I mostly use BJTs as transconductance devices, and their nice repeatable >>> turn-on is a big plus. They're also much better in low-voltage analogue >>> stuff for the same reason. Besides being much, much quieter. >>> >>> PNPs are good for positive-to-negative level shifting, too. >>> >>> Those SiGe:C devices (BFP640/650) are magic--high beta, low noise, >>> effectively infinite VAF, and bandwidth that goes on forever. As you >>> pointed out some time back, they don't switch as fast as pHEMTs that are >>> seemingly slower. That one-diode sampler I did with ChesterW last year >>> originally used a BFP640FESD, which produced a 200-ps sampler. Swapping >>> it out for an ATF55143 got us down to 100 ps, but cost an extra 45 cents >>> ($0.67 vs $0.22). >>> >>> Cheers >>> >>> Phil Hobbs >> >> The problem with fast bipolars, especially PNPs, is that they keep >> getting EOL'd. >> >> > >I'm planning to get a few reels for insurance pretty soon. BFP640s are >too useful to lose, and they're only 20 cents or so--just like a BF862. > >A couple of dollar's worth of fancy transistors can let me build a very >swoopy box that sells (hopefully!) for $2k-ish. > >Cheers > >Phil Hobbs
We both sell IP, soldered to PC boards. One of our customers wants to audit our parts cost to see if we're making too much money. We declined. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 05/10/2017 12:11 PM, John Larkin wrote:
> On Wed, 10 May 2017 11:30:14 -0400, bitrex > <bitrex@de.lete.earthlink.net> wrote: > >> On 05/10/2017 10:42 AM, Jan Panteltje wrote: >> >>>>> I exected a circuit diagram ;-( >>>> >>>> Sorry, that's too valuable to give away. I will say: drive the gates >>>> hard and ignore the data sheets. >>> >>> Let me guess, you used an ethernet transformer...? >> >> Nah nah it was an _isdn_ xfrmr. That's the good shit > > ISDN transformers are really cool; I've used lots of them (over 20K!) > in power supplies and such. My favorite part is 1:1:2:2, which is > pretty versatile. But I use home-made transmission-line xfmrs for big > fast pulses. > > Is ISDN still alive? "It Still Does Nothing"
I know it was "Big in Japan" for a while... <https://www.youtube.com/watch?v=DdWZKb659K0> I think it's still used by some businesses for POS applications and stuff. The wiki says Verizon no longer offers it in the Northeast as of 2013
On 05/10/2017 10:56 AM, John Larkin wrote:
> On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje > <pNa0nStpealmtje@yahoo.com> wrote: > >> On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin >> <jjlarkin@highland_snip_technology.com> wrote in >> <qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: >> >>> I rarely use bipolar transistors any more. >> >> Maybe for high end stuff like you are making, >> but for many down to earth things they are very useful, >> bipolars are basically current amplifiers. >> MOSFETS voltage to current converters. >> Both have their field of application where they are best. >> And there are some nice RF ones too. > > We trend to use PHEMTS for fast stuff. The place where we use still > bipolars is in positive current sources, because mosfets have too much > capacitance and nobody makes p-channel phemts. > > Base current sucks. I designed a fast currrent source with base > current correction, but it's kinda complex. >
BJTs are really more like voltage controlled current sources with a pathology than current controlled current sources
On Wed, 10 May 2017 16:16:56 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:

>On 05/10/2017 10:56 AM, John Larkin wrote: >> On Wed, 10 May 2017 08:05:51 GMT, Jan Panteltje >> <pNa0nStpealmtje@yahoo.com> wrote: >> >>> On a sunny day (Tue, 09 May 2017 16:32:11 -0700) it happened John Larkin >>> <jjlarkin@highland_snip_technology.com> wrote in >>> <qak4hc5lre1ohrf47f734bvk2qqvfl634b@4ax.com>: >>> >>>> I rarely use bipolar transistors any more. >>> >>> Maybe for high end stuff like you are making, >>> but for many down to earth things they are very useful, >>> bipolars are basically current amplifiers. >>> MOSFETS voltage to current converters. >>> Both have their field of application where they are best. >>> And there are some nice RF ones too. >> >> We trend to use PHEMTS for fast stuff. The place where we use still >> bipolars is in positive current sources, because mosfets have too much >> capacitance and nobody makes p-channel phemts. >> >> Base current sucks. I designed a fast currrent source with base >> current correction, but it's kinda complex. >> > >BJTs are really more like voltage controlled current sources with a >pathology than current controlled current sources
Bwahahahahahaha >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Thinking outside the box... producing elegant solutions. "It is not in doing what you like, but in liking what you do that is the secret of happiness." -James Barrie