On Mon, 27 Aug 2012 12:42:32 -0400, "Tom Del Rosso" <td_03@verizon.net.invalid> wrote:> >John Larkin wrote: >> On Sun, 26 Aug 2012 22:53:35 -0400, "Tom Del Rosso" >> <td_03@verizon.net.invalid> wrote: >> >> > >> > John Larkin wrote: >> > > >> > > You *don't* understand my circuit! >> > >> > I wish I did. Whether he does or not, would you mind describing it? >> >> This one? >> >> https://dl.dropbox.com/u/53724080/Circuits/Isrc_Ib_2.JPG >> >> U1 and the p-fet are a slow but precise closed-loop current source. >> It's cascoded into the fast PNP transistor below, which gives us low >> output capacitance. R3 allows the PNP emitter to move a bit and reduce >> Early effect. R4 keeps the PNP from oscillating. >> >> The big DC error becomes the base current of the PNP. RF PNPs tend to >> have have low betas, so we lose some of our precise current to the >> base, and that changes with tempearture. So we dump the base current >> into U2, and the resulting signal (drop across R2) increases the >> effective reference voltage to the upper current source, increasing >> the emitter current, almost canceling the base current error. >> >> R2=R1 gets us close enough. The base current cancellation is a >> positive feedback loop, but the gain is low, basically 1/beta, so it's >> stable. >> >> Jim is on record as not liking this. He won't say why.It's only _claimed_ stable, not proven. It obviously doesn't meet your linearity requirement.> >It's very interesting, especially using the base that way. Ten years ago it >would have been the subject of an interesting discussion on SED. > >I'm constantly reminded of an argument and a falling out that occurred when >I was 11. The bystanders here even take sides more than they did then. I >specifically said the 'pimp' comment was over the line but haven't taken >sides other than that.It occurred precisely _once_. Can you cite the message ID? I can :-) Larkin doesn't want to drop the issue... he'd have nothing left to assault me with. ...Jim Thompson -- | James E.Thompson, CTO | 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.
pc motherboard grounds
Started by ●August 25, 2012
Reply by ●August 27, 20122012-08-27
Reply by ●August 27, 20122012-08-27
Tom Del Rosso wrote:> > John Larkin wrote: > > On Sun, 26 Aug 2012 22:53:35 -0400, "Tom Del Rosso" > > <td_03@verizon.net.invalid> wrote: > > > > > > > > John Larkin wrote: > > > > > > > > You *don't* understand my circuit! > > > > > > I wish I did. Whether he does or not, would you mind describing it? > > > > This one? > > > > https://dl.dropbox.com/u/53724080/Circuits/Isrc_Ib_2.JPG > > > > U1 and the p-fet are a slow but precise closed-loop current source. > > It's cascoded into the fast PNP transistor below, which gives us low > > output capacitance. R3 allows the PNP emitter to move a bit and reduce > > Early effect. R4 keeps the PNP from oscillating. > > > > The big DC error becomes the base current of the PNP. RF PNPs tend to > > have have low betas, so we lose some of our precise current to the > > base, and that changes with tempearture. So we dump the base current > > into U2, and the resulting signal (drop across R2) increases the > > effective reference voltage to the upper current source, increasing > > the emitter current, almost canceling the base current error. > > > > R2=R1 gets us close enough. The base current cancellation is a > > positive feedback loop, but the gain is low, basically 1/beta, so it's > > stable. > >The problem I see with that is that the base current correction only works at DC. For few-percent error tolerance, it's probably fine, but the step response will have whoop-de-doos. (They may be too far out in time to care about, but they could also interact with subsequent pulses and cause jitter.) I still say that simulated inductor circuit is simpler--4 parts, zero current error at all frequencies, L as high as you like (if you use a BFP640). You can put a damping resistor in parallel to kill the Q if that's an issue. (I suppose the whoop-de-do jitter issue might be there as well, somewhere between the bandwidths of the LC and the op amp loop, but I'd have to think way too hard to figure that out.) ;) 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 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 09:57:29 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Mon, 27 Aug 2012 09:14:28 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Mon, 27 Aug 2012 09:01:25 -0700, SoothSayer >><SaySooth@TheMonastery.org> wrote: >> >>>On Mon, 27 Aug 2012 08:46:14 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>You can't pick values that would make this circuit work, because you >>>>can't understand it. Spice does all your thinking for you. >>> >>> >>> The sad thing is that you cannot possibly believe that about him, but >>>you do. >> >>It would be easy for him to prove otherwise. >> >>I do in fact believe it of him. If he can't Spice it, he can't >>evaluate it. > >It's build it or Spice it to PROVE it. > >I DESIGN more circuits per year than Larkin can even count that high. > >Like Joerg, I can't publish my work, it's all proprietary. That's why >I say "Come by". You can look over my shoulder, but no print-outs (or >cameras :-) > >Larkin throws up (literally) his problems on this page, but never >shows the final solution (probably because he stole the solution from >one of responding posters).I've posted a number of PDFs of actual schematics in actual production products. *I* decide what's proprietary. I also post circuit ideas to play with, some serious and some goofy, but you never play. Playing with circuits is a fun sport, like riffing on a jazz theme, but you can't do it.> >Larkin is indeed a Napoleonic runt. > > ...Jim ThompsonYou never talk about electronics any more. You just whine about personalities. What an old hen. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by ●August 27, 20122012-08-27
Jim Thompson wrote:> > It occurred precisely _once_. Can you cite the message ID? I can :-)I don't see why once isn't enough to warrant an apology, but everything since then consists of mutual accusations of incompetence that are nonsense. -- Reply in group, but if emailing add one more zero, and remove the last word.
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 10:19:39 -0700, John Larkin <jlarkin@highlandtechnology.com> wrote:>On Mon, 27 Aug 2012 09:57:29 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >[snip]>> >>Larkin is indeed a Napoleonic runt. >> >> ...Jim Thompson > > >You never talk about electronics any more. You just whine about >personalities. What an old hen.And you're too ignorant to understand what's funny about your last statement ;-) ...Jim Thompson -- | James E.Thompson, CTO | 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.
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 13:20:22 -0400, "Tom Del Rosso" <td_03@verizon.net.invalid> wrote:> >Jim Thompson wrote: >> >> It occurred precisely _once_. Can you cite the message ID? I can :-) > >I don't see why once isn't enough to warrant an apology,I offered an apology. It was refused.>but everything >since then consists of mutual accusations of incompetence that are nonsense.Of course, though any rational person would question Larkin's competence... he NEVER posts EXACT... he specializes in vagueness. ...Jim Thompson -- | James E.Thompson, CTO | 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.
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 08:26:50 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Mon, 27 Aug 2012 07:00:58 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Sun, 26 Aug 2012 21:43:00 -0700, josephkk >><joseph_barrett@sbcglobal.net> wrote: >> >>>On Sun, 26 Aug 2012 12:38:59 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Sun, 26 Aug 2012 08:01:35 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>>On Sat, 25 Aug 2012 21:58:02 -0700, John Larkin >>>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>>> >>>>>>On Sat, 25 Aug 2012 19:47:01 -0700, Jim Thompson >>>>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>>> >>>>>>>On Sat, 25 Aug 2012 18:19:02 -0700, John Larkin >>>>>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> >>>>>[snip] >>>>>>> >>>>>>>WHERE did you SHOW a WORKING circuit ?? You didn't. >>>>>> >>>>>>I've posted a bunch of current source circuits. They all work. >>>>> >>>>>In previous posts you said that the ones you attempted for your 1V/ns >>>>>ramp oscillated?? >>>> >>>>It depends on the PNP transistor and the value of the base resistor. A >>>>BCX71 oscillates at around 80 MHz, and the hotter RF parts much >>>>higher. It has nothing to do with the opamp gain/phase as you >>>>suggested; the oscillation is local to the transistor. 100 ohms in the >>>>base fixes it for pretty much all cases. >>>> >>>>> >>>>>> >>>>>>> >>>>>>>I design sub-nanosecond stuff on-chip all the time, so shove your >>>>>>>snarky crap up your ass. >>>>>>> >>>>>>>You're a shit "designer"... all NO-SHOW. >>>>>>> >>>>>>> ...Jim Thompson >>>>>> >>>>>>So show something of your own. >>>>>> >>>>>>You can't. >>>>> >>>>>Show us the ramp device that _doesn't_ oscillate. >>>> >>>>As noted, the proper base/gate resistor fixes it, as it does for most >>>>emitter-follower type circuits. Not many people appreciate how much >>>>emitter follower configs (low-z in the base, hi-z in the emitter) like >>>>to oscillate. >>> >>>Poxy hell, you point to your own lack of understanding. That is a totally >>>inappropriate use of an emitter follower. No wonder you have silly >>>problems, you don't grok electronics at all. >> >>It's not an emitter follower, but it is an "emitter-follower type >>circuit", namely the emitter does not see a low impedance to ground, >>but the base does. A base resistor is a good way to prevent VHF >>oscillations. This the the so-called "base stopper" or, or mosfet >>amps, "gate stopper" resistor in Olde English. >> >>Don't be a jerk. > >Anyone who disagrees with Larkin on a technical level receives ad >hominem designation as a jerk, old hen, senile, whatever.You don't disagree with me on a technical level, because you never say anything intelligent about circuits any more. Which is why your content-free whining makes you an old hen. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 10:22:46 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Mon, 27 Aug 2012 10:19:39 -0700, John Larkin ><jlarkin@highlandtechnology.com> wrote: > >>On Mon, 27 Aug 2012 09:57:29 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >[snip] >>> >>>Larkin is indeed a Napoleonic runt. >>> >>> ...Jim Thompson >> >> >>You never talk about electronics any more. You just whine about >>personalities. What an old hen. > >And you're too ignorant to understand what's funny about your last >statement ;-) > > ...Jim ThompsonSay something real about electronics. Design a current source, or say something real about the ones I've posted. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 09:12:23 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>Where? All you do is whine.Describing your fucked up personality is NOT "whining" you fucking immature bastard.
Reply by ●August 27, 20122012-08-27
On Mon, 27 Aug 2012 09:14:28 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>I do in fact believe it of him. If he can't Spice it, he can't >evaluate it. >You really are dumber than dogshit. When I said it in the past, it was just a poke in the ribs. That status has changed.
