On Sat, 18 Aug 2012 04:23:11 -0700 (PDT), Mr Stonebeach <reg@wmail.fi> wrote:>On Aug 18, 8:03�am, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> I hate to brag about how old I am, but Spice was introduced to the >> world in 1973 > > Interesting, that's roughly the same time as my favourite simulator >APLAC. I was under impression that SPICE would have been older. > > Regards, > MikkoAnd my PDP8, with 4K of 12-bit core and teletype i/o, couldn't have run anything like Spice anyhow. FOCAL was an amazing piece of software. I could edit and run my steamship simulation program, and plot transient responses sideways on the teletype, in that 4K. We made a presentation to the shipyard people and the owners. We'd never done a control system before. I was 19 and looked 15. I rolled out my transient graphs, hand colored over the teletype * and $ and # graph points, in front of a huge old grizzled ex-Chief ships engineer. He said "that's just the way an experienced seaman would work the valves manually" so we got the job. I used an analog nonlinear function generator to map throttle position to estimated steam valve position, and slew rate limited that into the steam valve position servo loop. A tach picked up shaft RPM and generated a limited-amplitude RPM error to sum into a P+I loop, so a bad tach wouldn't let the thing run away too far. That turned out to produce the transient responses the guy recognized. Mostly uA709s and diodes and stuff. The tiniest 8-bit uP would do it now. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
fast ramp follies
Started by ●August 14, 2012
Reply by ●August 18, 20122012-08-18
Reply by ●August 18, 20122012-08-18
Phil Hobbs a �crit :> dagmargoodboat@yahoo.com wrote: >> On Aug 15, 4:34 pm, Phil Hobbs >> <pcdhSpamMeSensel...@electrooptical.net> wrote: >> >> [...] >> >>> The NPN/PNP series-shunt pair (the one that folks with nothing better to >>> do are are slagging each other off about at the moment) runs the driver >>> transistor at constant I_C, and lets you use a much faster NPN to >>> stiffen the PNP at high frequency. Try simulating it--it's really good >>> medicine. >>> >>> (I spent most of July up to my ears in high performance laser noise >>> cancellers, which rely on a lot of those sorts of tricks, so I'm pretty >>> well up on all this at the moment.) >> I like the pseudo-Darlington, I'm just leery because I had those >> scream wickedly once using fast transistors. I don't think I ever >> fixed it. >> >> It has a bunch of advantages here, including reducing the base current >> i(b) error. >> >> Here's a skeleton idea for a Bloggs-Hobbs hybrid: >> >> Vcc Vcc >> -+- -+- >> | | >> | .-. R1 >> | U1 | | 120 >> | LM385 '-' >> | -adj | >> .---' | >> A<-----R2-----+---------. >> | | | >> | |<' Q1 | >> +-----+-----| BFT92 | >> | | |\ | >> R4 .-. --- C1 | |/ Q2 >> 1K | | --- +--f.b.-| BFP640 >> '-' | | |>. >> | === .-. | >> === | | R3 | >> '-' 600 | >> | | >> '---------+----> >> >> R2's a pathetic provision for isolating U1 from the nS stuff. The >> whole thing needs stabilizing against UHF oscillation, these are just >> the bones. >> >> -- >> Cheers, >> James Arthur > > It wouldn't need much more than that, I don't think. Series-shunt pairs > have poor stability when the transistors are about the same speed, due > to having two lags in the loop, but the BFP640 is ~10x faster than the > BFT92, which helps a lot. (Reducing the BFT92's collector current makes > the difference wider and helps with stability.) > > I used the BFP640 as a cascode for an ATF38143 pHEMT in a very quiet > charge-sensitive preamp (noise floor ~10 electrons per inverse > bandwidth), and all it needed was an 0402 bead in the base--no worries > at all. > > Cheers > > Phil Hobbs >I had a try at John's pb... Here it is, using a current source bootstrapped bootstrapped current source (yes I really meant to say that :-). I use the +8V/-5V supplies that you mentioned IIRC and only 3 x BFT92. Some temperature dependent biasing is also provided but I relied on the 8V supply stability over temp which may be wrong and you may have to adapt a bit. Some simulations including parasitics give pretty interesting results. Note that my BFT92 model VAF is 11V ! Is this low real ? (I don't have any to measure it) Despite this this circuit shows excellent results (in simulation, so apply the usual grain of salt). Still: * better than 0.1% linearity with this low VAF figure which can be further improved * start up transients are under 1ns and the integrated error is negligible... * 0.25% dispersion at 3.9V final value over temperature (-50/+75) (I relied on your 8V supply stability, so you may have to adapt a bit) * low output impedance, so no need for buffering if you just drive one input (modeled here as the 2pF capacitance) and can stand the temp dependent offset at start (or you can still add a NPN buffer to compensate for VBE) Here's a LTspice netlist. It's just for the drawing as I don't use it for sim and have almost no BJT models and even less with parasitics... If you want to see the results I'll make a pdf. ******************************************** Version 4 SHEET 1 948 1004 WIRE 16 32 -128 32 WIRE 96 32 16 32 WIRE 208 32 96 32 WIRE 416 32 208 32 WIRE 528 32 416 32 WIRE -128 48 -128 32 WIRE 16 48 16 32 WIRE 96 48 96 32 WIRE 208 48 208 32 WIRE -128 144 -128 128 WIRE -96 144 -128 144 WIRE 16 144 16 128 WIRE 16 144 -16 144 WIRE 16 176 16 144 WIRE 96 176 96 112 WIRE 96 176 16 176 WIRE 144 176 96 176 WIRE -128 224 -128 144 WIRE -48 224 -128 224 WIRE -128 256 -128 224 WIRE 880 304 112 304 WIRE 944 304 880 304 WIRE 16 336 16 272 WIRE 208 384 208 224 WIRE 240 384 208 384 WIRE 368 384 320 384 WIRE 784 384 368 384 WIRE 880 384 784 384 WIRE 944 384 880 384 WIRE 784 400 784 384 WIRE 368 416 368 384 WIRE 784 480 784 464 WIRE 208 496 208 384 WIRE 368 528 368 496 WIRE 640 528 368 528 WIRE 704 528 640 528 WIRE 368 560 368 528 WIRE 640 576 640 528 WIRE 704 576 704 528 WIRE 112 608 112 304 WIRE 112 608 -128 608 WIRE 208 608 208 576 WIRE 208 608 112 608 WIRE 304 608 208 608 WIRE -128 640 -128 608 WIRE 208 656 208 608 WIRE -176 704 -272 704 WIRE 368 704 368 656 WIRE 480 752 432 752 WIRE 528 752 480 752 WIRE 640 752 640 640 WIRE 640 752 608 752 WIRE 704 752 704 656 WIRE 704 752 640 752 WIRE -128 768 -128 736 WIRE 208 768 208 720 WIRE 480 784 480 752 WIRE 704 800 704 752 WIRE 480 880 480 848 WIRE 224 960 128 960 WIRE 368 960 368 800 WIRE 368 960 224 960 WIRE 704 960 704 880 WIRE 704 960 368 960 WIRE 848 960 704 960 FLAG 16 336 0 FLAG -128 336 0 FLAG 208 768 0 FLAG 784 480 0 FLAG 416 32 +8V_rail FLAG 224 960 -5V_rail FLAG 480 880 0 FLAG -128 768 0 FLAG 880 304 Out FLAG 880 384 LZ_Out SYMBOL pnp 144 224 M180 SYMATTR InstName Q1 SYMATTR Value BFT92 SYMBOL res 192 32 R0 SYMATTR InstName R1 SYMATTR Value 68R SYMBOL res 0 32 R0 SYMATTR InstName R2 SYMATTR Value 1.8K SYMBOL res 0 128 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 1K SYMBOL res -112 144 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R4 SYMATTR Value 1K SYMBOL res -112 352 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R5 SYMATTR Value 1.5K SYMBOL pnp -48 272 M180 SYMATTR InstName Q2 SYMATTR Value MMBT3906 SYMBOL cap 80 48 R0 SYMATTR InstName C1 SYMATTR Value 100n SYMBOL cap 192 656 R0 SYMATTR InstName C2 SYMATTR Value 10p SYMBOL pnp 304 656 M180 WINDOW 0 -19 136 Left 2 WINDOW 3 -20 111 Left 2 SYMATTR InstName Q3 SYMATTR Value BFT92 SYMBOL pnp 432 800 R180 WINDOW 0 117 63 Left 2 WINDOW 3 73 37 Left 2 SYMATTR InstName Q4 SYMATTR Value BFT92 SYMBOL res 224 480 M0 SYMATTR InstName R6 SYMATTR Value 82R SYMBOL res 336 368 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 10R SYMBOL ind 352 400 R0 SYMATTR InstName L1 SYMATTR Value 6.8nH SYMBOL cap 768 400 R0 SYMATTR InstName C3 SYMATTR Value 2p SYMBOL res 624 736 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R8 SYMATTR Value 100R SYMBOL res 688 560 R0 SYMATTR InstName R9 SYMATTR Value 10K SYMBOL res 688 784 R0 SYMATTR InstName R10 SYMATTR Value 6.2K SYMBOL cap 656 576 M0 SYMATTR InstName C4 SYMATTR Value 10n SYMBOL cap 464 784 R0 SYMATTR InstName C5 SYMATTR Value 0.2p SYMBOL njf -176 640 R0 SYMATTR InstName J1 SYMATTR Value NE3509 ******************************************** -- Thanks, Fred.
Reply by ●August 18, 20122012-08-18
On Aug 18, 3:57=A0pm, Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:> Bill Sloman wrote: > > On Aug 18, 7:03 am, John Larkin > > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > >>On Fri, 17 Aug 2012 19:38:35 -0700, josephkk > > >><joseph_barr...@sbcglobal.net> wrote: > > >>>On Fri, 17 Aug 2012 10:23:14 -0700, John Larkin > >>><jlar...@highlandtechnology.com> wrote: > > >>>>I invented a pseudo-inductor once, for one of the C5A projects of my > >>>>youth. To get the impedance up, I bootstrapped the base of a > >>>>darlington from its own emitter with a double RC. It oscillated at > >>>>some low frequency, 10 Hz or something. I didn't realize it at the > >>>>time, but I'd stumbled onto that RCRC circuit that has voltage gain. =I> >>>>fixed it without really understanding it. This was back in pre-Spice > >>>>days, when simulation was a chore. > > >>>A nit to pick, you aren't old enough to complain about pre-spice days, > >>>just not having access to it. =A0I know, i am about your age and knew =about> >>>spice in my early teens (my dad was an EE). =A0Many years later i had =my own> >>>spice 2.6g derivative; must have been 25 to 30 years ago. > > >>I hate to brag about how old I am, but Spice was introduced to the > >>world in 1973 > > >>http://en.wikipedia.org/wiki/SPICE#Origins > > >>I was simulating the throttle control system, turbine, propeller, and > >>hull dynamics of the LASH ships in 1968, while I was still an > >>undergrad at Tulane. I did initial sims on an HP9100 programmable > >>calculator, but soon cut over to a PDP8i running the FOCAL > >>interpretive language. > > >>http://www.pdp8.net/pdp8i/pdp8i.shtml > > > Sure. My Ph.D. work included the numerical integration of a couple of > > differential equations to model the the thermal decomposition of > > nitrosyle bromide - I wrote the program in 1968, and embedded it in a > > non-linear least squares minimisation program that adjusted the rate > > constant of the chemical reaction (as well as the initial and final > > concentrations of NOBr) to fit the various chunks experimental data > > (collected with different starting conditions and at different > > temperatures). > > =A0 With all the paper work you just claimed, how much from society did y=ou> rob over the years?Nothing. Everything that I've got was acquired honestly. The research grant that paid for my Ph.D. paid about half what I would have earned in industry, and rather less than half of what I did earn in industry as soon as I'd finished working on the Ph.D. At the time was seen as fair division of investment - society benefited from having people trained up to that level, because they contribute more once the start working, and I benefited from the higher salary that I'd eventually earn.> How much did you actually contribute to make the > world a better place?Hard to say. Odd things I worked on ended up doing useful stuff - the electron beam microfabricator that I played a small part in improving at Cambridge Instruments went on to make the masks for Farchild's 100k ECL and their 300k ECL, and another example of the same machine has been making the holograms for Australia's plastic banknotes for some twenty years now. My tidying-up work on the Metals Reserach GaAs crystal pullers, responsible for 95% of the single crystal GaAs produced in the west around 1990, seemed to make the puller run more smoothly and probably improved the quality of the GaAs crystals, but getting rid of 741 probably can't count for much in the scheme of things.> And how much did you actually work, period!Continuously and full time, from September 1969 to November 1991, when I got made redundant from Cambridge Instruments. I found full-time temporary work within ten days, but that petered out after a few months, and it wasn't until June 1992 that I found myself more full- time work, which kept me busy until my wife's new job moved us to the Netherlands in October 1993. I worked - nominally part-time - for Nijmegen University for the next six years and finally got myself a full time job in July 2000, which lasted until June 2003 - if I'd worked for Haffmans for more than 2 years and eleven months I'd have had a permanent job with them, which would have automatically made me a member of their pension fund, with the right to take immediate early retirement. Not unsurprisingly, the pension fund set the contribution that Haffmans would have had to pay on my behalf at a prohibitive level. The same ill-thought-out rules that lost me that job meant that I had the right to five years of unemployment benefit at 67% of my last salary, which kept me going until I hit 65. I was job-hunting all that time, but only got about one interview per year, and none of them turned into a job offer, which was irritating and frustrating.> =A0 =A0No bother to answer, most of us already know..You should know - I've told you before - but it doesn't interest you because it conflicts with the rubbish it suits you to believe.> =A0 Sounds like a lot of bull shit on paper if you ask me..It was certainly specialised work. The chance that you would have understood any of it is very low. There were several schematics in the appendices at the back of the thesis that you might understand, but I paid $30 for the first uA709 I used, and you can imagine that the designs have aged a bit (and weren't all that good at the time). There's also a couple of pages of Macro8 assembly language program for the PDP-8 which you certainly wouldn't understand, and a detailed discussion of how I implemented the Fletcher-Powell non-linear least square multi-parameter minimisation procedure which would also go over your head.> =A0 I too have paper work. But I keep it where it belongs, in the filing > cabinet because as far as I am concern it does not help me in > resolving issues from day to day and doing my job, a real job.That probably because you are as thick as brick. Specifying your problem before you start tackling it and documenting what you've done after you've tackled it are necessary parts of the design process. If they don't help you do your job, you aren't doing anything all that interesting, which may explain why you never talk about it here.> =A0 The only Phd I brag about is the one in my tool shed.You pile it higher and deeper around here too. -- Bill Sloman, Nijmegen
Reply by ●August 18, 20122012-08-18
On Sat, 18 Aug 2012 18:18:51 +0200, Fred Bartoli <" "> wrote:>Phil Hobbs a �crit : >> dagmargoodboat@yahoo.com wrote: >>> On Aug 15, 4:34 pm, Phil Hobbs >>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>> >>> [...] >>> >>>> The NPN/PNP series-shunt pair (the one that folks with nothing better to >>>> do are are slagging each other off about at the moment) runs the driver >>>> transistor at constant I_C, and lets you use a much faster NPN to >>>> stiffen the PNP at high frequency. Try simulating it--it's really good >>>> medicine. >>>> >>>> (I spent most of July up to my ears in high performance laser noise >>>> cancellers, which rely on a lot of those sorts of tricks, so I'm pretty >>>> well up on all this at the moment.) >>> I like the pseudo-Darlington, I'm just leery because I had those >>> scream wickedly once using fast transistors. I don't think I ever >>> fixed it. >>> >>> It has a bunch of advantages here, including reducing the base current >>> i(b) error. >>> >>> Here's a skeleton idea for a Bloggs-Hobbs hybrid: >>> >>> Vcc Vcc >>> -+- -+- >>> | | >>> | .-. R1 >>> | U1 | | 120 >>> | LM385 '-' >>> | -adj | >>> .---' | >>> A<-----R2-----+---------. >>> | | | >>> | |<' Q1 | >>> +-----+-----| BFT92 | >>> | | |\ | >>> R4 .-. --- C1 | |/ Q2 >>> 1K | | --- +--f.b.-| BFP640 >>> '-' | | |>. >>> | === .-. | >>> === | | R3 | >>> '-' 600 | >>> | | >>> '---------+----> >>> >>> R2's a pathetic provision for isolating U1 from the nS stuff. The >>> whole thing needs stabilizing against UHF oscillation, these are just >>> the bones. >>> >>> -- >>> Cheers, >>> James Arthur >> >> It wouldn't need much more than that, I don't think. Series-shunt pairs >> have poor stability when the transistors are about the same speed, due >> to having two lags in the loop, but the BFP640 is ~10x faster than the >> BFT92, which helps a lot. (Reducing the BFT92's collector current makes >> the difference wider and helps with stability.) >> >> I used the BFP640 as a cascode for an ATF38143 pHEMT in a very quiet >> charge-sensitive preamp (noise floor ~10 electrons per inverse >> bandwidth), and all it needed was an 0402 bead in the base--no worries >> at all. >> >> Cheers >> >> Phil Hobbs >> > > >I had a try at John's pb... > >Here it is, using a current source bootstrapped bootstrapped current >source (yes I really meant to say that :-). > >I use the +8V/-5V supplies that you mentioned IIRC and only 3 x BFT92. >Some temperature dependent biasing is also provided but I relied on the >8V supply stability over temp which may be wrong and you may have to >adapt a bit. > >Some simulations including parasitics give pretty interesting results. >Note that my BFT92 model VAF is 11V ! Is this low real ? (I don't have >any to measure it) > >Despite this this circuit shows excellent results (in simulation, so >apply the usual grain of salt). > >Still: >* better than 0.1% linearity with this low VAF figure which can be >further improved >* start up transients are under 1ns and the integrated error is >negligible... >* 0.25% dispersion at 3.9V final value over temperature (-50/+75) (I >relied on your 8V supply stability, so you may have to adapt a bit) >* low output impedance, so no need for buffering if you just drive one >input (modeled here as the 2pF capacitance) and can stand the temp >dependent offset at start (or you can still add a NPN buffer to >compensate for VBE) > > >Here's a LTspice netlist. It's just for the drawing as I don't use it >for sim and have almost no BJT models and even less with parasitics... > >If you want to see the results I'll make a pdf. > > >******************************************** > >Version 4 >SHEET 1 948 1004[snip .ASC, retrieve at Message-ID: <502fc06b$0$6124$426a74cc@news.free.fr>]>SYMATTR InstName J1 >SYMATTR Value NE3509 > > > >********************************************Finally! An inductor used properly. I can envision other such structures that are possibly simpler, but I ain'ta-gonna give Larkin no free ride ;-) Good job, Fred! ...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 18, 20122012-08-18
Bill Sloman wrote:> On Aug 18, 3:57 pm, Jamie > <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: > >>Bill Sloman wrote: >> >>>On Aug 18, 7:03 am, John Larkin >>><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >>>>On Fri, 17 Aug 2012 19:38:35 -0700, josephkk >> >>>><joseph_barr...@sbcglobal.net> wrote: >> >>>>>On Fri, 17 Aug 2012 10:23:14 -0700, John Larkin >>>>><jlar...@highlandtechnology.com> wrote: >> >>>>>>I invented a pseudo-inductor once, for one of the C5A projects of my >>>>>>youth. To get the impedance up, I bootstrapped the base of a >>>>>>darlington from its own emitter with a double RC. It oscillated at >>>>>>some low frequency, 10 Hz or something. I didn't realize it at the >>>>>>time, but I'd stumbled onto that RCRC circuit that has voltage gain. I >>>>>>fixed it without really understanding it. This was back in pre-Spice >>>>>>days, when simulation was a chore. >> >>>>>A nit to pick, you aren't old enough to complain about pre-spice days, >>>>>just not having access to it. I know, i am about your age and knew about >>>>>spice in my early teens (my dad was an EE). Many years later i had my own >>>>>spice 2.6g derivative; must have been 25 to 30 years ago. >> >>>>I hate to brag about how old I am, but Spice was introduced to the >>>>world in 1973 >> >>>>http://en.wikipedia.org/wiki/SPICE#Origins >> >>>>I was simulating the throttle control system, turbine, propeller, and >>>>hull dynamics of the LASH ships in 1968, while I was still an >>>>undergrad at Tulane. I did initial sims on an HP9100 programmable >>>>calculator, but soon cut over to a PDP8i running the FOCAL >>>>interpretive language. >> >>>>http://www.pdp8.net/pdp8i/pdp8i.shtml >> >>>Sure. My Ph.D. work included the numerical integration of a couple of >>>differential equations to model the the thermal decomposition of >>>nitrosyle bromide - I wrote the program in 1968, and embedded it in a >>>non-linear least squares minimisation program that adjusted the rate >>>constant of the chemical reaction (as well as the initial and final >>>concentrations of NOBr) to fit the various chunks experimental data >>>(collected with different starting conditions and at different >>>temperatures). >> >> With all the paper work you just claimed, how much from society did you >>rob over the years? > > > Nothing. Everything that I've got was acquired honestly. The research > grant that paid for my Ph.D. paid about half what I would have earned > in industry, and rather less than half of what I did earn in industry > as soon as I'd finished working on the Ph.D. At the time was seen as > fair division of investment - society benefited from having people > trained up to that level, because they contribute more once the start > working, and I benefited from the higher salary that I'd eventually > earn. > > >>How much did you actually contribute to make the >>world a better place? > > > Hard to say. Odd things I worked on ended up doing useful stuff - the > electron beam microfabricator that I played a small part in improving > at Cambridge Instruments went on to make the masks for Farchild's 100k > ECL and their 300k ECL, and another example of the same machine has > been making the holograms for Australia's plastic banknotes for some > twenty years now. > > My tidying-up work on the Metals Reserach GaAs crystal pullers, > responsible for 95% of the single crystal GaAs produced in the west > around 1990, seemed to make the puller run more smoothly and probably > improved the quality of the GaAs crystals, but getting rid of 741 > probably can't count for much in the scheme of things. > > >>And how much did you actually work, period! > > > Continuously and full time, from September 1969 to November 1991, when > I got made redundant from Cambridge Instruments. I found full-time > temporary work within ten days, but that petered out after a few > months, and it wasn't until June 1992 that I found myself more full- > time work, which kept me busy until my wife's new job moved us to the > Netherlands in October 1993. I worked - nominally part-time - for > Nijmegen University for the next six years and finally got myself a > full time job in July 2000, which lasted until June 2003 - if I'd > worked for Haffmans for more than 2 years and eleven months I'd have > had a permanent job with them, which would have automatically made me > a member of their pension fund, with the right to take immediate early > retirement. Not unsurprisingly, the pension fund set the contribution > that Haffmans would have had to pay on my behalf at a prohibitive > level. > > The same ill-thought-out rules that lost me that job meant that I had > the right to five years of unemployment benefit at 67% of my last > salary, which kept me going until I hit 65. I was job-hunting all that > time, but only got about one interview per year, and none of them > turned into a job offer, which was irritating and frustrating. > > >> No bother to answer, most of us already know.. > > > You should know - I've told you before - but it doesn't interest you > because it conflicts with the rubbish it suits you to believe. > > >> Sounds like a lot of bull shit on paper if you ask me.. > > > It was certainly specialised work. The chance that you would have > understood any of it is very low. There were several schematics in the > appendices at the back of the thesis that you might understand, but I > paid $30 for the first uA709 I used, and you can imagine that the > designs have aged a bit (and weren't all that good at the time). > There's also a couple of pages of Macro8 assembly language program for > the PDP-8 which you certainly wouldn't understand, and a detailed > discussion of how I implemented the Fletcher-Powell non-linear least > square multi-parameter minimisation procedure which would also go over > your head. > > >> I too have paper work. But I keep it where it belongs, in the filing >>cabinet because as far as I am concern it does not help me in >>resolving issues from day to day and doing my job, a real job. > > > That probably because you are as thick as brick. Specifying your > problem before you start tackling it and documenting what you've done > after you've tackled it are necessary parts of the design process. If > they don't help you do your job, you aren't doing anything all that > interesting, which may explain why you never talk about it here. > > >> The only Phd I brag about is the one in my tool shed. > > > You pile it higher and deeper around here too. > > -- > Bill Sloman, NijmegenOh believe me, no one and I mean no one can compete with you when it comes to piling it high. Jamie
Reply by ●August 18, 20122012-08-18
On Sat, 18 Aug 2012 09:46:55 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Sat, 18 Aug 2012 18:18:51 +0200, Fred Bartoli <" "> wrote: > >>Phil Hobbs a �crit : >>> dagmargoodboat@yahoo.com wrote: >>>> On Aug 15, 4:34 pm, Phil Hobbs >>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>> >>>> [...] >>>> >>>>> The NPN/PNP series-shunt pair (the one that folks with nothing better to >>>>> do are are slagging each other off about at the moment) runs the driver >>>>> transistor at constant I_C, and lets you use a much faster NPN to >>>>> stiffen the PNP at high frequency. Try simulating it--it's really good >>>>> medicine. >>>>> >>>>> (I spent most of July up to my ears in high performance laser noise >>>>> cancellers, which rely on a lot of those sorts of tricks, so I'm pretty >>>>> well up on all this at the moment.) >>>> I like the pseudo-Darlington, I'm just leery because I had those >>>> scream wickedly once using fast transistors. I don't think I ever >>>> fixed it. >>>> >>>> It has a bunch of advantages here, including reducing the base current >>>> i(b) error. >>>> >>>> Here's a skeleton idea for a Bloggs-Hobbs hybrid: >>>> >>>> Vcc Vcc >>>> -+- -+- >>>> | | >>>> | .-. R1 >>>> | U1 | | 120 >>>> | LM385 '-' >>>> | -adj | >>>> .---' | >>>> A<-----R2-----+---------. >>>> | | | >>>> | |<' Q1 | >>>> +-----+-----| BFT92 | >>>> | | |\ | >>>> R4 .-. --- C1 | |/ Q2 >>>> 1K | | --- +--f.b.-| BFP640 >>>> '-' | | |>. >>>> | === .-. | >>>> === | | R3 | >>>> '-' 600 | >>>> | | >>>> '---------+----> >>>> >>>> R2's a pathetic provision for isolating U1 from the nS stuff. The >>>> whole thing needs stabilizing against UHF oscillation, these are just >>>> the bones. >>>> >>>> -- >>>> Cheers, >>>> James Arthur >>> >>> It wouldn't need much more than that, I don't think. Series-shunt pairs >>> have poor stability when the transistors are about the same speed, due >>> to having two lags in the loop, but the BFP640 is ~10x faster than the >>> BFT92, which helps a lot. (Reducing the BFT92's collector current makes >>> the difference wider and helps with stability.) >>> >>> I used the BFP640 as a cascode for an ATF38143 pHEMT in a very quiet >>> charge-sensitive preamp (noise floor ~10 electrons per inverse >>> bandwidth), and all it needed was an 0402 bead in the base--no worries >>> at all. >>> >>> Cheers >>> >>> Phil Hobbs >>> >> >> >>I had a try at John's pb... >> >>Here it is, using a current source bootstrapped bootstrapped current >>source (yes I really meant to say that :-). >> >>I use the +8V/-5V supplies that you mentioned IIRC and only 3 x BFT92. >>Some temperature dependent biasing is also provided but I relied on the >>8V supply stability over temp which may be wrong and you may have to >>adapt a bit. >> >>Some simulations including parasitics give pretty interesting results. >>Note that my BFT92 model VAF is 11V ! Is this low real ? (I don't have >>any to measure it) >> >>Despite this this circuit shows excellent results (in simulation, so >>apply the usual grain of salt). >> >>Still: >>* better than 0.1% linearity with this low VAF figure which can be >>further improved >>* start up transients are under 1ns and the integrated error is >>negligible... >>* 0.25% dispersion at 3.9V final value over temperature (-50/+75) (I >>relied on your 8V supply stability, so you may have to adapt a bit) >>* low output impedance, so no need for buffering if you just drive one >>input (modeled here as the 2pF capacitance) and can stand the temp >>dependent offset at start (or you can still add a NPN buffer to >>compensate for VBE) >> >> >>Here's a LTspice netlist. It's just for the drawing as I don't use it >>for sim and have almost no BJT models and even less with parasitics... >> >>If you want to see the results I'll make a pdf. >> >> >>******************************************** >> >>Version 4 >>SHEET 1 948 1004 >[snip .ASC, retrieve at Message-ID: ><502fc06b$0$6124$426a74cc@news.free.fr>] >>SYMATTR InstName J1 >>SYMATTR Value NE3509 >> >> >> >>******************************************** > >Finally! An inductor used properly. I can envision other such >structures that are possibly simpler, but I ain'ta-gonna give Larkin >no free ride ;-)In other words, as usual, you contribute nothing on topic. All you remember how to do is boast and cluck. I don't think you could play the circuit design game if you wanted to. You are hiding your senility behind "not helping Larkin." You're useless off-chip anyhow.> >Good job, Fred! >So, you approve of Fred's design? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●August 18, 20122012-08-18
On Sat, 18 Aug 2012 18:18:51 +0200, Fred Bartoli <" "> wrote:>Phil Hobbs a �crit : >> dagmargoodboat@yahoo.com wrote: >>> On Aug 15, 4:34 pm, Phil Hobbs >>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>> >>> [...] >>> >>>> The NPN/PNP series-shunt pair (the one that folks with nothing better to >>>> do are are slagging each other off about at the moment) runs the driver >>>> transistor at constant I_C, and lets you use a much faster NPN to >>>> stiffen the PNP at high frequency. Try simulating it--it's really good >>>> medicine. >>>> >>>> (I spent most of July up to my ears in high performance laser noise >>>> cancellers, which rely on a lot of those sorts of tricks, so I'm pretty >>>> well up on all this at the moment.) >>> I like the pseudo-Darlington, I'm just leery because I had those >>> scream wickedly once using fast transistors. I don't think I ever >>> fixed it. >>> >>> It has a bunch of advantages here, including reducing the base current >>> i(b) error. >>> >>> Here's a skeleton idea for a Bloggs-Hobbs hybrid: >>> >>> Vcc Vcc >>> -+- -+- >>> | | >>> | .-. R1 >>> | U1 | | 120 >>> | LM385 '-' >>> | -adj | >>> .---' | >>> A<-----R2-----+---------. >>> | | | >>> | |<' Q1 | >>> +-----+-----| BFT92 | >>> | | |\ | >>> R4 .-. --- C1 | |/ Q2 >>> 1K | | --- +--f.b.-| BFP640 >>> '-' | | |>. >>> | === .-. | >>> === | | R3 | >>> '-' 600 | >>> | | >>> '---------+----> >>> >>> R2's a pathetic provision for isolating U1 from the nS stuff. The >>> whole thing needs stabilizing against UHF oscillation, these are just >>> the bones. >>> >>> -- >>> Cheers, >>> James Arthur >> >> It wouldn't need much more than that, I don't think. Series-shunt pairs >> have poor stability when the transistors are about the same speed, due >> to having two lags in the loop, but the BFP640 is ~10x faster than the >> BFT92, which helps a lot. (Reducing the BFT92's collector current makes >> the difference wider and helps with stability.) >> >> I used the BFP640 as a cascode for an ATF38143 pHEMT in a very quiet >> charge-sensitive preamp (noise floor ~10 electrons per inverse >> bandwidth), and all it needed was an 0402 bead in the base--no worries >> at all. >> >> Cheers >> >> Phil Hobbs >> > > >I had a try at John's pb... > >Here it is, using a current source bootstrapped bootstrapped current >source (yes I really meant to say that :-). > >I use the +8V/-5V supplies that you mentioned IIRC and only 3 x BFT92. >Some temperature dependent biasing is also provided but I relied on the >8V supply stability over temp which may be wrong and you may have to >adapt a bit. > >Some simulations including parasitics give pretty interesting results. >Note that my BFT92 model VAF is 11V ! Is this low real ? (I don't have >any to measure it) > >Despite this this circuit shows excellent results (in simulation, so >apply the usual grain of salt). > >Still: >* better than 0.1% linearity with this low VAF figure which can be >further improved >* start up transients are under 1ns and the integrated error is >negligible... >* 0.25% dispersion at 3.9V final value over temperature (-50/+75) (I >relied on your 8V supply stability, so you may have to adapt a bit) >* low output impedance, so no need for buffering if you just drive one >input (modeled here as the 2pF capacitance) and can stand the temp >dependent offset at start (or you can still add a NPN buffer to >compensate for VBE) > > >Here's a LTspice netlist. It's just for the drawing as I don't use it >for sim and have almost no BJT models and even less with parasitics... > >If you want to see the results I'll make a pdf. > > >******************************************** > >Version 4 >SHEET 1 948 1004 >WIRE 16 32 -128 32 >WIRE 96 32 16 32 >WIRE 208 32 96 32 >WIRE 416 32 208 32 >WIRE 528 32 416 32 >WIRE -128 48 -128 32 >WIRE 16 48 16 32 >WIRE 96 48 96 32 >WIRE 208 48 208 32 >WIRE -128 144 -128 128 >WIRE -96 144 -128 144 >WIRE 16 144 16 128 >WIRE 16 144 -16 144 >WIRE 16 176 16 144 >WIRE 96 176 96 112 >WIRE 96 176 16 176 >WIRE 144 176 96 176 >WIRE -128 224 -128 144 >WIRE -48 224 -128 224 >WIRE -128 256 -128 224 >WIRE 880 304 112 304 >WIRE 944 304 880 304 >WIRE 16 336 16 272 >WIRE 208 384 208 224 >WIRE 240 384 208 384 >WIRE 368 384 320 384 >WIRE 784 384 368 384 >WIRE 880 384 784 384 >WIRE 944 384 880 384 >WIRE 784 400 784 384 >WIRE 368 416 368 384 >WIRE 784 480 784 464 >WIRE 208 496 208 384 >WIRE 368 528 368 496 >WIRE 640 528 368 528 >WIRE 704 528 640 528 >WIRE 368 560 368 528 >WIRE 640 576 640 528 >WIRE 704 576 704 528 >WIRE 112 608 112 304 >WIRE 112 608 -128 608 >WIRE 208 608 208 576 >WIRE 208 608 112 608 >WIRE 304 608 208 608 >WIRE -128 640 -128 608 >WIRE 208 656 208 608 >WIRE -176 704 -272 704 >WIRE 368 704 368 656 >WIRE 480 752 432 752 >WIRE 528 752 480 752 >WIRE 640 752 640 640 >WIRE 640 752 608 752 >WIRE 704 752 704 656 >WIRE 704 752 640 752 >WIRE -128 768 -128 736 >WIRE 208 768 208 720 >WIRE 480 784 480 752 >WIRE 704 800 704 752 >WIRE 480 880 480 848 >WIRE 224 960 128 960 >WIRE 368 960 368 800 >WIRE 368 960 224 960 >WIRE 704 960 704 880 >WIRE 704 960 368 960 >WIRE 848 960 704 960 >FLAG 16 336 0 >FLAG -128 336 0 >FLAG 208 768 0 >FLAG 784 480 0 >FLAG 416 32 +8V_rail >FLAG 224 960 -5V_rail >FLAG 480 880 0 >FLAG -128 768 0 >FLAG 880 304 Out >FLAG 880 384 LZ_Out >SYMBOL pnp 144 224 M180 >SYMATTR InstName Q1 >SYMATTR Value BFT92 >SYMBOL res 192 32 R0 >SYMATTR InstName R1 >SYMATTR Value 68R >SYMBOL res 0 32 R0 >SYMATTR InstName R2 >SYMATTR Value 1.8K >SYMBOL res 0 128 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R3 >SYMATTR Value 1K >SYMBOL res -112 144 R180 >WINDOW 0 36 76 Left 2 >WINDOW 3 36 40 Left 2 >SYMATTR InstName R4 >SYMATTR Value 1K >SYMBOL res -112 352 R180 >WINDOW 0 36 76 Left 2 >WINDOW 3 36 40 Left 2 >SYMATTR InstName R5 >SYMATTR Value 1.5K >SYMBOL pnp -48 272 M180 >SYMATTR InstName Q2 >SYMATTR Value MMBT3906 >SYMBOL cap 80 48 R0 >SYMATTR InstName C1 >SYMATTR Value 100n >SYMBOL cap 192 656 R0 >SYMATTR InstName C2 >SYMATTR Value 10p >SYMBOL pnp 304 656 M180 >WINDOW 0 -19 136 Left 2 >WINDOW 3 -20 111 Left 2 >SYMATTR InstName Q3 >SYMATTR Value BFT92 >SYMBOL pnp 432 800 R180 >WINDOW 0 117 63 Left 2 >WINDOW 3 73 37 Left 2 >SYMATTR InstName Q4 >SYMATTR Value BFT92 >SYMBOL res 224 480 M0 >SYMATTR InstName R6 >SYMATTR Value 82R >SYMBOL res 336 368 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R7 >SYMATTR Value 10R >SYMBOL ind 352 400 R0 >SYMATTR InstName L1 >SYMATTR Value 6.8nH >SYMBOL cap 768 400 R0 >SYMATTR InstName C3 >SYMATTR Value 2p >SYMBOL res 624 736 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R8 >SYMATTR Value 100R >SYMBOL res 688 560 R0 >SYMATTR InstName R9 >SYMATTR Value 10K >SYMBOL res 688 784 R0 >SYMATTR InstName R10 >SYMATTR Value 6.2K >SYMBOL cap 656 576 M0 >SYMATTR InstName C4 >SYMATTR Value 10n >SYMBOL cap 464 784 R0 >SYMATTR InstName C5 >SYMATTR Value 0.2p >SYMBOL njf -176 640 R0 >SYMATTR InstName J1 >SYMATTR Value NE3509 > > > >********************************************Hi, Fred, I tried it but it won't run without the BFT92 model. Do you have that? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●August 18, 20122012-08-18
On Aug 18, 7:18=A0pm, Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:> BillSlomanwrote: > > On Aug 18, 3:57 pm, Jamie > > <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: > > >>BillSlomanwrote: > > >>>On Aug 18, 7:03 am, John Larkin > >>><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > >>>>On Fri, 17 Aug 2012 19:38:35 -0700, josephkk > > >>>><joseph_barr...@sbcglobal.net> wrote: > > >>>>>On Fri, 17 Aug 2012 10:23:14 -0700, John Larkin > >>>>><jlar...@highlandtechnology.com> wrote: > > >>>>>>I invented a pseudo-inductor once, for one of the C5A projects of m=y> >>>>>>youth. To get the impedance up, I bootstrapped the base of a > >>>>>>darlington from its own emitter with a double RC. It oscillated at > >>>>>>some low frequency, 10 Hz or something. I didn't realize it at the > >>>>>>time, but I'd stumbled onto that RCRC circuit that has voltage gain=. I> >>>>>>fixed it without really understanding it. This was back in pre-Spic=e> >>>>>>days, when simulation was a chore. > > >>>>>A nit to pick, you aren't old enough to complain about pre-spice day=s,> >>>>>just not having access to it. =A0I know, i am about your age and kne=w about> >>>>>spice in my early teens (my dad was an EE). =A0Many years later i ha=d my own> >>>>>spice 2.6g derivative; must have been 25 to 30 years ago. > > >>>>I hate to brag about how old I am, but Spice was introduced to the > >>>>world in 1973 > > >>>>http://en.wikipedia.org/wiki/SPICE#Origins > > >>>>I was simulating the throttle control system, turbine, propeller, and > >>>>hull dynamics of the LASH ships in 1968, while I was still an > >>>>undergrad at Tulane. I did initial sims on an HP9100 programmable > >>>>calculator, but soon cut over to a PDP8i running the FOCAL > >>>>interpretive language. > > >>>>http://www.pdp8.net/pdp8i/pdp8i.shtml > > >>>Sure. My Ph.D. work included the numerical integration of a couple of > >>>differential equations to model the the thermal decomposition of > >>>nitrosyle bromide - I wrote the program in 1968, and embedded it in a > >>>non-linear least squares minimisation program that adjusted the rate > >>>constant of the chemical reaction (as well as the initial and final > >>>concentrations of NOBr) to fit the various chunks experimental data > >>>(collected with different starting conditions and at different > >>>temperatures). > > >> =A0With all the paper work you just claimed, how much from society did=you> >>rob over the years? > > > Nothing. Everything that I've got was acquired honestly. The research > > grant that paid for my Ph.D. paid about half what I would have earned > > in industry, and rather less than half of what I did earn in industry > > as soon =A0as I'd finished working on the Ph.D. At the time was seen as > > fair division of investment - society benefited from having people > > trained up to that level, because they contribute more once the start > > working, and I benefited from the higher salary that I'd eventually > > earn. > > >>How much did you actually contribute to make the > >>world a better place? > > > Hard to say. Odd things I worked on ended up doing useful stuff - the > > electron beam microfabricator that I played a small part in improving > > at Cambridge Instruments went on to make the masks for Farchild's 100k > > ECL and their 300k ECL, and another example of the same machine has > > been making the holograms for Australia's plastic banknotes for some > > twenty years now. > > > My tidying-up work on the Metals Reserach GaAs crystal pullers, > > responsible for 95% of the single crystal GaAs produced in the west > > around 1990, seemed to make the puller run more smoothly and probably > > improved the quality of the GaAs crystals, but getting rid of 741 > > probably can't count for much in the scheme of things. > > >>And how much did you actually work, period! > > > Continuously and full time, from September 1969 to November 1991, when > > I got made redundant from Cambridge Instruments. I found full-time > > temporary work within ten days, but that petered out after a few > > months, and it wasn't until June 1992 that I found myself more full- > > time work, which kept me busy until my wife's new job moved us to the > > Netherlands in October 1993. I worked - nominally part-time - for > > Nijmegen University for the next six years =A0and finally got myself a > > full time job in July 2000, which lasted until June 2003 - if I'd > > worked for Haffmans for more than 2 years and eleven months I'd have > > had a permanent job with them, which would have automatically made me > > a member of their pension fund, with the right to take immediate early > > retirement. Not unsurprisingly, the pension fund set the contribution > > that Haffmans would have had to pay on my behalf at a prohibitive > > level. > > > The same ill-thought-out rules that lost me that job meant that I had > > the right to five years of unemployment benefit at 67% of my last > > salary, which kept me going until I hit 65. I was job-hunting all that > > time, but only got about one interview per year, and none of them > > turned into a job offer, which was irritating and frustrating. > > >> =A0 No bother to answer, most of us already know.. > > > You should know - I've told you before - but it doesn't interest you > > because it conflicts with the rubbish it suits you to believe. > > >> =A0Sounds like a lot of bull shit on paper if you ask me.. > > > It was certainly specialised work. The chance that you would have > > understood any of it is very low. There were several schematics in the > > appendices at the back of the thesis that you might understand, but I > > paid $30 for the first uA709 I used, and you can imagine that the > > designs have aged a bit (and weren't all that good at the time). > > There's also a couple of pages of Macro8 assembly language program for > > the PDP-8 which you certainly wouldn't understand, and a detailed > > discussion of how I implemented the Fletcher-Powell non-linear least > > square multi-parameter minimisation procedure which would also go over > > your head. > > >> =A0I too have paper work. But I keep it where it belongs, in the filin=g> >>cabinet because as far as I am concern it does not help me in > >>resolving issues from day to day and doing my job, a real job. > > > That probably is because you are as thick as brick. Specifying your > > problem before you start tackling it and documenting what you've done > > after you've tackled it are necessary parts of the design process. If > > they don't help you do your job, you aren't doing anything all that > > interesting, which may explain why you never talk about it here. > > >> =A0The only Phd I brag about is the one in my tool shed. > > > You pile it higher and deeper around here too. > > Oh believe me, no one and I mean no one can compete with you > when it comes to piling it high.But who is going to believe an ignorant and self-deluding idiot like you? -- Bill Sloman, Nijmegen
Reply by ●August 18, 20122012-08-18
On Sat, 18 Aug 2012 10:27:34 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>On Sat, 18 Aug 2012 09:46:55 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >>On Sat, 18 Aug 2012 18:18:51 +0200, Fred Bartoli <" "> wrote: >> >>>Phil Hobbs a �crit : >>>> dagmargoodboat@yahoo.com wrote: >>>>> On Aug 15, 4:34 pm, Phil Hobbs >>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>>> >>>>> [...] >>>>> >>>>>> The NPN/PNP series-shunt pair (the one that folks with nothing better to >>>>>> do are are slagging each other off about at the moment) runs the driver >>>>>> transistor at constant I_C, and lets you use a much faster NPN to >>>>>> stiffen the PNP at high frequency. Try simulating it--it's really good >>>>>> medicine. >>>>>> >>>>>> (I spent most of July up to my ears in high performance laser noise >>>>>> cancellers, which rely on a lot of those sorts of tricks, so I'm pretty >>>>>> well up on all this at the moment.) >>>>> I like the pseudo-Darlington, I'm just leery because I had those >>>>> scream wickedly once using fast transistors. I don't think I ever >>>>> fixed it. >>>>> >>>>> It has a bunch of advantages here, including reducing the base current >>>>> i(b) error. >>>>> >>>>> Here's a skeleton idea for a Bloggs-Hobbs hybrid: >>>>> >>>>> Vcc Vcc >>>>> -+- -+- >>>>> | | >>>>> | .-. R1 >>>>> | U1 | | 120 >>>>> | LM385 '-' >>>>> | -adj | >>>>> .---' | >>>>> A<-----R2-----+---------. >>>>> | | | >>>>> | |<' Q1 | >>>>> +-----+-----| BFT92 | >>>>> | | |\ | >>>>> R4 .-. --- C1 | |/ Q2 >>>>> 1K | | --- +--f.b.-| BFP640 >>>>> '-' | | |>. >>>>> | === .-. | >>>>> === | | R3 | >>>>> '-' 600 | >>>>> | | >>>>> '---------+----> >>>>> >>>>> R2's a pathetic provision for isolating U1 from the nS stuff. The >>>>> whole thing needs stabilizing against UHF oscillation, these are just >>>>> the bones. >>>>> >>>>> -- >>>>> Cheers, >>>>> James Arthur >>>> >>>> It wouldn't need much more than that, I don't think. Series-shunt pairs >>>> have poor stability when the transistors are about the same speed, due >>>> to having two lags in the loop, but the BFP640 is ~10x faster than the >>>> BFT92, which helps a lot. (Reducing the BFT92's collector current makes >>>> the difference wider and helps with stability.) >>>> >>>> I used the BFP640 as a cascode for an ATF38143 pHEMT in a very quiet >>>> charge-sensitive preamp (noise floor ~10 electrons per inverse >>>> bandwidth), and all it needed was an 0402 bead in the base--no worries >>>> at all. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>>> >>> >>> >>>I had a try at John's pb... >>> >>>Here it is, using a current source bootstrapped bootstrapped current >>>source (yes I really meant to say that :-). >>> >>>I use the +8V/-5V supplies that you mentioned IIRC and only 3 x BFT92. >>>Some temperature dependent biasing is also provided but I relied on the >>>8V supply stability over temp which may be wrong and you may have to >>>adapt a bit. >>> >>>Some simulations including parasitics give pretty interesting results. >>>Note that my BFT92 model VAF is 11V ! Is this low real ? (I don't have >>>any to measure it) >>> >>>Despite this this circuit shows excellent results (in simulation, so >>>apply the usual grain of salt). >>> >>>Still: >>>* better than 0.1% linearity with this low VAF figure which can be >>>further improved >>>* start up transients are under 1ns and the integrated error is >>>negligible... >>>* 0.25% dispersion at 3.9V final value over temperature (-50/+75) (I >>>relied on your 8V supply stability, so you may have to adapt a bit) >>>* low output impedance, so no need for buffering if you just drive one >>>input (modeled here as the 2pF capacitance) and can stand the temp >>>dependent offset at start (or you can still add a NPN buffer to >>>compensate for VBE) >>> >>> >>>Here's a LTspice netlist. It's just for the drawing as I don't use it >>>for sim and have almost no BJT models and even less with parasitics... >>> >>>If you want to see the results I'll make a pdf. >>> >>> >>>******************************************** >>> >>>Version 4 >>>SHEET 1 948 1004 >>[snip .ASC, retrieve at Message-ID: >><502fc06b$0$6124$426a74cc@news.free.fr>] >>>SYMATTR InstName J1 >>>SYMATTR Value NE3509 >>> >>> >>> >>>******************************************** >> >>Finally! An inductor used properly. I can envision other such >>structures that are possibly simpler, but I ain'ta-gonna give Larkin >>no free ride ;-) > >In other words, as usual, you contribute nothing on topic. All you >remember how to do is boast and cluck.Just as long as I keep you frothing at the mouth ;-)> >I don't think you could play the circuit design game if you wanted to. >You are hiding your senility behind "not helping Larkin." You're >useless off-chip anyhow. > >> >>Good job, Fred! >> > >So, you approve of Fred's design?I couldn't run it, but it certainly is heading in a better direction than all those insane IB correctors. What don't _you_ post your solution as an LTspice ASC file so that everyone can verify your brilliance ?:-) What have you designed lately? Yesterday I designed a magnetically controlled sign board :-) ...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 18, 20122012-08-18
John Larkin a �crit :> On Sat, 18 Aug 2012 18:18:51 +0200, Fred Bartoli <" "> wrote: > >> Phil Hobbs a �crit : >>> dagmargoodboat@yahoo.com wrote: >>>> On Aug 15, 4:34 pm, Phil Hobbs >>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>> >>>> [...] >>>> >>>>> The NPN/PNP series-shunt pair (the one that folks with nothing better to >>>>> do are are slagging each other off about at the moment) runs the driver >>>>> transistor at constant I_C, and lets you use a much faster NPN to >>>>> stiffen the PNP at high frequency. Try simulating it--it's really good >>>>> medicine. >>>>> >>>>> (I spent most of July up to my ears in high performance laser noise >>>>> cancellers, which rely on a lot of those sorts of tricks, so I'm pretty >>>>> well up on all this at the moment.) >>>> I like the pseudo-Darlington, I'm just leery because I had those >>>> scream wickedly once using fast transistors. I don't think I ever >>>> fixed it. >>>> >>>> It has a bunch of advantages here, including reducing the base current >>>> i(b) error. >>>> >>>> Here's a skeleton idea for a Bloggs-Hobbs hybrid: >>>> >>>> Vcc Vcc >>>> -+- -+- >>>> | | >>>> | .-. R1 >>>> | U1 | | 120 >>>> | LM385 '-' >>>> | -adj | >>>> .---' | >>>> A<-----R2-----+---------. >>>> | | | >>>> | |<' Q1 | >>>> +-----+-----| BFT92 | >>>> | | |\ | >>>> R4 .-. --- C1 | |/ Q2 >>>> 1K | | --- +--f.b.-| BFP640 >>>> '-' | | |>. >>>> | === .-. | >>>> === | | R3 | >>>> '-' 600 | >>>> | | >>>> '---------+----> >>>> >>>> R2's a pathetic provision for isolating U1 from the nS stuff. The >>>> whole thing needs stabilizing against UHF oscillation, these are just >>>> the bones. >>>> >>>> -- >>>> Cheers, >>>> James Arthur >>> It wouldn't need much more than that, I don't think. Series-shunt pairs >>> have poor stability when the transistors are about the same speed, due >>> to having two lags in the loop, but the BFP640 is ~10x faster than the >>> BFT92, which helps a lot. (Reducing the BFT92's collector current makes >>> the difference wider and helps with stability.) >>> >>> I used the BFP640 as a cascode for an ATF38143 pHEMT in a very quiet >>> charge-sensitive preamp (noise floor ~10 electrons per inverse >>> bandwidth), and all it needed was an 0402 bead in the base--no worries >>> at all. >>> >>> Cheers >>> >>> Phil Hobbs >>> >> >> I had a try at John's pb... >> >> Here it is, using a current source bootstrapped bootstrapped current >> source (yes I really meant to say that :-). >> >> I use the +8V/-5V supplies that you mentioned IIRC and only 3 x BFT92. >> Some temperature dependent biasing is also provided but I relied on the >> 8V supply stability over temp which may be wrong and you may have to >> adapt a bit. >> >> Some simulations including parasitics give pretty interesting results. >> Note that my BFT92 model VAF is 11V ! Is this low real ? (I don't have >> any to measure it) >> >> Despite this this circuit shows excellent results (in simulation, so >> apply the usual grain of salt). >> >> Still: >> * better than 0.1% linearity with this low VAF figure which can be >> further improved >> * start up transients are under 1ns and the integrated error is >> negligible... >> * 0.25% dispersion at 3.9V final value over temperature (-50/+75) (I >> relied on your 8V supply stability, so you may have to adapt a bit) >> * low output impedance, so no need for buffering if you just drive one >> input (modeled here as the 2pF capacitance) and can stand the temp >> dependent offset at start (or you can still add a NPN buffer to >> compensate for VBE) >> >> >> Here's a LTspice netlist. It's just for the drawing as I don't use it >> for sim and have almost no BJT models and even less with parasitics... >> >> If you want to see the results I'll make a pdf. >> >> >> ******************************************** >> >> Version 4 >> SHEET 1 948 1004 >> WIRE 16 32 -128 32<< ... >>>> SYMBOL njf -176 640 R0 >> SYMATTR InstName J1 >> SYMATTR Value NE3509 >> >> >> >> ******************************************** > > > Hi, Fred, > > I tried it but it won't run without the BFT92 model. Do you have that? >As I said I don't have them for LTspice, so it's why this netlist don't run flat. But they are available from the Infineon datasheet, with all the parasitics... (I don't know how to do build a new model for ltspice) You'd have to build a subcircuit for the SOT23 parasitics and include the die model. Here is the one from the spice database I used. .SUBCKT BFT92s 200 100 300 ** ^ ^ ^ ** C B E ** *SOT23 Q1 2 1 3 BFT92Xm LBI 1 10 0.85NH LEI 3 30 0.69NH CCB 10 2 84FF CCE 2 30 165FF CBE 10 30 73FF LBO 10 100 0.51NH LCO 2 200 0.49NH LEO 30 300 0.61NH .MODEL BFT92Xm PNP( + IS = 4.5354E-15 BF = 98.533 NF = 0.90551 + VAF = 10.983 IKF = 0.016123 ISE = 1.2196E-14 + NE = 1.1172 BR = 10.297 NR = 1.2703 + VAR = 47.577 IKR = 0.019729 ISC = 2.4709E-17 + NC = 1.206 RB = 7.9562 IRB = 0.00079584 + RBM = 1.5939 RE = 1.5119 RC = 0.66749 + CJE = 1.7785E-15 VJE = 0.79082 MJE = 0.32167 + TF = 3.2171E-11 XTF = 0.30227 VTF = 0.21451 + ITF = 1.3277E-05 PTF = 0 CJC = 9.2207E-13 + VJC = 1.2 MJC = 0.3 XCJC = 0.3 + TR = 2.0779E-09 CJS= 0 VJS = 0.75 + MJS = 0 XTB = 0 EG = 1.11 + XTI = 3 FC = 0.75167) .ENDS Note that on my database model CBE is specified but is missing from the datasheet that you can find here http://www.farnell.com/datasheets/62457.pdf (probably a datasheet error) That 73fF value is coherent with what can be expected from a SOT23 package so it probably is right. You can try with and without it, but in this circuit it probably don't matter much. -- Thanks, Fred.
