Reply by John Larkin January 20, 20172017-01-20
On Fri, 20 Jan 2017 08:28:36 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Fri, 20 Jan 2017 07:14:46 -0800, John Larkin ><jjlarkin@highlandtechnology.com> wrote: > >>On Fri, 20 Jan 2017 08:40:46 +0000, Martin Brown >><|||newspam|||@nezumi.demon.co.uk> wrote: >> >>>On 18/01/2017 20:37, tabbypurr@gmail.com wrote: >>>> Jim Thompson wrote >>>> >>>> >>>>> Math ?? If you're only a user, you can write down all you need to >>>>> know about OpAmps in a couple of pages. >>>>> >>>>> ...Jim Thompson >>>> >>>> I'd be very interested in that. So lets see what would need to be covered: >>>> >>>> The basic idea of what an opamp is and how closing the loop enables it to do all sorts. >>>> Understanding the specs >>> >>>TI have quite a nice paper by Jim Karki on the differences between the >>>idealised mathematicians perfect OPAMP and their engineering reality. >>> >>>http://www.ti.com/lit/an/sloa011/sloa011.pdf >> >>The 'e' component in LT Spice is almost an ideal opamp. > >The 'E' component is in _all_ Berkeley-compliant Spice variants. 'E' >alone gives fake results because it has no roll-off, or, almost more >importantly, doesn't have a 90&#2013266096; phase shift.
It works fine for DC analysis. If you want a rolloff, add an RC at the output. Its advantage over UniversalOpamp2 is that it doesn't need power supplies. There used to be a UniversalOpamp that didn't need supplies, I think, but it's gone. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by Jim Thompson January 20, 20172017-01-20
On Fri, 20 Jan 2017 07:14:46 -0800, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

>On Fri, 20 Jan 2017 08:40:46 +0000, Martin Brown ><|||newspam|||@nezumi.demon.co.uk> wrote: > >>On 18/01/2017 20:37, tabbypurr@gmail.com wrote: >>> Jim Thompson wrote >>> >>> >>>> Math ?? If you're only a user, you can write down all you need to >>>> know about OpAmps in a couple of pages. >>>> >>>> ...Jim Thompson >>> >>> I'd be very interested in that. So lets see what would need to be covered: >>> >>> The basic idea of what an opamp is and how closing the loop enables it to do all sorts. >>> Understanding the specs >> >>TI have quite a nice paper by Jim Karki on the differences between the >>idealised mathematicians perfect OPAMP and their engineering reality. >> >>http://www.ti.com/lit/an/sloa011/sloa011.pdf > >The 'e' component in LT Spice is almost an ideal opamp.
The 'E' component is in _all_ Berkeley-compliant Spice variants. 'E' alone gives fake results because it has no roll-off, or, almost more importantly, doesn't have a 90&#2013266096; phase shift. "Op-Amp-Config.zip" on the Device Models & Subcircuits page of my website presents a fair representation of real OpAmps... and is configurable by the user by simply inputting datasheet information. It is several generations old... I have newer versions that are quite accurate, but require a "spreadsheet" to obtain the coefficients of the model. I do not share the spreadsheet. only the application-specific subcircuit >:-} ...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 | I'm looking for work... see my website. Thinking outside the box... producing elegant solutions.
Reply by John Larkin January 20, 20172017-01-20
On Fri, 20 Jan 2017 08:40:46 +0000, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

>On 18/01/2017 20:37, tabbypurr@gmail.com wrote: >> Jim Thompson wrote >> >> >>> Math ?? If you're only a user, you can write down all you need to >>> know about OpAmps in a couple of pages. >>> >>> ...Jim Thompson >> >> I'd be very interested in that. So lets see what would need to be covered: >> >> The basic idea of what an opamp is and how closing the loop enables it to do all sorts. >> Understanding the specs > >TI have quite a nice paper by Jim Karki on the differences between the >idealised mathematicians perfect OPAMP and their engineering reality. > >http://www.ti.com/lit/an/sloa011/sloa011.pdf
The 'e' component in LT Spice is almost an ideal opamp. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by Martin Brown January 20, 20172017-01-20
On 18/01/2017 20:37, tabbypurr@gmail.com wrote:
> Jim Thompson wrote > > >> Math ?? If you're only a user, you can write down all you need to >> know about OpAmps in a couple of pages. >> >> ...Jim Thompson > > I'd be very interested in that. So lets see what would need to be covered: > > The basic idea of what an opamp is and how closing the loop enables it to do all sorts. > Understanding the specs
TI have quite a nice paper by Jim Karki on the differences between the idealised mathematicians perfect OPAMP and their engineering reality. http://www.ti.com/lit/an/sloa011/sloa011.pdf -- Regards, Martin Brown
Reply by January 19, 20172017-01-19
On Thursday, 19 January 2017 22:49:54 UTC, Jim Thompson  wrote:
> On Thu, 19 Jan 2017 13:54:47 -0800 (PST), tabbypurr wrote: > >On Wednesday, 18 January 2017 20:37:26 UTC, tabby wrote: > >> Jim Thompson wrote > >> > >> > >> > Math ?? If you're only a user, you can write down all you need to > >> > know about OpAmps in a couple of pages. > >> > > >> > ...Jim Thompson > > > >I reckon you were right. Just *** big pages :) > > > > > >NT > > Yep. I wrongly supposed that the readers here didn't need help with > applications >:-} > > ...Jim Thompson
Yeah, it's more for complete beginners. NT
Reply by Jim Thompson January 19, 20172017-01-19
On Thu, 19 Jan 2017 13:54:47 -0800 (PST), tabbypurr@gmail.com wrote:

>On Wednesday, 18 January 2017 20:37:26 UTC, tabby wrote: >> Jim Thompson wrote >> >> >> > Math ?? If you're only a user, you can write down all you need to >> > know about OpAmps in a couple of pages. >> > >> > ...Jim Thompson > >I reckon you were right. Just *** big pages :) > > >NT
Yep. I wrongly supposed that the readers here didn't need help with applications >:-} ...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 | I'm looking for work... see my website. Thinking outside the box... producing elegant solutions.
Reply by January 19, 20172017-01-19
On Wednesday, 18 January 2017 20:37:26 UTC, tabby  wrote:
> Jim Thompson wrote > > > > Math ?? If you're only a user, you can write down all you need to > > know about OpAmps in a couple of pages. > > > > ...Jim Thompson
I reckon you were right. Just *** big pages :) NT
Reply by Phil Hobbs January 19, 20172017-01-19
On 01/19/2017 12:27 PM, piglet wrote:
> On 19/01/2017 17:01, Phil Hobbs wrote: >> >> There was a boosted 741 as well--741S, maybe? >> > > Was that the uA748 ? > > I actually specified 741 in a new design as recently as 2006 for an > undemanding application simply because they were so incredibly cheap and > multi-sourced. > > piglet >
The 748 is just a 741 with an external compensation cap. This one had (iirc) about 5 V/us slew rate, vs. 0.3 or 0.5 for the 741. 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
Reply by piglet January 19, 20172017-01-19
On 19/01/2017 17:01, Phil Hobbs wrote:
> > There was a boosted 741 as well--741S, maybe? >
Was that the uA748 ? I actually specified 741 in a new design as recently as 2006 for an undemanding application simply because they were so incredibly cheap and multi-sourced. piglet
Reply by Jim Thompson January 19, 20172017-01-19
On Thu, 19 Jan 2017 12:01:48 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 01/19/2017 11:15 AM, Jim Thompson wrote: >> On Thu, 19 Jan 2017 04:59:27 -0800 (PST), pcdhobbs@gmail.com wrote: >> >>>> Are there any op-amps with say a 800V/uS slew rate but a GBWP of >>>> like 1kHz? >>> >>> Well, you can reduce the effective GBW by increasing the noise >>> gain. In an inverting amp, if your feedback resistor is 1M, putting >>> 1k from the summing junction to ground will make it 1000 times >>> slower. It'll also have 1000 times the offset and noise. >>> >>> Slew rate is unaffected, but of course it'll need a big input >>> voltage to get it to maximum slew. >>> >>> For a normal unity-gain-stable bipolar op amp with pole splitting >>> and no emitter degeneration or >> >>> current-booster funnies in the input stage, >> >> Such as some ancient Burr-Brown designs which switched in extra >> current for a large differential input. > >There was a boosted 741 as well--741S, maybe?
I don't remember that one.
> >> >>> the slew limit is always near 0.3V*GBW. >> >> For GBW in MHz and "modern" architectures. My venerable MC1530 >> (still sold by Lansdale) has ~10MHz and 10V/us, but sports a zero in >> the compensation and voltage gain after the pole. >> >> Current mode feedback OpAmps are different. For instance Apex PB64 >> has ~3MHz GBW, but 800V/us slew-rate for large step inputs. > >Apart from the noise and offset, a CFB behaves a lot like a VFB with >that small resistor to ground from the SJ--the bandwidth is almost >independent of the gain. That's how I usually think of them. > >Cheers > >Phil Hobbs
Yep. Constant risetime instead of flat slew-rate. Got in big hassle with a customer that didn't understand that :-( ...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 | I'm looking for work... see my website. Thinking outside the box... producing elegant solutions.