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Opamps - everything

Started by Unknown January 18, 2017
On Wednesday, January 18, 2017 at 6:59:43 PM UTC-5, John Larkin wrote:
> On Wed, 18 Jan 2017 12:37:23 -0800 (PST), 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 > >The different types > >static sensitivity > >info on popular opamps > > > >Circuits: > >inv amp > >noninv amp > >integrator > >differentiator > >gyrator > >clippers > >dc restorers > >log > >class B amps, various > >" with crossover distortion reduction > >Mr Larkin's optoisolator booster > >assorted power supply regulators > >instrumentation amp > >endless oscillators > >analogue computation, various > >security lights > >precision rectifier > >ECG > >EEG > >biofeedback > > > > > >Techniques: > >stability > >dealing with offsets > >increasing rf gain > >eliminating crossover disotrtion in opamps > >making opamps go R2R > >capacitive loads > >positive feedback > >hysteresis > >opamp v comparator > >protection against the outside world > >agc > >The other 3 types, current conveyor etc > >discrete opamps maybe > >bias > >femtoamp measuring > >PSRR > >opamps with issues > >choppers > >load impedance > >precision > > > > > >I'm sure I've missed a ton of stuff. Anyone? > > > > > >NT > > > Add a section: weird opamps.
Bad opamps, (got an email from a HV opamp maker, wanting to visit.. no thanks.) Oh I would add opamp output impedance to the list. I talked (email) with a burr-brown tech guy answering questions.. output impedance is complex and the basic test circuit measures the total impedance, I wanted the resistive part. (I ended up measuring by just loading it down.) George H.
> > > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com
On Wednesday, 18 January 2017 21:15:38 UTC, Winfield Hill  wrote:
> tabbypurr wrote...
> > I'm sure I've missed a ton of stuff. Anyone? > > Very important, a practical matter that costs me > tons of time: > Specifications: - what opamps have what specs, > tradeoffs in specs, implications of certain specs. > And very useful, what's going on inside the opamp > to achieve the specs. > > Also important: > Circuit tricks to avoid degrading said specs. > > Yes, I think there's enough for a book. One of the > useful topics in Dostal's book, how to measure opamp > specs. There's 40 pages in one section, many more > in other sections.
I don't think I could do those topics justice. I mainly see opamps as black boxes. Well, maybe not in that I understand the 2 or 3 stages in them, but how the variants relate to differing specs/issues I only have partial knowledge of. NT
On Wed, 18 Jan 2017 17:26:06 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Wed, 18 Jan 2017 15:59:33 -0800, John Larkin ><jjlarkinxyxy@highlandtechnology.com> wrote: > >[snip] > >>Add a section: weird opamps. > >What OpAmps would you consider weird? > >Those with three stages of gain ?>:-} > > ...Jim Thompson
C-load, advertised or not High voltage Low voltage High current Clamp-amps Outrageous bandwidth, 1 GHz or so fA bias current Low noise High noise Especially buggy -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
>>Add a section: weird opamps.
>What OpAmps would you consider weird?
>Those with three stages of gain ?>:-}
LM324--class B plus weirdness due to bias generator shared between all sections; LT1028--nice and quiet but with a weird gigantic noise peak near 300 kHz, plus squirrelly compensation due to 3 gain stages; Chopamps and their *ahem* unexpected current noise peaks; ADSL drivers like the one John has been posting about; TCA0372--dual 1.4 A op amps in an SO-14 package with no power pad; MC33078/9: super cheap, quiet, single-supply, but with 300 nA input bias current; Those TI CMOS things with the noisy internal bootstrap that have super low input capacitance but horrible current noise; All the FET amps whose datasheets quote the current noise as being the shot noise of the typical input bias current. There are lots more. Cheers Phil Hobbs
On Wed, 18 Jan 2017 16:55:42 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Wednesday, January 18, 2017 at 6:59:43 PM UTC-5, John Larkin wrote: >> On Wed, 18 Jan 2017 12:37:23 -0800 (PST), 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 >> >The different types >> >static sensitivity >> >info on popular opamps >> > >> >Circuits: >> >inv amp >> >noninv amp >> >integrator >> >differentiator >> >gyrator >> >clippers >> >dc restorers >> >log >> >class B amps, various >> >" with crossover distortion reduction >> >Mr Larkin's optoisolator booster >> >assorted power supply regulators >> >instrumentation amp >> >endless oscillators >> >analogue computation, various >> >security lights >> >precision rectifier >> >ECG >> >EEG >> >biofeedback >> > >> > >> >Techniques: >> >stability >> >dealing with offsets >> >increasing rf gain >> >eliminating crossover disotrtion in opamps >> >making opamps go R2R >> >capacitive loads >> >positive feedback >> >hysteresis >> >opamp v comparator >> >protection against the outside world >> >agc >> >The other 3 types, current conveyor etc >> >discrete opamps maybe >> >bias >> >femtoamp measuring >> >PSRR >> >opamps with issues >> >choppers >> >load impedance >> >precision >> > >> > >> >I'm sure I've missed a ton of stuff. Anyone? >> > >> > >> >NT >> >> >> Add a section: weird opamps. >Bad opamps, (got an email from a HV opamp maker, >wanting to visit.. no thanks.)
Apex?
> >Oh I would add opamp output impedance to the list. >I talked (email) with a burr-brown tech guy >answering questions.. output impedance is complex >and the basic test circuit measures the total impedance, >I wanted the resistive part. (I ended up measuring >by just loading it down.)
Open-loop Zout can be interesting. Open-loop behavior of opamps can be interesting in general. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Wed, 18 Jan 2017 17:20:47 -0800 (PST), pcdhobbs@gmail.com wrote:

>>>Add a section: weird opamps. > >>What OpAmps would you consider weird? > >>Those with three stages of gain ?>:-} > >LM324--class B plus weirdness due to bias generator shared between all sections;
Plus, fun things happen all over the chip if one pin is pulled slightly below ground.
> >LT1028--nice and quiet but with a weird gigantic noise peak near 300 kHz, plus squirrelly compensation due to 3 gain stages; > >Chopamps and their *ahem* unexpected current noise peaks; > >ADSL drivers like the one John has been posting about;
I suppose THS3062 can work as an ADSL line driver, but don't use it for anything else!
> >TCA0372--dual 1.4 A op amps in an SO-14 package with no power pad;
But lots of pins to heat sink! -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Wednesday, January 18, 2017 at 8:21:36 PM UTC-5, John Larkin wrote:
> On Wed, 18 Jan 2017 16:55:42 -0800 (PST), George Herold > <gherold@teachspin.com> wrote: > > >On Wednesday, January 18, 2017 at 6:59:43 PM UTC-5, John Larkin wrote: > >> On Wed, 18 Jan 2017 12:37:23 -0800 (PST), 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 > >> >The different types > >> >static sensitivity > >> >info on popular opamps > >> > > >> >Circuits: > >> >inv amp > >> >noninv amp > >> >integrator > >> >differentiator > >> >gyrator > >> >clippers > >> >dc restorers > >> >log > >> >class B amps, various > >> >" with crossover distortion reduction > >> >Mr Larkin's optoisolator booster > >> >assorted power supply regulators > >> >instrumentation amp > >> >endless oscillators > >> >analogue computation, various > >> >security lights > >> >precision rectifier > >> >ECG > >> >EEG > >> >biofeedback > >> > > >> > > >> >Techniques: > >> >stability > >> >dealing with offsets > >> >increasing rf gain > >> >eliminating crossover disotrtion in opamps > >> >making opamps go R2R > >> >capacitive loads > >> >positive feedback > >> >hysteresis > >> >opamp v comparator > >> >protection against the outside world > >> >agc > >> >The other 3 types, current conveyor etc > >> >discrete opamps maybe > >> >bias > >> >femtoamp measuring > >> >PSRR > >> >opamps with issues > >> >choppers > >> >load impedance > >> >precision > >> > > >> > > >> >I'm sure I've missed a ton of stuff. Anyone? > >> > > >> > > >> >NT > >> > >> > >> Add a section: weird opamps. > >Bad opamps, (got an email from a HV opamp maker, > >wanting to visit.. no thanks.) > > Apex?
I've got a tray of expensive noisy HV opamps. Apex doesn't want them back. now replaced by LT(6090?) at ~$10 or so. George H.
> > > > >Oh I would add opamp output impedance to the list. > >I talked (email) with a burr-brown tech guy > >answering questions.. output impedance is complex > >and the basic test circuit measures the total impedance, > >I wanted the resistive part. (I ended up measuring > >by just loading it down.) > > Open-loop Zout can be interesting. > > Open-loop behavior of opamps can be interesting in general. > > > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com
George Herold wrote...
> > I've got a tray of expensive noisy HV opamps. > Apex doesn't want them back. now replaced > by LT(6090?) at ~$10 or so.
My HV amplifier designs have input stages that run on +/-12V or 15V, and good performance. In Apex designs, input stage common-mode works over the whole HV range. They use special parts to achieve this, and many are noisy. APEX amps are easy to use (although very expensive). They can do the low-noise accurate job, when paired with a low-voltage op-amp. We're talking about simple composite op-amps, two stages, where the quiet low-offset input stage runs from low-voltage supplies and the HV op-amp runs the output stage. Often the input op-amp can be in a SOT-23 package, taking little space. -- Thanks, - Win
On 01/18/2017 08:20 PM, pcdhobbs@gmail.com wrote:
>>> Add a section: weird opamps. > >> What OpAmps would you consider weird? > >> Those with three stages of gain ?>:-} > > LM324--class B plus weirdness due to bias generator shared between all sections; > > LT1028--nice and quiet but with a weird gigantic noise peak near 300 kHz, plus squirrelly compensation due to 3 gain stages; > > Chopamps and their *ahem* unexpected current noise peaks; > > ADSL drivers like the one John has been posting about; > > TCA0372--dual 1.4 A op amps in an SO-14 package with no power pad; > > MC33078/9: super cheap, quiet, single-supply, but with 300 nA input bias current; > > Those TI CMOS things with the noisy internal bootstrap that have super low input capacitance but horrible current noise; > > All the FET amps whose datasheets quote the current noise as being the shot noise of the typical input bias current. > > There are lots more. > > Cheers > > Phil Hobbs >
Are there any op-amps with say a 800V/uS slew rate but a GBWP of like 1kHz?
On Wed, 18 Jan 2017 18:01:15 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Wednesday, January 18, 2017 at 8:21:36 PM UTC-5, John Larkin wrote: >> On Wed, 18 Jan 2017 16:55:42 -0800 (PST), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Wednesday, January 18, 2017 at 6:59:43 PM UTC-5, John Larkin wrote: >> >> On Wed, 18 Jan 2017 12:37:23 -0800 (PST), 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 >> >> >The different types >> >> >static sensitivity >> >> >info on popular opamps >> >> > >> >> >Circuits: >> >> >inv amp >> >> >noninv amp >> >> >integrator >> >> >differentiator >> >> >gyrator >> >> >clippers >> >> >dc restorers >> >> >log >> >> >class B amps, various >> >> >" with crossover distortion reduction >> >> >Mr Larkin's optoisolator booster >> >> >assorted power supply regulators >> >> >instrumentation amp >> >> >endless oscillators >> >> >analogue computation, various >> >> >security lights >> >> >precision rectifier >> >> >ECG >> >> >EEG >> >> >biofeedback >> >> > >> >> > >> >> >Techniques: >> >> >stability >> >> >dealing with offsets >> >> >increasing rf gain >> >> >eliminating crossover disotrtion in opamps >> >> >making opamps go R2R >> >> >capacitive loads >> >> >positive feedback >> >> >hysteresis >> >> >opamp v comparator >> >> >protection against the outside world >> >> >agc >> >> >The other 3 types, current conveyor etc >> >> >discrete opamps maybe >> >> >bias >> >> >femtoamp measuring >> >> >PSRR >> >> >opamps with issues >> >> >choppers >> >> >load impedance >> >> >precision >> >> > >> >> > >> >> >I'm sure I've missed a ton of stuff. Anyone? >> >> > >> >> > >> >> >NT >> >> >> >> >> >> Add a section: weird opamps. >> >Bad opamps, (got an email from a HV opamp maker, >> >wanting to visit.. no thanks.) >> >> Apex? >I've got a tray of expensive noisy HV opamps. >Apex doesn't want them back. >now replaced by LT(6090?) at ~$10 or so.
Apex has a company culture of delivering very strange, buggy, noisy opamps. It's their niche. -- John Larkin Highland Technology, Inc lunatic fringe electronics