Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #454253

Re: OpAmp design - from theory to practice

Show all headers | View raw

On 30/03/2017 18:45, Joerg wrote:
> On 2017-03-29 07:55, Francesco Zappon wrote:
>> Hello everyone,
>>
>> first post here. I hope I do not break any rule; let me know if this
>> is the case.
>>
>
> There are not many rules out here anymore :-)
>
> <ducking for cover now>
>
>
>> Disclaimer: not native English speaker, forgive any mistake.
>>
>
> Your English looks very good (I am non-native myself).
>
>
>> My background: master degree in physics (with a few courses in
>> electronics). PhD in electronics/physics, doing 99% of digital
>> design. My last encounter with analog design: 10 years ago (ie: my
>> knowledge is a bit "rusty").
>>
>> The problem: I work in high energy physics. Currently, my new project
>> is to design a new version (in a new technology: from 250nm to 130nm)
>
>
> 130nm isn't considered very new these days but, of course, for radhard
> your selection will be limited. New designs are still done in the larger
> geometries. The most recent one I was involved in was 300nm.
>
>
>> of a chip which has to perform current-to-frequency (CFC from now on)
>> conversion. (for background information, if interested, you can read
>> the previous designer work here:
>> http://dx.doi.org/10.1016/j.mejo.2013.08.020 if you have access).
>>
>
> Do you have a link where this paper can be accessed without charge? From
> non-subscribers they want about $40 just to take a look.
>
>
>> Basically, I need to design a CFC with input currents ranging from
>> 1nA to 1mA, with a 40 us integration window and low input leakage
>> (target: 100fA). Other details can be provided if needed.
>>
>> The main problem is the design of the amplifier. I am studying the
>> common designs and the usual architectures; BUT I have a difficult
>> time in connecting the high-level specification of the device (CFC,
>> min/max input current, etc..) with the low level specs of the
>> amplifier (a fully differential OTA, if we keep the previous
>> architecture) such as GBP, phase margin, slew rate, etc...
>>
>
> 1nA gets you into noise floor issues with the first stage if the
> integration window means >20kHz bandwidth.
>
>
>> I understand that there is no such thing as a "magical" formula to
>> design such circuits, but I assume that there must be, somewhere, a
>> point from where to start, which is what I am missing here.
>>
>> All the examples and designs I see (in tutorials or articles) start
>> from the wanted specifications of the OpAmp, which would be good, if
>> I had an idea on how to obtain them!
>>
>> I hope that the question make sense to you.
>>
>> Any help you can give is greatly appreciated!
>>
>
> Usually the first stage needed would be a transimpedance amplifier or
> TIA, in other words a glorified current to voltage converter, followed
> by a V/F conversion or another more modern method. Phil Hobbs here in
> this group is the guru on low noise TIAs, maybe he could chime in.
>
> It might also help to talk to these guys:
>
> http://ams.aeroflex.com/pagesproduct/datasheets/MilAero_ASIC_Brochure.pdf
>

https://www.dropbox.com/s/52nqfror1jhkqm0/venturini2013.pdf?dl=0

Back to sci.electronics.design | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

OpAmp design - from theory to practice Francesco Zappon <cescozep@gmail.com> - 2017-03-29 07:55 -0700
  Re: OpAmp design - from theory to practice Tim Wescott <tim@seemywebsite.com> - 2017-03-29 11:51 -0500
  Re: OpAmp design - from theory to practice Tim Wescott <tim@seemywebsite.com> - 2017-03-29 11:53 -0500
    Re: OpAmp design - from theory to practice Francesco Zappon <cescozep@gmail.com> - 2017-03-30 01:02 -0700
      Re: OpAmp design - from theory to practice Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-30 10:54 +0100
        Re: OpAmp design - from theory to practice sroberts6328@gmail.com - 2017-03-30 05:25 -0700
      Re: OpAmp design - from theory to practice Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-03-30 14:37 +0200
        Re: OpAmp design - from theory to practice Francesco Zappon <cescozep@gmail.com> - 2017-03-30 07:16 -0700
          Re: OpAmp design - from theory to practice Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-03-30 20:25 +0200
            Re: OpAmp design - from theory to practice bitrex <bitrex@de.lete.earthlink.net> - 2017-03-30 14:51 -0400
            Re: OpAmp design - from theory to practice Joerg <news@analogconsultants.com> - 2017-03-30 12:58 -0700
              Re: OpAmp design - from theory to practice pcdhobbs@gmail.com - 2017-03-30 13:25 -0700
              Re: OpAmp design - from theory to practice Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-03-30 23:55 +0200
                Re: OpAmp design - from theory to practice Joerg <news@analogconsultants.com> - 2017-03-30 16:43 -0700
          Re: OpAmp design - from theory to practice George Herold <gherold@teachspin.com> - 2017-03-30 11:43 -0700
            Re: OpAmp design - from theory to practice Francesco Zappon <cescozep@gmail.com> - 2017-03-30 15:02 -0700
            Re: OpAmp design - from theory to practice Jeroen Belleman <jeroen@nospam.please> - 2017-03-31 10:20 +0200
      Re: OpAmp design - from theory to practice Tim Wescott <tim@seemywebsite.com> - 2017-03-30 12:14 -0500
        Re: OpAmp design - from theory to practice Francesco Zappon <cescozep@gmail.com> - 2017-03-30 15:05 -0700
  Re: OpAmp design - from theory to practice Joerg <news@analogconsultants.com> - 2017-03-30 10:45 -0700
    Re: OpAmp design - from theory to practice JM <dontreplytothis173@gmail.com> - 2017-03-30 19:32 +0100
      Re: OpAmp design - from theory to practice Joerg <news@analogconsultants.com> - 2017-03-30 12:47 -0700
        Re: OpAmp design - from theory to practice Francesco Zappon <cescozep@gmail.com> - 2017-03-30 15:16 -0700
          Re: OpAmp design - from theory to practice George Herold <gherold@teachspin.com> - 2017-03-30 16:11 -0700
          Re: OpAmp design - from theory to practice Joerg <news@analogconsultants.com> - 2017-03-30 16:57 -0700

csiph-web