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sigma delta ADC

Discussion in 'General Electronics Discussion' started by beheshte, Aug 4, 2013.

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  1. beheshte

    beheshte

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    Aug 4, 2013
    Hi, I'm new here. I will be appreciated if anyone can help me.
    I want to design a discrete-time noise-coupled sigma delta modulator. so I need an adder before the quantizer, that has a path with one cycle delay. In the articles I've seen, this adder is realized with an active adder. Is it possible to realize it with a passive adder? I mean is there a passive adder which has a path with one cycle delay?
    thanks
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    What do you mean by active or passive adder?
    Can you show us a reference circuit diagram so we talk about the same things?
     
  3. beheshte

    beheshte

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    Aug 4, 2013
    To realize an active adder we use an Op-Amp and some switches and capacitors but a passive adder doesn't need an Op-Amp.It is realized just with some switches and capacitors.
    In the paper called "ΔΣ ADCs with Second-Order Noise-Shaping Enhancement" figure.4 shows an active adder with one cycle delay.This is the address of the above paper:
    http://ieeexplore.ieee.org/xpl/logi...5230480/5235877/05236085.pdf?arnumber=5236085
    I want to realize this circuit without using an Op-Amp, I mean by a passive adder.
     
  4. beheshte

    beheshte

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    Aug 4, 2013
    And also in the paper addressed below,figure.16 and figure.17 shows a passive and active adder respectively:
    http://onlinelibrary.wiley.com/doi/10.1002/cta.1816/abstract
    In fig.16 the switches and capacitors at front end make the passive adder.The Op-Amp after that does not belong to the passive adder .That is preamp for the quantizer and can be removed.
     
  5. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Neither of those documents is accessible without a membership to the web site.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    I don't know of a "passive adder" (in your terms) that would be reasonably accurate for use in an ADC.
    I, too, do not have access to the linked documents.
     
  7. beheshte

    beheshte

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    Aug 4, 2013
    I will send you these articles if you could give me your email addresses
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Do not send them to any of us, post them here using the attachment function (you need to "go advanced" for this).
    On the other hand, since these articles are behind a paywall, they are most probably copyrighted. Make yure you have the right to post them or to send them to others. Or redraw the relevant schematic parts to avoid copyright infringement.
     
  9. beheshte

    beheshte

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    Aug 4, 2013
    These articles are free for the students of our university because our university is a member of those websites. So they paid for them.But I'm not sure that I can share them. That was the reason that I wanted to send them as an email for you, not to share them in a public website. So if it is possible for you,I send them for you as an email.
    thanks anyway
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Please do not send them. rfedraw the relevant schematic and post it on the forum so others too can see it.
     
  11. beheshte

    beheshte

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    Aug 4, 2013
    I attached a file that includes the circuit diagram of mentioned adders
     

    Attached Files:

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