Single Supply OP AMP

Discussion in 'General Electronics Chat' started by Alex009, Jul 2, 2014.

  1. Alex009

    Thread Starter Member

    Jul 2, 2014
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    Hey guys im currently trying to amplify an Input-Signal with the range of:
    0-8V and a maximum frequency of 100kHz. I need to get a signal with the range of 0 to -0.4 V ..which means i need and inverting op amp circuit.
    The problem is: i only got a single supply of 24 V. Is it possible to realize this result without using a virtual mass - since this causes issues with following devices.
    BR
    Alex
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Hi Alex,

    What do you mean by virtual mass - virtual ground....??
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    The next question then is where the 0 to -0.4V output fits with the overall scheme.

    If you only have a uni-polar 24V DC supply is this the same supply operating the downstream electronics / "following devices"? Or does that part of your circuit operate off a bi-polar supply?

    You will probably need to give more information to receive a suitable reply.
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    hi alex,
    You say Fmax input of 100kHz, whats the lowest Freq input.?
    Also is it a sinewave or some other form.??

    E
     
  5. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    hi alex,
    The way I was thinking you could design an AC coupled amplifier if the frequency range was not so low.

    The problem with a virtual ground OPA common rail splitting into +/-12Vdc is that the 24Vdc would not be usable for any other device without some hassle if you intend connecting other 'DC' circuits to the 24V supply.

    Can you give us more info on the App.? a diagram ?
    E
     
  6. Alex009

    Thread Starter Member

    Jul 2, 2014
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    Well i could try to get you a diagram of the electric board ( how its currently done ) if you give me a few hours - Could that help you?
     
  7. Alec_t

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    Sep 17, 2013
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    Could you use a switched-cap negative voltage generator such as a MAX1044/ICL7660, so as to have a bipolar supply for signal conditioning?
     
  8. Alex009

    Thread Starter Member

    Jul 2, 2014
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    I m not sure if i just opened the same document as you did, but how would you make sure that you "exactly" get -12 V and + 12 V to have a bipolar supply (besides that there is an absolute maximum input of 10.5V)?

    // Just read the "such as" part my bad

    // that could actually work..cheers for the tip

    // But still would be nice if a cheaper solution could be found..
     
    Last edited: Jul 2, 2014
  9. Alec_t

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    Sep 17, 2013
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    Post deleted
     
    Last edited: Jul 2, 2014
  10. Alec_t

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    Sep 17, 2013
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    The +ve and -ve voltages don't have to match. Since your min voltage is -0.4 the -ve supply need be only a few volts. You could have, for example, a +24V/-5V supply for an opamp, like this:
     
  11. Alex009

    Thread Starter Member

    Jul 2, 2014
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    Cheers Alec ,
    i m gonna simulate the whole circuit (hopefully) until saturday night. As soon as im done with this i ll reply again (either with new questions or telling you that the problem has been solved - in theory).
     
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