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Low signal voltage boost circuit

Dig
I need to boost a 0-100mV, or less, analog signal into to 0-10V that a DAC can read. My budget is low, so the simplest solution is needed. Off the shelf solutions are ok too.
 
Possibly a step-up/down IC or an OP-AMP?
 
Dig
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  • 0

    Hi,

     

    Did you mean an ADC?   I think an op-amp circuit configured for a gain of 100 would probably be the easiest approach.   Do you have a 10V supply available on the board?  10V seems a tad on the high side for an ADC input.

     

    But anyway, a step-up or boost converter would just step that up to a pre-set output voltage, so if you are trying to measure a variation in the input analog signal, you wouldn't be able to capture that accuratel, 100mV is also really low for any boost regulators on the market.

     

    If you have control over the reference voltage of the ADC you could lower that to increase your resolution so you wouldn't necessarily need to amplify your signal so high.

     

    The best solution though would be to just go with a generic op-amp and configure it for the gain you need.

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  • 0

    Hi,

     

    Did you mean an ADC?   I think an op-amp circuit configured for a gain of 100 would probably be the easiest approach.   Do you have a 10V supply available on the board?  10V seems a tad on the high side for an ADC input.

     

    But anyway, a step-up or boost converter would just step that up to a pre-set output voltage, so if you are trying to measure a variation in the input analog signal, you wouldn't be able to capture that accuratel, 100mV is also really low for any boost regulators on the market.

     

    If you have control over the reference voltage of the ADC you could lower that to increase your resolution so you wouldn't necessarily need to amplify your signal so high.

     

    The best solution though would be to just go with a generic op-amp and configure it for the gain you need.

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  • 0 in reply to Former Member

    Wormius,

     

    Thanks for the reply. DAC is a data acquisition module. The one my company wants to use does not read the variations that are that small. A new DAC is impossible for many reasons.

    So, I need to divide up the 0-100mV in the 0-10V I need. Approximately 10mV per 1V deviation.

     

    image

    I drew the above non-inverting op-amp in MS Paint, excuse the quality.

     

    Gain is A = 1 + (Rf/R2) = 10

     

    Just making R2 = 1K

    Rf must be 9k

     

    Simple as this?

     

    Dig

  • 0 in reply to Dig

    It could be as simple as that but what is the input signal bandwidth?  At a gain of 100 across your opamp you will have to check carefully that you will get the gain you are expecting because of bandwidth limiting.  This is a non issue if you are measuring DC levels but as soon as you have an AC component to capture it becomes a real issue.

     

    Also - you may want to consider some input filtering, without filtering any input noise is going to be amplified 100 times as well as your signal which will reduce your DAC's effective sensitivity.

     

    William

    http://www.labtronix.co.uk