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bootstrap analog multiplexer

Discussion in 'Electronic Design' started by gravpoet, Mar 15, 2007.

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  1. gravpoet

    gravpoet Guest

    I need an analog multiplexer that can process ±40V DC voltage
    inputs...any ideas ?

    I've seen some info on bootstrapping of op amp supplies to get higher
    output voltages...I'm wondering if this technique or something similar
    can be applicable to to analog multiplexers ?

  2. Joerg

    Joerg Guest

    Nope, you just buy'em :)

    Supertex makes HV muxes:
  3. gravpoet

    gravpoet Guest

    Thanks for your input.

    The mux is at the (+) input of an op amp configured as a voltage
    follower. My design requires 1GΩ of input impedance minimum which
    would preclude resistor type attenuators. I am assuming that is what
    you were referring to. I may have better luck looking for an accurate
    "active" attenuator (?).

    The Supertex devices in the previous post may be a good
    solution...I'll have to review the specs.
  4. There's also the possibility of using optically-switched
    MOSFET switches, some of these are quite good for signals.
    You mention a 1G Zin requirement, what about I_leakage
    and capacitive-loading specs, anything there?

    What are you working on?
  5. GravityPoet

    GravityPoet Guest

    This is an input circuit to a general purpose data acquisition board.
    The output of the analog multiplexer is buffered with a voltage
    follower (AD8512) in order to meet input requirements of 1GΩ input
    impedance and input leakage
    < 0.5µA.

    The output of the voltage follower then feeds a level shifter/
    attenuator ckt that differentially drives a 24-bit ADC.

    Thanks for the help.
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