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ISO120 100kHz BW boost component selection

Fatin Haque
Prodigy 80 points
Other Parts Discussed in Thread: ISO120

Hi,

 

The ISO120 has an application note to boost the BW of the device to 100kHz (which is what I need). I plan to use the ISO amp to separate an amplified signal from an amplifier stage (between 1-5V) and the oscilloscope to break the ground loop. So I guess the current requirements are not so high since I'm basically doing a voltage reading at 100kHz bandwidth. 

1) However, I want to pick passive components that will contribute small noise and handle the power requirements of that circuit. Do you have suggestions on the type of power I need for the passive components and the type of passive components that I will need? (ie. film vs. carbon resistors, capacitor types, etc).

2) On another note, the power requirements show +-15V supplies. But, I want to run this amplifier circuit using batteries and preferably with only 1 supply. Is this possible? What do you recommend for the power? Would I require any regulation or can I use a simple passive regulation of the battery power?

 

 

Thanks!

  • 0
    Guru 21975 points

    Fatin,

    I'm trying to put this question in the context of your second question, posted a while later... Current Suppression Techniques before Amplification of a Low Noise Signal

    Is there a high voltage present between the input and output of the isolation amplifier? Why must you "break the ground loop?"

    Given the very tiny signals you are trying to acquire, the ISO120 may not be the best approach.

    Regards, Bruce


     

  • 0 in reply to Bruce Trump
    Prodigy 80 points

    Thanks for the reply.

     

    What I am trying to do is measure RTS / 1/f noise in a MOSFET. This current signal is on the order of a few nA. But, I need to drive Ids to different values on the MOSFET IV curve (triode region, and weak inversion). This signal needs to go into some current preamplifier that can take this small signal and amplify it enough to be detected by the oscilloscope.

     

    The isolation amplifier would be placed between the amplifier and the oscilloscope since the power supplies biasing the MOSFET is on a different ground than the oscilloscope. So, the input of the ISO would be a few volts (1-5V) and the output would be of the same order (unity gain).