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current amp speed adjustment

Steve Robalino
Prodigy 110 points
Other Parts Discussed in Thread: THS3091, OPA695, THS4031

Im currenlty using the THS3091D - it has proven to be too fast for the layout of the current board. What is the next slower speed device that has the same voltage specs (in an SOIC-8 pkg) or next two slower speeds....

 

Thanks in advance

  • 0
    TI__Expert 4950 points

    Steve,

    Because the THS3091 is a current feedback amplifier, you can control the speed (BW) of the amplifier by increasing the feedback resistance from the value provided in the datasheet spec table.

    RF = 1.78 kΩ, for unity gain

    RF = 1.21 kΩ, for gain of 2V/V

    RF = 1 kΩ, for a gain of 5V/V

    RF = 866 Ω, for a gain of 10V/V

    The theory behind setting the feedback resistance can be found in the OPA695 datasheet on page 23 under the heading "Setting resistor value to optimize the bandwidth".

    If by too fast, you imply that the THS3091 is oscillating, you may want to consider a voltage feedback amplifier to start debuggin your board.  The THS4031 may be a good place to start.