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High bandwidth current source (inductive load, 1A max.)

Ahmet Okyay
Prodigy 20 points


Hello,

I want to build a Voltage Controlled Current Source for controlling the current running through an inductive load specified as:

-Z1: 25 mH + 5 Ohm.

Also,

- Low noise needed.

- 1A max. current

- 250 Hz bandwidth from voltage to current.

Which amplifiers would you suggest for such a circuit? Do you have any reference designs?

  • 0
    Prodigy 10 points

    You know that building a current source driving an inductive load is very similar to loading an op amp with a capacitor: It will create another pole and cause instability in the feedback loop.  One good way to design it would be to use an uncompensated op amp and arrange for the dominate pole to be created by the output load.  This technique is similar to the semiconductor companies who make op amps that are "stable with any capacitive load" .  

    Another significant challenge is the difficulty of making the current sense resistor non-inductive.