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I've been looking into precision ground reference circuits to form ±5V rails from a 10V supply for a project I'm working on, and noticed that current feedback (CFB) op-amps have some desirable characteristics (primarily high output current and slew rate). Since I will be using it as a return path for multiple filters and decoupling capacitors, it needs to have a high output current and fast settling time. However, I also need keep the DC level stable across a range of temperatures and under varying loading conditions.

I like the dual-feedback design below that a voltage feedback op-amp, but I also have a few concerns:

  • The suggested precision op-amp has a low slew rate. This could be problematic since I am expecting (unavoidable) step changes at the output.
  • With the series resistor, I'm afraid that the op-amp will saturate before it can source or sink sufficient current.

schematic

simulate this circuit – Schematic created using CircuitLab

Questions:

  • Can I safely route the inverting input of a CFB to a distant part of the board (as a Kelvin connection)?
  • Assuming that I can guarantee stability under capacitive loading conditions, am I likely to run into DC drift issues (possibly due to self-heating)? I don't care about the initial DC offset as long as it is very stable.
  • After setting the feedback resistor, can I still expect to get a high slew rate?

I'm thinking of doing something like this to generate a ground reference using a CFB op-amp (possibly the LT1206 or LT1217):

schematic

simulate this circuit

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  • \$\begingroup\$ Ahh that recognizable sound of a can of worms being opened. This is not the right route; use a voltage regulator or justify why you can't. \$\endgroup\$ – Andy aka Jun 1 '18 at 17:52
  • \$\begingroup\$ @Andyaka I thought of that as I was writing the question, but I'm concerned that a regulator would not be able to handle step changes quickly enough. I will need to run some simulations. \$\endgroup\$ – Caleb Reister Jun 1 '18 at 18:08
  • \$\begingroup\$ Step changes are handled by the regulators output capacitor as with any type of voltage regulation including using an opamp. \$\endgroup\$ – Andy aka Jun 1 '18 at 18:41

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