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I want to convert a temperature dependent current from a PT100 into a temperature dependent voltage. I opted for a transimpedance amplifier, but it gives me a negative voltage. How can I construct a circuit that does not give me a negative voltage without using a second opamp?

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  • \$\begingroup\$ This is going to be highly dependent on the details of the current source, I think. If it must work into a virtual ground (rather than, say, a small resistance that keeps the voltage within some acceptable range) it may not be possible. If you can use a resistance, the solution is trivial, just a non-inverting amplifier with a shunt resistance on the input. \$\endgroup\$ Commented Nov 30, 2020 at 19:41
  • \$\begingroup\$ @SpehroPefhany Thank you. I wanted it to work into virtual ground, but I'm not limited to that \$\endgroup\$
    – Maxim
    Commented Nov 30, 2020 at 19:48
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    \$\begingroup\$ If the temperature dependent current comes from a temperature dependent resistance connected to V+ this is easy. Connect it to V- instead (duly observing polarity). Then the inversion produces a +ve output voltage. \$\endgroup\$
    – user16324
    Commented Nov 30, 2020 at 20:10
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    \$\begingroup\$ @Maxim Please provide the current source (sensor) for the input of the transimepedance amp \$\endgroup\$
    – Voltage Spike
    Commented Nov 30, 2020 at 20:32
  • \$\begingroup\$ Transimpedance amplifiers invert. You are asking for something that probably isn't really what you want. I want a car with only 2 wheels; it's called a bike (for example). \$\endgroup\$
    – Andy aka
    Commented Dec 1, 2020 at 9:53

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