RTD Thermistor fine tuning circuit

[Adam12]

Hi,

I'm looking for help designing a circuit that can fine tune/calibrate the output of an RTD Thermistor. Looking for an accuracy of 0.1 ohms and a linear range of 0 to 10 ohms. I thought it would be as easy as a single POT but I can't seem to find the part with those specs.

What's it for?
I have 3 RTD thermistor temperature probes that feed one PID(MYPIN TA4 temperature process control module). I'm using rotary knobs to switch between probes and there is a 0-2 degrees fahrenheit temperature variance between the probes that I hope to null with this circuit. I'll duplicate this circuit and apply it to two of the RTD's to match the "master" RTD.

Thanks for any help.
Adam12

[pebe]

One of the parameters of a FET is its ON resistance. When switched on it can have a resistance of less than 1ohm. That resistance can be increased by varying the gate voltage (using a pot). For more details, read this link.
https://en.wikipedia.org/wiki/Field-effect_transistor

You could then fit the FET in series with your thermistor to raise the total resistance. Unfortunately, the change in ON resistance is not linear with change in gate voltage, but you may find it useful.