Temperature drift on volatge divider built with resistors from the same series

Question

I am in the process of designing a data acquisition device that will be used outdoors, with temperature swings of around 30 degrees.

For this i need to scale the input to a voltage suitable to the adc and reference i am using, the initial offset of the circuit is a non issue as it will be calibrated out, however what concerns me is the temperature drift.

One way to be sure the drift won't be a problem would be to use resistors with a very low Tc, these usually are pretty expensive if i want a drift of less than 0.02% over the temperature range, so i was wondering if it was reasonable to assume that by using resistors of the same series and keeping them at the same temperature one could assume the drift will be reasonably equal in both hence canceling out or if that assumption is completely erroneous.

Thanks

Answer 1

You could do it like this (resistor values can be scaled to whatever, obviously, just R and 8*R required):

^{simulate this circuit – Schematic created using CircuitLab}

Since R5 is 24x the value of R1||R2||R3, its tempco will have very little effect on the tempco of the divider.