Differential amp circuit outputting positive voltage regardless of polarity

[king.oslo]

Hello there,

An op-amp voltage subtractor outputs a negative voltage if the inverting input voltage is greater than the non-inverting input voltage.

I want to make a circuit which always always subtracts the lowest voltage from the highest voltage. I want to always get a positive output. How can I do that elegantly? It doesn't need to use an op-amp, but its got to have less than 1mV input offset and high speed.

What do you suggest?

Thank you for your time.

Kind regards,
Marius

[chrome]

Differential opamp followed by an opamp rectifier ?

[erupter]

Check this link by Elliot Sound Products for precision rectifiers.