# Can this analog voltage be scaled and shifted to the new range using op amps with only ±12V power supplies?

I have an analog voltage signal which is in the range [+2.1875 V ... +2.8125 V], centered around 2.5 V. I would like to scale and shift this signal so that it is mapped to the range [-3V ... +3V], and now centered around zero volts.

I am happy to use multiple op amps, but am constrained to using ± 12V power supplies. Is this possible?

• Not really a limitation since regulators exist. Feb 18, 2022 at 15:21
• Yes absolutely. Given a +/-12V power supply you can produce voltages within the -12 to +12V. In this case you'd add a -2.5V DC offset and then amplify by 9.6X. Feb 18, 2022 at 15:21
• Thank you - can you provide a sketch / schematic of the arrangement in an answer? Feb 18, 2022 at 15:24
• Does this answer your question? Change range of a DC signal without changing the offset with op amps The other guy's answer is better though even though mine was marked at best. My approach is just easier to follow but less efficient circuit. This asks to not change the offset but it's all the same anyways since offset fiddling is needed to keep it the same anyways due to amplification/scaling. Feb 18, 2022 at 15:24
• Possibly. I am looking to scale the signal and center it around zero though. Does this need to be first done with a subtraction of 2.5V, and then a second op amp for the scaling. Or can it be done with one op amp? An sketch with example resistors would be great... Thank you :) Feb 18, 2022 at 15:29

can it be done with one op amp?

If one op. amp. and one cheap voltage reference would be acceptable, the circuit below includes all the formulas, which were initially based on this TI app. note..

There is an implicit connection between RS, RK, RR and RG: RS must guarantee enough current goes through the TL431 reference, so, if RG is too small, the feedback resistor should be increased. If RR is too large, the current that enters the "ref pin" should be taken into account. Finally, for the same reason, if the current through RK is too large, RS should be decreased.

So, this is not (yet) fully automatic. If there is not enough current entering the K pin of the voltage reference, check the resistor values or increase the current through RS (set to 10 mA in the equations).

As stated in the comment, this circuit topology works for positive gain (max > min in both input and output) and negative shift output midpoint is lower than input midpoint.

These are the results for the selected input parameters: