Non-Inverting Op-Amp Level Shifter. Figure 463.1 shows the basic connection for developing a fixed 400mv ±1% reference voltage from any supply voltage in the range of 1.4v to 18v. If you apply the offset first, then the you would need:

Using a unity gain op amp you can achieve the desired results the same as the above circuit by using. Differential amplifier that performs a signal level shift proportional to the voltage vshift. So r1 and r2 form a voltage divider, and r2.