This circuit produces an output from 21 V to 25 V as the input varies from 0 mV to 100 mV. The first op amp stage is an inverting summing amplifier combining a low-voltage input and a DC offset, while the second stage is a unity-gain inverter that flips the output back to a positive range. Sufficient power supply rails (above 25 V) are essential to prevent saturation and ensure the desired output.
