Offset voltage is the first DC error this module will look at. Offset voltage adds a small voltage in series with the input signal. The offset voltage may be as small as a few microvolts, but it is multiplied by the op amp’s gain. Op Amp applications that require a high gain are more susceptible to offset voltage error than applications with low gain requirements. The offset voltage can be positive or negative, and is caused by a mismatching between the input transistors of the amplifier. To measure the offset voltage, the op amp is configured for a very high gain and the inputs are tied to ground. Then output voltage is then measured and divide by the noise gain.