Example below shows the output offset computation equation for the noninverting configuration using the typical bias current and offset specifications for A_V = +2:

Output Offset: V_O = (±I_BN × R_IN ± V_IO) (1 + R_F/R_G) ± I_BI × R_F

Where R_IN is the equivalent input impedance on the noninverting input.

Example computation for A_V = +2, R_F = 237Ω, R_IN = 25Ω:

V_O = (±6μA × 25Ω ± 1mV) (1 + 237/237) ± 8μA × 237 = ±4.20mV

A good design, however, includes a worst-case calculation using minimum and maximum numbers in the data sheet tables to provide worst-case operation.

Further improvement in the output offset voltage and drift is possible using composite amplifiers. The two input bias currents are physically unrelated in both magnitude and polarity for the current feedback topology. Therefore, to cancel the effects by matching the source impedance for the two inputs (as is commonly done for matched input bias current devices) is not possible.

The total output noise is computed in a similar fashion to the output offset voltage. Using the input noise voltage and the two input noise currents, the output noise is developed through the same gain equations for each term but combined as the square root of the sum of squared contributing elements. See the OA-12 Noise Analysis for Comlinear Amplifiers application report for a full discussion of noise calculations for current-feedback amplifiers.