A current-feedback op amp such as the THS6212 provides exceptional bandwidth in high gains, giving fast pulse settling but only moderate dc accuracy. The Electrical Characteristics tables describe an input offset voltage that is comparable to high-speed, voltage-feedback amplifiers; however, the two input bias currents are somewhat higher and are unmatched. Although bias current cancellation techniques are very effective with most voltage-feedback op amps, these techniques do not generally reduce the output dc offset for wideband current-feedback op amps. Because the two input bias currents are unrelated in both magnitude and polarity, matching the input source impedance to reduce error contribution to the output is ineffective. Evaluating the configuration of Figure 7-1, using a typical condition at 25°C input offset voltage and the two input bias currents, gives a typical output offset range equal to Equation 4:

Equation 4.

where

• NG = noninverting signal gain