7.3.2 Input Bias Current Cancellation

The input stage base current of the OPA4277-SP is internally compensated with an equal and opposite cancellation circuit. The resulting input bias current is the difference between the input stage base current and the cancellation current. This residual input bias current can be positive or negative.

When the bias current is canceled in this manner, the input bias current and input offset current are approximately the same magnitude. As a result, it is not necessary to use a bias current cancellation resistor, as is often done with other operational amplifiers (see Figure 21). A resistor added to cancel input bias current errors may actually increase offset voltage and noise.

Figure 21. Input Bias Current Cancellation