The LOG200 includes an IBIAS current output feature that can be used to bias a photodiode with a voltage that is proportional to the photocurrent. The current from the IBIAS pin is nominally 1.1 times the input current of the I1 pin. When an R_BIAS resistance is placed in parallel with the photodiode, 1.0 times the input current is drawn through the photodiode and the remaining 0.1 times the input current flows through R_BIAS. This configuration establishes a bias voltage across that resistance. As the anode end of the photodiode (connected to the I1 input) is held at V_CM, the cathode voltage effectively rises by 0.1 × R_BIAS × I₁, thus providing a current-dependent reverse bias voltage for the photodiode.

This feature creates very small bias voltages for applications with low photodiode currents, reducing the dark current of the photodiode. In applications with high photodiode currents (which often require larger photodiodes), higher reverse-bias voltages are developed, thus reducing the effective capacitance of the photodiode and increasing the effective device bandwidth. If this feature is not used, float the IBIAS pin.