The LOG200 converts current into voltage using an advanced, high-speed amplifier architecture. By dynamically controlling the amplifier open-loop gain, the LOG200 achieves transient response from low-to-high current and high-to-low current measurements significantly faster than previous-generation logarithmic amplifiers.

The LOG200 features two current inputs, I1 and I2. The I1 input is optimized for speed, facilitating the excellent transient response of the device to changes in the current to be measured. The I2 input is optimized for precision and accuracy, intended for use with a current reference such as the onboard 1-μA reference. If an external current in excess of 100 μA is used for I2, implementation of a snubber network can improve device stability.

The effective capacitance at a current input pin establishes the effective bandwidth of the corresponding feedback loop, and thus the effective device bandwidth. Photodiode capacitance and system parasitics both play a role and must be considered for stability and transient performance analyses.