The primary use case of the input common-mode control loop is in differential transimpedance amplifier applications where two photodiodes are excited by a differential input. Any ambient light that is incident on both photodiodes will produce a DC offset current which is subsequently rejected by the input common-mode loop. The input common-mode loop enables the use of very high feedback resistors to amplify the differential photodiode current while simultaneously rejecting common-mode currents. Disabling the input common-mode loop allows the common-mode current to flow through the feedback resistors thereby reducing the effective output swing for the differential signal component. The THS4567 device can reject sourcing or sinking photodiode currents.

The high impedance CMOS inputs of the THS4567 device minimizes the amplifiers input current noise enabling the use of very high transimpedance gains (>100 kΩ), while the low input voltage noise maximizes the system signal-to-noise ratio (SNR). The high gain bandwidth product of the THS4567 device allows it be used as a single-stage differential transimpedance amplifier while driving a high performance ADC driver.