F type devices are for applications with high currents (above 100µA) or precise time requirements.
These devices use the I-V converter circuit, also known as a transimpedance amplifier. The input current passes through a resistor to develop a voltage according to Ohms law. We use an operational amplifier to ensuring no signal loss through stray resistances.
The voltage output continuously tracks the current input. The bandwidth of the operational amplifier and stray capacitances attenuate very high frequencies. Low-pass filters attenuate frequencies closer to the ADC sample rate.