It is a current to voltage converter. the ratio of the converted voltage to the input current is notated as the K-factor, which indicated that the converter may amplify the signal as well.

The reason for study a I-V converter is due to the experiment’s needs, that we have a current output but we want to know the size of the current without affecting the circuit.

A simple I-V converter is made by 1 single resistance. When a current passes the resistance, a voltage is built across it. If we measure the voltage with an infinite load voltage meter, then no current will go to the voltmeter and system is unaffected. In this case, the resistance of the resister is the K-factor.

However, we normally deal with an AC signal, which is oscillating with frequency.

If the converter amplify the AC signal, it has capacitance and reactance (impedance) depends on input frequency.  So, we have to choose a correct range of working frequency of the converter.