This circuit produces an output voltage, Vo, that is proportional to the input current, Is. The output voltage is measured using a voltmeter. The input current is the current of the current source. The constant of proportionality is equivalent resistance of the parallel resistors. The value of the equivalent resistance is determined by the resistances, R1 and R2, of the two resistors that comprise the parallel resistors.
The equivalent resistance, Req, of the parallel resistors is given by
The output voltage is related to the input current by
The design equations
show how to select values of R1 and R2 to achieve a specified value of equivalent resistance.