Once the desired gain is determined, choose a value for RI or RF. [Subscripts should be fixed in the accompanying figures and equations also.] Choosing a value in the kilohm range is desirable because the amplifier circuit uses currents in the milliampere range. This ensures the part does not draw too much current. This example uses 10 kΩ for RI which means 36 kΩ is used for RF. This was determined by Equation 3.