Fig. 1. Schematic diagram of the proposed current sensor. I: current to be measured; PD: photodiode; PI: proportional-integral; DDS: direct digital synthesis; RF: radio frequency; I/f: Larmor frequency to I data converter.

Fig. 2. Distribution of the magnetic field in the solenoid, which is simulated with ANSYS. The current is 1 A.

Fig. 3. Measured magnetic field (square) and calculated current (dot) versus actual current.

Fig. 4. Absolute error versus actual current.

Fig. 5. Relative error versus actual current.

Fig. 6. Allan variance of the current sensor data.