Various active diode circuits are described. In one example, there is provided an active diode circuit having an active diode and a control circuit. The active diode includes an anode terminal, a cathode terminal and a control terminal. The control circuit is configured to generate a control current of the active diode on the control terminal proportional to the diode current of the active diode. The control circuit is also configured to control the diode voltage of the active diode below a predetermined threshold.