An active diode circuit comprising: an active diode (300, 350), the active diode (300, 350) comprising an anode terminal (305, 355), a cathode terminal (307, 357) and a control terminal (309, 359); a control circuit (500, 525, 600, 650) configured to generate a control current ( I c) of the active diode(300, 350) on the control terminal (309, 359) proportional to the diode current ( I D) of the active diode (300, 350), characterised in that the control circuit (500, 525, 600, 650) comprises a current mirror circuit (503, 505, 529, 531) connected across the anode (305, 355) or cathode (307, 357) and the control terminal (309, 359) and configured to control the diode voltage ( V D) of the active diode (300, 350) below a first predetermined threshold, and in that the active diode (300, 350) comprises: a first MOSFET (301, 351) of a first conductivity type; and a second MOSFET (303, 353) of the first conductivity type, wherein the source of the first and second MOSFETs (301, 351, 303, 353) are connected to form one of the anode and cathode of the active diode (300, 350), the gate and drain of the second MOSFET (303, 353) is connected to the gate of the first MOSFET (301, 351), the drain of the first MOSFET (301, 351) form the other one of the anode and cathode of the active diode (300, 350), and the gate of the second MOSFET (303, 353) forms the control terminal (309, 359) of the active diode (300, 350). an active diode (300, 350), the active diode (300, 350) comprising an anode terminal (305, 355), a cathode terminal (307, 357) and a control terminal (309, 359); a control circuit (500, 525, 600, 650) configured to generate a control current ( I c) of the active diode(300, 350) on the control terminal (309, 359) proportional to the diode current ( I D) of the active diode (300, 350), characterised in that the control circuit (500, 525, 600, 650) comprises a current mirror circuit (503, 505, 529, 531) connected across the anode (305, 355) or cathode (307, 357) and the control terminal (309, 359) and configured to control the diode voltage ( V D) of the active diode (300, 350) below a first predetermined threshold, and in that the active diode (300, 350) comprises: a first MOSFET (301, 351) of a first conductivity type; and a second MOSFET (303, 353) of the first conductivity type, wherein the source of the first and second MOSFETs (301, 351, 303, 353) are connected to form one of the anode and cathode of the active diode (300, 350), the gate and drain of the second MOSFET (303, 353) is connected to the gate of the first MOSFET (301, 351), the drain of the first MOSFET (301, 351) form the other one of the anode and cathode of the active diode (300, 350), and the gate of the second MOSFET (303, 353) forms the control terminal (309, 359) of the active diode (300, 350). a first MOSFET (301, 351) of a first conductivity type; and a second MOSFET (303, 353) of the first conductivity type, wherein the source of the first and second MOSFETs (301, 351, 303, 353) are connected to form one of the anode and cathode of the active diode (300, 350), the gate and drain of the second MOSFET (303, 353) is connected to the gate of the first MOSFET (301, 351), the drain of the first MOSFET (301, 351) form the other one of the anode and cathode of the active diode (300, 350), and the gate of the second MOSFET (303, 353) forms the control terminal (309, 359) of the active diode (300, 350).