Patent ID: 7362104

Claim:
A current measuring apparatus for measuring a power supply current received by an electronic device comprising: a first current supplying unit for outputting a first current which is a part of the power supply current; a capacitor of device side for smoothing the power supply current; a smoothing capacitor for smoothing the first current output by said first current supplying unit connected on a path between an output of the first current supplying unit and a point of connection with said capacitor of device side, wherein an electrostatic capacity of said capacitor of device side is smaller than that of said smoothing capacitor and one end of said capacitor of device side is connected with the electronic device; a switch for making the first current flow from said smoothing capacitor to said capacitor of device side in case of being ON; a second current supplying unit for outputting a second current which is smaller than the first current to said capacitor of device side via a path parallel to said switch, wherein the path parallel to said switch is free of connection to any capacitor between an output of the second current supplying unit and a point of connection with said capacitor of device side; and a power supply current acquiring unit for acquiring the power supply current on the basis of the second current output by said second current supplying unit.