US Patent 7723975 Current detecting circuit

Indirect detection of current using a current mirror circuit is performed with good accuracy, with a small sized circuit. In a current detection circuit, a current detection current mirror circuit includes an output current transistor which supplies an output current, and a current detection transistor which supplies a detection current proportional to the output current. A compensation current mirror circuit is connected to a current supply side of the current detection current mirror circuit, so as to make a collector voltage of the output current transistor and a collector voltage of the current detection transistor equal. A current detector detects the detection current, to indirectly detect the output current.