Current-detecting circuit

A current-detecting circuit comprising:

• a current mirror circuit including first and second transistors of a first polarity, an emitter of said first transistor being connected to an emitter of said second transistor, said first transistor having a vase and collector connected to each other, said current mirror circuit having an input-to-output current ratio of M:1 wherein M is a real number greater than or equal to 1;
• a power current source connected to a node to which said emitters of said first and second transistors are commonly connected;
• a third transistor of a second polarity, said third transistor having a collector and a base directly connected to said collector of said first transistor;
• a fourth transistor of said second polarity, said fourth transistor having a collector connected to a collector of said second transistor, and a base connected to said base of said third transistor, said fourth transistor having an emitter area N times wider than an area of an emitter of said third transistor wherein N is a real number greater than or equal to 1;
• a current-detecting resistor element connected between said emitters of said third and fourth transistors;
• and
• a fifth transistor of said second polarity, said fifth transistor having a base connected to a node to which said collectors of said second and fourth transistors are commonly connected.