Current detector circuit

A current detector circuit comprising a first insulating gate transistor for a main element;

• a second insulating gate transistor for a sense element, a current input terminal of which is connected to a current input terminal of said first insulated gate transistor, and a control terminal of which is connected to a control terminal of said first insulated gate transistor, the second insulating gate transistor for sensing part of a main current flowing through said first insulating gate transistor;
• a current detection resistor through which a sense current flowing through said second insulated gate transistor flows;
• a control transistor for detecting a voltage drop across said current detection resistor;
• a constant current circuit, connected to a current output terminal of said first insulated gate transistor and a current output terminal of said second insulated gate transistor, the constant current circuit for setting potentials at said current output terminals of said first and second insulated gate transistors to equal to each other;
• and
• a compensation diode and a current detection resistor element which are inserted in series with each other between an output current path of the constant current circuit and a negative bias terminal.