Constant current circuit

A constant current circuit, comprising:

• a first diode;
• a second diode;
• a resistor coupled to a first terminal of the second diode;
• first and second transistors of a first conductivity type, control gates of the first and second transistors being connected to each other, the first transistor being coupled to the first diode, the second transistor being coupled to a second terminal of the resistor;
• third and fourth transistors of a second conductivity type, control gates of the third and fourth transistors being connected to each other, the third transistor being coupled to the first transistor, the fourth transistor being coupled to the second transistor;
• a variable resistance element coupled between a first crossing node of the first diode and the first transistor and a second crossing node of the resistor and the second diode;
• and
• a feedback unit which controls to reduce a resistance value of the variable resistance element when a current obtained by the third and fourth transistors becomes larger, in order to reduce a voltage potential difference at the first crossing node and the second crossing node.