Reference current source

A reference current source, comprising:

• a reference voltage circuit, generating a reference voltage;
• a buffer amplifier including an output terminal and a non-inverting input terminal connecting to the reference voltage circuit to receive the reference voltage;
• a voltage division circuit, connecting to the output terminal of the buffer amplifier and dividing the reference voltage and outputting a divided voltage;
• and
• an output MOS transistor, supplying a reference current in response to the divided voltage being applied to a gate terminal,
• wherein the reference voltage circuit comprises:
• a depletion type MOS transistor;
• and
• an enhancement type MOS transistor, having same conductivity type and impurity concentration as a channel of the depletion type MOS transistor and a different Fermi level from a gate electrode of the depletion type MOS transistor,
• wherein the voltage division circuit outputs the divided voltage to a gate terminal of the output MOS transistor, wherein the divided voltage is within a voltage range which is above OV and lower than a cross point at which a gate voltage-drain current characteristic of the output MOS transistor does not depend on temperature in order that a positive temperature coefficient of a drain current of the output MOS transistor cancels a negative temperature coefficient of the reference voltage, wherein the divided voltage cancels a temperature characteristic of the reference voltage so that the drain current of the output MOS transistor does not fluctuate with temperature.