Temperature compensated high precision current source

A high precision current source, comprising:

• a) a control means connected to a voltage supply for producing a control signal;
• b) a first current generating part having a first current generating means for generating a first current which is proportional to absolute temperature in response to the control signal from the control means and a first current transferring means for transferring the first current to a common node, wherein the first current generating means including:
• first and second NMOS transistors, each of which has a drain connected to the first current transferring means and a gate commonly connected to the first current transferring means;
• a first bipolar junction transistor which has an emitter serially connected to a source of the first NMOS transistor, and a base and a collector connected to a ground voltage level, respectively;
• a first resistor serially connected to a source of the second NMOS transistor;
• and
• a second bipolar junction transistor which has an emitter serially connected to the first resistor, and a base and a collector connected to the ground voltage level, respectively;
• c) a second current generating means for generating a second current which is inversely proportional to absolute temperature in response to the control signal from the control means;
• d) a second current transferring means for transferring the second current to the common node, wherein the common node adds the first and second currents and generates a third current which is compensated for a current variation caused by a temperature variation at the first and second current generating means;
• and
• e) an output means connected to the common node for receiving the third current from the common node and generating a constant current.