Current source responsive to supply voltage variations

A current source comprising:

• a diode element having an anode and a cathode;
• a resistive element having a first end connected to a first voltage source and a second end connected to said cathode of said diode element;
• a first transistor having a drain coupled to said anode of said diode, a source coupled to a second voltage source, and a gate coupled to said drain;
• a second transistor having a gate coupled to said gate of said first transistor and having a source coupled to said second voltage source;
• a third transistor having a drain and a gate coupled together and to a drain of said second transistor and having a source coupled to said first voltage source;
• a fourth transistor having a gate coupled to said gate of said third transistor and having a source coupled to said first voltage source;
• a fifth transistor having a gate and a drain coupled together and to a drain of said fourth transistor and having a source coupled to said second voltage source;
• and
• a sixth transistor having a source coupled to said second voltage source, a gate coupled to said gate of said fifth transistor, and a drain coupled to an input stage of a circuit.