Current mirror type constant current source circuit having less dependence upon supplied voltage

A current mirror type constant current source circuit comprising:

• a current mirror circuit composed of first and second MOS transistors of a first conduction type connected to form a first current mirror, a source-drain path of said first MOS transistor forming an input current path of said current mirror circuit, and a source-drain path of said second MOS transistor forming an output current path of said current mirror circuit,
• a current source connected between an input end of said input current path of said current mirror circuit and a voltage supply line, and
• a third MOS transistor of said first conduction type having a source and a drain connected to a source and a drain of said first MOS transistor, respectively, a gate of said third MOS transistor being connected to said voltage supply line,
• and wherein said current source includes a second current mirror circuit having fourth and fifth MOS transistors which are of a second conduction type opposite to said first conduction type connected to form a second current mirror, a source-drain path of said fourth MOS transistor forming an output current path of said second current mirror circuit and being connected between said input end of said input current path of said first current mirror circuit and said voltage supply line, and a gate of said fourth MOS transistor being connected to a gate of said fifth MOS transistor, a source-drain path of said fifth MOS transistor forming an input current path of said second current mirror circuit and being connected through a second current source between said high voltage supply line and said ground.