CMOS Operational amplifier with reduced power dissipation

An operational amplifier comprising:

• a first and a second conductor, said first conductor connected to a first voltage source and said second conductor connected to a second voltage source;
• a bias section connected between said pair of conductors, said bias section having an output terminal;
• a differential amplifier section, connected between said first and second conductors including a constant current element connected to said output terminal of said bias section, said differential amplifier section including an input section for receiving positive and negative input signals and an output terminal;
• a Class A-B output section connected between said first and second conductors, said output section comprising a pair of complementary MOS transistors connected in series each transistor including a control terminal, and said output section having an output terminal for providing an output signal related to said input signals;
• first means for connecting said output terminal of said differential amplifier directly to the control terminal of one of said transistors of said output section;
• a level shift section connected between said pair of conductors, said level shift section having an output terminal, wherein said level shift section comprises three MOS transistors connected in series between said first and second conductors, each of said three MOS transistors having a gate electrode and one of said three MOS transistors having its gate electrode connected to said differential amplifier output terminal by a second means for connecting;
• third means for connecting said level shift section output terminal to the control terminal of the other transistor of said output section;
• and
• a supplementary output stage having an output terminal, said supplementary output stage comprising a bipolar transistor having its base connected to said output node of said output stage,
• whereby said supplementary output stage provides a relatively low output impedance on said output terminal.