US Patent 7456769 Reference voltage generating circuit

A reference voltage generating circuit includes a first capacitor having a first end and a second end; a second capacitor having a third end and a fourth end; a first switch for selectively coupling a predetermined voltage to the first end of the first capacitor; a second switch for selectively coupling the third end of the second capacitor to the first end of the first capacitor; a third switch for selectively coupling the first end of the first capacitor to a reference voltage level; and a fourth switch for selectively coupling the second end of the first capacitor to a reference voltage level; wherein the first capacitor samples the predetermined voltage in a first stage and re-distributes charges to the second capacitor in a second stage.