Patent ID: 7123529

Claim:
An integrated circuit including a circuit for amplifying a small voltage swing signal into a second signal having a rail-to-rail voltage swing, comprising: a conductor adapted to conduct a first signal having a small voltage swing and a second signal having a rail-to-rail voltage swing; and an amplifier coupled to the conductor, said amplifier operable to amplify said first signal into said second signal, said amplifier including a multiple conduction state field effect transistor (“multi-state FET”) having a source, a drain, and a gate operable to control conduction between said source and said drain, said multi-state FET having a first threshold voltage and a second threshold voltage effective at the same time as said first threshold voltage, said gate operable to control said multi-state FET between multiple operational states including a) an essentially nonconductive state when a gate-source voltage applied between said gate and said source does not exceed said first threshold voltage and does not exceed said second threshold voltage and in which a source-drain current between said source and said drain is at most negligible; b) a first conductive state when said gate-source voltage exceeds said first threshold voltage and does not exceed said second threshold voltage such that said source-drain current has a first operating value; and c) a second conductive state when said gate-source voltage exceeds said first threshold voltage and said second threshold voltage such that said source-drain current has a second operating value at least about ten times larger than said first operating value; wherein said multi-state FET is operable by said gate-source voltage to switch between said essentially nonconductive state, said first conductive state and said second conductive state to perform an operation included in amplifying said first signal into said second signal by said amplifier.