US Patent 9998305 Multi-PAM output driver with distortion compensation

An integrated circuit device includes an output driver having a data signal terminal, logic circuitry, and a driver circuit coupled to the logic circuitry and data signal terminal. The driver circuit is configured to drive a signal corresponding to a symbol onto the data signal terminal, wherein the symbol is an N-bit symbol, having one of 2N predefined values, N is an integer greater than 1, and the signal corresponding to the symbol has one of 2N signal levels. The driver circuit includes first, second and third driver sub-circuits, each driven by an input corresponding to one or more bits of the N-bit symbol, wherein the second and third driver sub-circuits are weighted, relative to the first driver sub-circuit, to reduce gds distortion in the signal.