Transmit pre-emphasis for high-speed time-division-multiplexed serial-link transceiver

Time Division Multiplexing (TDM) must be employed in multi-GSa/s transceivers in order to overcome onchip clock frequency limitations. This paper describes a transmit pre-emphasis filter for a multi-level transceiver making use of TDM. The possible applications of such a transceiver include serial links and chip-to-chip communication. The requirement of very low probability of error in the absence of coding, and the need for an adaptive solution impose a peak transmit power constraint. The TDM system is mapped to a Multiple-Input-Multiple-Output (MIMO) system, and the noise sources are analyzed. The design of the pre-emphasis filter is shown to be a non-convex optimization problem, whose optimal solution is very difficult to obtain. Still, sub-optimal solutions are derived in closed form and adaptive implementations are described. Simulation results using parameters obtained from an experimental testbed indicate that these sub-optimal solutions actually achieve very good performance.