In this paper, we propose a novel extension of Bus-Invert coding to handle 4-level pulse amplitude modulated (PAM-4) signals. A generalized mathematical model for energy consumption and energy dissipation for PAM-4 signals is presented and a family of coding schemes are developed that can reduce the average power consumption and dissipation by up to 54% compared to un-coded PAM-4 buses. This technique is attractive for high-speed data transmission systems that employ PAM-4 signals on general high capacitance buses such as global wires, off-chip buses, I/O and backplanes.
['Fakhrul Zaman Rokhani', 'Gerald E. Sobelman']
Low-Power Bus Transform Coding for Multilevel Signals