Analysis and implementation of charge recycling for deep sub-micron buses

Charge recycling has been proposed as a strategy to reduce the power dissipation in data buses. Previous work in this area was based on simplified bus models that ignored the coupling between the lines. Here we propose a new charge recycling technique (CRT) appropriate for sub-micron technologies. CRT is analyzed mathematically using a bus energy model that captures the energy loss due to strong line to line capacitive coupling. In theory CRT can result in an energy reduction by a factor of 2. It becomes even more energy efficient when combined with bus invert coding (see Stan, 1997). A circuit has been designed and simulated with all parasitic elements extracted from the layout. Taking into account the circuit energy overhead the net result in energy saving can be up to 32%.