Energy Recovery from High-Frequency Clocks Using DC-DC Converters

Large digital chips use a significant amount of energy to distribute a multi-GHz clock. By discharging the clock network to ground every cycle, the energy stored in this large capacitor is wasted. Instead, the energy can be recovered using an on-chip DC-DC converter. This paper investigates the integration of two DC-DC converter topologies, boost and buck-boost, with a high-speed clock driver. The high operating frequency significantly shrinks the required size of the L and C components so they can be placed on-chip; typical converters place them off-chip. The clock driver and DC-DC converter are able to share the entire tapered buffer chain, including the widest drive transistors in the final stage. To achieve voltage regulation, the clock duty cycle must be modulated; implying only single-edge-triggered flops should be used. However, this minor drawback is eclipsed by the benefits: by recovering energy from the clock, the output power can actually exceed the additional power needed ...

• Type: Conference
• Year: 2008
• Where: ISVLSI
• Authors: Mehdi Alimadadi, Samad Sheikhaei, Guy Lemieux, Shahriar Mirabbasi, William Dunford, Patrick Palmer
• Keywords: Clock, Clock Driver, DC-DC Converter, ISVLSI 2008, VLSI