A 225 MHz resonant clocked ASIC chip

We have recently designed, fabricated, and successfully tested an experimental chip that validates a novel method for reducing clock dissipation through energy recovery. Our approach includes a single-phase sinusoidal clock signal, an L-C resonant sinusoidal clock generator, and an energy recovering flip-flop. Our chip comprises a dual-mode ASIC with two independent clock systems, one conventional and one energy recovering, and was fabricated in a 0.25 μm bulk CMOS process. The ASIC computes a pipelined discrete wavelet transform with self-test and contains over 3500 gates. We have verified correct functionality and obtained power measurements in both modes of operation for frequencies up to 225 MHz. In the energy recovering mode, our power measurements account for all of the dissipation factors, including the operation of the integrated resonant clock generator, and show a net energy savings over the conventional mode of operation. For example, at 115 MHz, measured dissipation is between 60% and 75% of the conventional mode, depending on primary input activity. To our knowledge, this is the first ever published account of a direct experimentally-measured comparison between a complete energy recovering ASIC chip and its conventional implementation correctly operating in silicon at frequencies exceeding 100 MHz.