Low energy MTCMOS with sleep transistor charge recycling

A new circuit technique is proposed in this paper to lower the energy overhead of mode transitions for effective energy reduction with the MTCMOS circuits. The charge stored at the virtual rails and the sleep signal lines are recycled during the active-to-sleep-to-active mode transitions with the proposed technique. Applying the charge recycling MTCMOS circuit technique to a 32-bit Brent-Kung adder reduces the energy overhead due to the mode transitions by up to 12.2% as compared to the conventional MTCMOS circuits. Furthermore, the standby mode power consumption is reduced by up to 92.8% as compared to a standard Brent-Kung adder in a 65 nm CMOS technology.