An Ultra-low Power modified SERF Adder for Implantable Bio-medical Applications

This thesis presents the results of the research, design and implementation of an ultra-low power modified Static Energy Recovery Full-Adder (SERF) adder for implantable bio-medical applications. An extensive analysis of the existing low power 10-Transistor SERF adder revealed signal integrity problems due to threshold-voltage losses. As a solution, an ultra-low power full adder cell is designed by modifying the existing circuit. This modified SERF adder operates at extremely low supply voltages with improved signal strength. It showed a significant reduction in power and latency when analyzed using the NCSU 45nm process library at SS, TT & FF corners. To prove the usefulness of this modified circuit and to present a proof of concept, a 32-bit ripple carry adder was implemented in sub-threshold regime. The obtained results showed significant energy savings when compared to the previous work. Therefore, the modified SERF adder is best suitable for building energy efficient ALU blocks in implantable bio-medical devices.