32-bit adders using adiabatic switching for low power IC design

• Main Author: Joseph, Dhannya Mary
• Other Authors: Lau Kim Teen
• Format: Theses and Dissertations
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/54906
• Institution: Nanyang Technological University

This dissertation describes the implementation of 32-bit adders using different adiabatic logic families. Adiabatic switching is a technique of power reduction where the energy taken from the power supply is recycled or reused. The adder is the most commonly used and critical arithmetic operator which determines the throughput of the processor. It is for this reason that the power reduction is shown in 32-bit adders. Three adiabatic logic families are used for comparison in this dissertation- Efficient Charge Recovery Logic (ECRL), Clocked CMOS Adiabatic Logic (CAL) and Complementary Energy Path Adiabatic Logic (CEPAL). Initially inverter circuits were implemented using each of these logic styles and compared with vanilla CMOS in terms of power consumption. Next, I-bit full adder circuits were implemented for each of the adiabatic logic styles and compared with vanilla CMOS. 32-bit adders were then implemented and compared to observe the reduction in power consumption. The adders were also tested to see under what range of voltage and frequency the operation is consistent. All the circuits were realized using 65nm CMOS technology using Cadence Virtuoso. There was a significant reduction in power consumption when adiabatic circuits were used. ECRL circuit eliminates the need for diodes but the power saving is not significant compared to the other logic families (44.5% power saving compared to conventional CMOS). The CEPAL has an edge over the other families because it has the simplest power clock generator circuitry as only a sinusoidal power clock is required. However it requires more number of transistors for its implementation. The power consumption is less than ECRL circuits but more than CAL circuits. When compared with vanilla CMOS a power saving of 67.8% was observed. The maximum energy efficiency, 90% saving over conventional CMOS, is observed for CAL circuits and it can also operate at up to 250MHz at 3V and as low at 1.2V when operated at 50MHz. The CAL circuit requires an additional square wave clock signal which acts as an auxiliary clock, thereby increasing the complexity of the power clock generator.