Design of Pass Transistor-Based Low-Power Approximate Adders for DSP Application

This paper presents a low-power, and energy-efficient pass transistor-based full adder, along with two other approximate adders sharing the same constructional pattern. Initially, three conventional full adders are analyzed, namely the mirror adder, XOR and XNOR-based adder circuits. Based on these circuits, a new energy-efficient 12T full adder is designed that consumes much less power compared to conventional full adder circuits. The design is implemented in 45nm technology with a +0.8 V supply voltage. Schematic simulations in Cadence Virtuoso tools showed a 60%-85% improvement in power consumption compared to previously stated conventional adders. Furthermore, the research extends to the development of two innovative approximate adder designs that demonstrate remarkable improvements in power efficiency while maintaining an acceptable level of accuracy. Finally, a comparative analysis of conventional approximate full adders proved our proposed approximate adders outperformed existing ones, in terms of power consumption, power delay product, and bit error rate.