Ziyad Altarawneh and Mutaz Al-Tarawneh Jordanian Journal of Computers and Information Technology (JJCIT), Vol. 07, No. 02, June 2021. Abstract : The development of nano-scale Quantum-dot Cellular Automata (QCA) has been driven by the immense need for high-performance and energy-efficient computational systems. In this paper, 2- and 3-input QCA-based asynchronous arbiter designs are presented and investigated. A number of 2-input arbiter structures are introduced and compared with their majority-based counterpart. Simulation results show that the proposed structures outperform the majority-based arbiters in terms of number of cells, area and energy dissipation while achieving similar arbitration functionality. In addition, efficient resource utilization is obtained by configuring the proposed structures to consider the input priorities when making arbitration decision. Moreover, two 3-input arbiters are designed based on the proposed 2-input structures and proved to achieve the intended arbitration functionality. The proposed 3-input structures have surpassed their majority-based counterpart. Ultimately, the proposed arbiter designs can serve as basic building blocks in handling resource sharing in system-on-chip (SoC).   KEYWORDS :QCA, System-on-chip, Arbiter, Resource utilization.