Abstract-A compact dual-band annular-ring slot antenna (ARSA) is proposed for use in 2.4/5 GHz wireless local-area networks (WLANs). With a meandered grounded strip embedded in the ring slot, three resonant modes were excited. With a pair of notches properly etched in the inner circular patch, the third resonant band was sufficiently lowered so that the second and third resonant bands are combined to form a wider upper operating band. If scaled to the same lower operating-band center frequency, the proposed ARSA measures only 53.6% the area of a conventional microstrip-line-fed ARSA. Measured and simulated results were found to agree reasonably well with each other.

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Although a lot of research efforts have been made in the minimization of the total power consumption caused by the clock tree, no attention has been paid to the minimization of the peak current caused by the clock tree. In this paper, we propose an opposite-phase scheme for peak current reduction. Our basic idea is to divide the clock buffers at each level of the clock tree into two sets: an half of clock buffers operate at the same phase of the clock source, and another half of clock buffers operate at the opposite phase of the clock source. Consequently, our approach can reduce the peak current of the clock tree nearly 50%. Experimental data consistently show that our approach works well in practice.