Multiport memories are increasingly used in smart-phones, multimode handsets, multiprocessor systems, network processors, graphics chips, and other high performance electronic devices [1,2,4,8]. This paper presents a fully distributed software solution to the arbitration problem in multiport memory systems. Our solution is simple, efficient, and assures LRU fairness.
We fabricated surface acoustic wave (SAW) filters on three nominally 2-µm-thick undoped GaN layers grown on (0001) sapphire substrates. We extracted SAW velocities for frequencies of the central and subsidiary peaks in the |S21| spectra by applying the δ-function model. We further obtained thicknesses of respective GaN layers by analysing their reflectivity spectra, and established the SAW velocity dispersion. The respective dispersion data were found to lie close to each other, which suggests that characteristics of GaN-based SAW devices can be designed with improved accuracy.
We evaluated the possibility of monolithic integration of electron devices and surface acoustic wave (SAW) devices on GaN. We removed top n+ GaN layers of n+ GaN/unintentionally-doped GaN structures by inductively coupled plasma (ICP) etching and fabricated SAW filters on the exposed unintentionally doped GaN layers. We found that the device characteristics are almost the same as those of devices fabricated on as-grown GaN layers, although the surface morphology of GaN layers is degraded due to the ICP etching. The results indicate that SAW devices and electron devices can be monolithically integrated on GaN-based semiconductor structures.
We investigated the electromagnetic compatibility of 155Mb/s optical transceiver module. The margin of 3.4dB for radiated emission and the penalty of 3.0dB for radiation susceptibility were measured for the device and the effect of metallic shielding plate on performance enhancement was also evaluated.