In brief

Abstract

PAGE 800 A relaxation oscillator with no comparator and no reference voltage is presented in work from China. By replacing a conventional comparator with a pseudo-inverter chain it avoids comparator offset effect, achieving low temperature coefficient and ultra-low power consumption. The resulting fully-integrated relaxation oscillator is aimed at energy harvesting applications requiring ultra-low power consumption. PAGE 789 Researchers in China present a terahertz transmit array made using PCB technology. Their proposed approach is low-cost with simple structures and they expect it to reduce the overall cost of THz systems. The device they have demonstrated provides 360° phase coverage with a transmission coefficient better than −3.52 dB at 250 GHz. The oscillator is designed to achieve ultra-low power consumption for use in energy harvesting systems PAGE 797 A team in Japan have developed a vertically-tapered spot-size converter (VT-SSC) using a simpler fabrication process than previously reported InP-based SSCs. The VT core layer was formed by dry etching using the micro-loading effect and the resulting device is very compact at just 200 µm. The team say the compactness and easy fabrication of the VT-SSC mean it can be used to improve the optical coupling loss that occurs during InP photonic integrated circuit assembly. Low-cost PCB techniques were used to manufacture the terahertz transmit array PAGE 814 Work from the UK explores the possibilities of using social media data to map service blackspots in cellular networks. In the example presented, natural language processing techniques have been applied to twitter posts to identify quality of experience complaints and this is combined with the geo-tagging data to identify blackspots and present small-cell deployment recommendations. The simpler manufacture and compact form of the converter will help reduce optical losses incurred during circuit assembly PAGE 810 Researchers in Korea have developed a process that allows dies to align spontaneously on a pad of substrate without the use of die-attach equipment. Their new process uses the under bump metallurgy (UBM) on the back of the chips to improve the die shift issue for fan-out wafer-level packaging, reducing maximum die shift to less than 1 µm. They believe this approach could also be applied to panel-level fan-out packages. Natural language processing of tweets is used to identify quality of experience complaints in mobile networks and map service blackspots The new approach uses UBM on the reverse of the chip to reduce die shift during manufacture