2016 Events

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Far-field wireless power transfer (WPT) has been reconsidered in recent years as practical means to transfer power from outer space where satellites collect solar power with high efficiency using photovoltaic technology and then convert the power to microwaves for beaming to antenna farms at specific locations on earth. Conventional antennas have been the traditional microwaves transducers used for WPT applications. Almost all antennas that were considered for WPT applications were designed in the first place for communication applications where traditional antenna parameters such as gain, directivity and efficiency were considered the most critical. For WPT applications, however, the primary concern is to collect as much power as possible per footprint, based on specific polarization and incident angle.

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Optical links 1 – 100 metres in length require low cost, low power consumption and small size. Vertical cavity surface emitting lasers (VCSELs) can be arrayed inexpensively and can be directly modulated, avoiding the need for separate optical modulator components. VCSELs operating at 850nm coupled to multimode fiber offer a compact and inexpensive optoelectronic assembly, and are predominant for short reach optical communication. The key challenge for the transmitter circuit in such systems is to modulate single-ended VCSEL currents up to about 10mA at 25+Gb/s while maintaining bias voltages of approximately 2V across the VCSELs. At the receiver, a key challenge is to provide adequate sensitivity using photodiodes with wide (50um) aperture and, hence, large capacitance. Current commercial transceiver circuits are realized in SiGe BiCMOS, which is advantageous at both the transmitter and receiver, but CMOS offers the potential for higher levels of integration and lower power consumption. Our research efforts on low-power CMOS VCSEL drivers and optical receivers will be presented, including several 65nm CMOS designs.