A Terahertz Integrated High-Power CMOS Radiator with Distributed Antenna

Description

The terahertz (THz) radiation, known as T-ray, is defined as the electromagnetic waveswith frequency from 0.3THz to 3THz, which locates in the transition region betweenmicrowave and infrared in the electromagnetic spectrum. As early as 2004, THztechnology was recognized as “one of the ten emerging technologies that will change theworld”, owing to its promising applications in numerous areas including security,biomedicine, communication, astronomy, etc. Imaging, spectroscopy and high-speedwireless communications using T-rays are some application examples receiving a greatdeal of research interest and development efforts. It is projected that the THz marketwill grow at a compound annual growth rate of 26% and reach over US$380 million by2022.However, there have been major fundamental challenges in implementing THz systemsbecause the frequency is either too low or too high to employ traditional optical orelectronic approaches, respectively. Despite of many other difficulties, it’s commonlyagreed that the lack of appropriate radiating sources is the critical bottleneck holding upthe progress of THz technologies. So far, most existing THz radiators are implementedusing optics, quantum cascade lasers, or compound III-V semiconductor processes, whichare expensive, bulky and of low integration level. Advanced nm-scale CMOS would be apotential solution for form factor and cost reduction, but the transistors’ cut-offfrequency is lower than 300GHz such that neither fundamental oscillation nor poweramplification can be employed for an efficient THz signal generation. Recently,frequency multiplication and harmonic oscillation techniques were proposed, boosting upthe frequency to exceed 300GHz. However, theoretically these techniques suffer fromsevere loss due to the ultralow frequency conversion efficiency, resulting in limitedoutput power. Moreover, for the signal radiation, the on-chip antennas are of lowefficiency and low gain owing to the lossy silicon substrate. Off-chip antennasthemselves feature better performance but their physical contacts with the chip wouldseverely deteriorate the system performance. Consequently, state-of-the-art CMOSradiators can only achieve limited performance in terms of output power, EIRP(equivalent isotropic radiated power) and DC-to-THz power conversion efficiency.This project aims to explore new THz techniques including varactor-less frequencytuning for signal generators, distributed structure for antennas and hierarchical powercombining for system integration. A CMOS radiator suitable for many THz applicationswill be implemented, targeting at generating 320GHz T-rays with 0-dBm output power,12-dBm EIRP and 0.3% power efficiency.