A wireless communication system with a maximum data rate of 100 Gbit s−1 over 20 m is demonstrated using a carrier frequency of 237.5 GHz. The photonic schemes used to generate the signal carrier and local oscillator are described, as is the fast photodetector used as a mixer for data extraction.

Wireless sub-THz communication system with high data rate

Infrared (2–12 μm) solid-state laser sources: a review

The wavelength range around 2 μm which is covered by the laser systems described in this chapter is part of the so called “eye safe” wavelength region which begins at about 1.4 μm. Laser systems that operate in this region offer exceptional advantages for free space applications compared to conventional systems that operate at shorter wavelengths. This gives them a great market potential for the use in LIDAR and gas sensing systems and for direct optical communication applications. The favourable absorption in water makes such lasers also very useful for medical applications. As it can be seen in figure 1, there is a strong absorption peak near 2 μm which reduces the penetration depth of this wavelength in tissue to a few hundred μm.

/pdf/2-um-laser-sources-and-their-possible-applications-1d92yqfuna.pdf

2 µm Laser Sources and Their Possible Applications

This paper critically investigates the advantages and limitations of the current-transient methods used for the study of the deep levels in GaN-based high-electron mobility transistors (HEMTs), by evaluating how the procedures adopted for measurement and data analysis can influence the results of the investigation. The article is divided in two parts within Part I. 1) We analyze how the choice of the measurement and analysis parameters (such as the voltage levels used to induce the trapping phenomena and monitor the current transients, the duration of the filling pulses, and the method used for the extrapolation of the time constants of the capture/emission processes) can influence the results of the drain current transient investigation and can provide information on the location of the trap levels responsible for current collapse. 2) We present a database of defects described in more than 60 papers on GaN technology, which can be used to extract information on the nature and origin of the trap levels responsible for current collapse in AlGaN/GaN HEMTs. Within Part II, we investigate how self-heating can modify the results of drain current transient measurements on the basis of combined experimental activity and device simulation.

Deep-Level Characterization in GaN HEMTs-Part I: Advantages and Limitations of Drain Current Transient Measurements

We present an overview of solid-state integrated circuit amplifiers approaching terahertz frequencies based on the latest device technologies which have emerged in the past several years. Highlights include the best reported data from heterojunction bipolar transistor (HBT) circuits, high electron mobility transistor (HEMT) circuits, and metamorphic HEMT (mHEMT) amplifier circuits. We discuss packaging techniques for the various technologies in waveguide modules and describe the best reported noise figures measured in these technologies. A consequence of THz transistors, namely ultra-low-noise at cryogenic temperatures, will be explored and results presented. We also present a short review of power amplifier technologies for the THz regime. Finally, we discuss emerging materials for THz amplifiers into the next decade.

/pdf/an-overview-of-solid-state-integrated-circuit-amplifiers-in-375xqeot7y.pdf

An Overview of Solid-State Integrated Circuit Amplifiers in the Submillimeter-Wave and THz Regime

AlGaN/GaN HEMTs on various substrates have raised a lot of interest for the application in future high-efficiency base station systems for next generation mobile communication, currently dominated by LDMOS technology. Using GaN technology in a transmitter, infrastructure equipment manufacturers will benefit from major improvements in system performance and flexibility. AlGaN/GaN HEMTs enable innovative circuit concepts and transceiver architecture (e.g. switch mode power amplifiers, SMPA) with high efficiency and high operating bias. However, besides performance it will be crucial to match or even exceed the device reliability of other technologies in order to be competitive. To meet this goal, it is vital to optimize epitaxial growth as well as process technology.

High-efficiency, high-breakdown AlGaN/GaN HEMTs with lifetimes beyond 20 years

Gallium Nitride is a key technology with high system impact for European industries for communication-, military-, and space-applications. This paper reviews the recent technical development activities of III-Nitride devices for RF-applications in Europe. After the completion of several significant research projects, the technical status is reviewed based on recent examples relevant to the state-of-the-art in Europe. Further, a European perspective for the industrialization and exploitation of this technology will be discussed.

Gallium Nitride RF-devices: An overview on the development activities in Europe

In this paper, we report the achieved performance of devices and integrated circuits (ICs) using a manufacturable InP DHBT-based technology High speed MBE grown InGaAs/InP DHBTs with an effective emitter junction area of 48 /spl mu/m/sup 2/ exhibited peak f/sub T/ and f/sub MAX/ values of 265 and 305 GHz, respectively, at a collector current density of 375 mA//spl mu/m/sup 2/ Using this technology, a set of basic analog and digital IC building blocks, including lumped amplifiers, voltage controlled oscillators, multiplexers and demultiplexers, suitable for operation at 40 Gb/s and beyond, have been successfully designed and fabricated

http://ieeexplore.ieee.org/iel5/10684/34306/01637169.pdf

InP DHBT-based IC technology for high-speed data communications

We have measured and analyzed the room-temperature capacitance-voltage (C-V) characteristics of In0.35Ga0.65As/GaAs MQW laser structures with different doping levels in the active region. Average doping densities in the well-barrier regions were directly extracted from the as- measured carrier profiles. A model for he C-V measurement, including the self-consistent solution of Poisson and Schroedinger equations, was developed. The carrier profiles obtained from the simulated C-V characteristics do not correspond to the free carrier profiles since the local charge neutrality hypothesis does not hold for QW structures. Thus, the true carrier distribution can only be determined from a full quantum-mechanical simulation of the laser structure. We have determined, form the comparison between experimental and simulated profiles, a conduction band offset (Delta) Ec/(Delta) Eg of 0.81. We have also applied C-V measurements to samples with interdiffused QWs, and obtained the characteristic interdiffusion length.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Characterization and modeling of InGaAs/GaAs multiple quantum well lasers by capacitance-voltage measurements

A two-stage high-power amplifier MMIC was realized with a chip size of 4.5 mm /spl times/ 3 mm operating between 8 GHz and 10 GHz based on a fully integrated microstrip AlGaN/GaN HEMT technology on s.i. SiC substrate. The MMIC device delivers a maximum pulsed output power of 8.9 W (39.5 dBm) at 8.5 GHz at V/sub DS/ = 31 V, 10 % duty cycle, and more than 6 dB gain compression level, and features a linear gain in excess of 20 dB.

Michael Mikulla

Papers

High-efficiency, high-breakdown AlGaN/GaN HEMTs with lifetimes beyond 20 years

Gallium Nitride RF-devices: An overview on the development activities in Europe

InP DHBT-based IC technology for high-speed data communications

Characterization and modeling of InGaAs/GaAs multiple quantum well lasers by capacitance-voltage measurements

A microstrip X-band AlGaN/GaN power amplifier MMIC on s.i. SiC substrate