A review of the theory, technology, and practice of RF coils for small-animal MRI is presented that includes a brief overview of MR S/N analysis and discussions of the various coils commonly used in small-animal MR – surface coils, linear volume coils, birdcages, and their derivatives. The scope is limited to mid-range coils – coils where the product (fd) of the frequency f and the coil diamete...

Power density in active devices is increasing according to the demands of transistor users. Applications in commercial wireless, avionics, broadcast, industrial, and medical systems are pushing the envelope for solid-state power, with growing requirements for higher output power levels from fewer output-stage devices. At Freescale Semiconductor, supplying high-performance radio frequency (RF) a...

Continued research into the development of III–V high-electron mobility transistors (HEMTs), specifically the minimization of the device gate length, has yielded the fastest performance reported for any three terminal devices to date. In addition, more recent research has begun to focus on reducing the parasitic device elements such as access resistance and gate fringing capacitance, which beco...

We present the design and measured results for a 60 GHz double balanced sub-harmonic MMIC mixer fabricated using the TRW 0.15μm gate length GaAs pHEMT foundry process. The sub-harmonic mixer architecture eliminates the need for costly mm-wave sources that are usually required with conventional fundamental frequency mixers. The mixer has been integrated into a coaxial package and a measured conv...

Communication systems today comprise the major use of GaAs technology with the highest volumes found in the cellular handset front-end. Here, heterojunction bipolar transistor (HBT) power amplifiers (PA) and Pseudomorphic High Electron Mobility Transistor (PHEMT) switches enjoy a comfortable market share. In this environment, the demands of production design require a robust CAD system with acc...

This work has as main objective the integration of planar Gunn diodes and high electron mobility transistors (HEMTs) on the same chip for the realisation of high-power oscillators in the millimeter-wave regime. By integrating the two devices, we can reinforce the high frequency oscillations generated by the diode using a transistor-based amplifier. The integration of the planar Gunn diode and t...

The firstly commercialized millimeter-wave application was the automotive radar, which appeared nearly 10 years ago, for driving safety support. The market size has been growing year by year and is expected to reach a level of around five million units per year in 2016. With the progress in popularity, the radar has been expected to spread even to general cars, therefore, development of lowcost...

A new solution for the implementation of a HEMT negative current source is presented. The topology can be also profitably employed as a current mirror and as an active load in high-gain MMICs voltage amplifiers. A small-signal model of the proposed circuit is developed which allows to find accurate expressions for the required transfer functions (i.e., the output impedance of the current source...

This paper demonstrates the viability of wafer-level methods as a means of evaluating device reliability using special reliability test structures and process control monitors (PCM). The results presented illustrate how this methodology can be employed to rapidly and effectively assess the impact of process or material changes on over-all reliability. The wafer-level methodology provides a quic...

We demonstrate vertically and laterally scaled GaAsSb/InP type-II DHBTs with fT = 670 GHz at 10.3 mA/μm emitter current density and off-state collector-emitter breakdown voltage BVCEO = 3.2 V. Small-signal modeling is used to extract delay terms and to identify material design and device fabrication requirements for next-generation devices with > 1 THz cutoff frequencies. INTRODUCTION InP based...