A W-band monolithic downconverter

The design, fabrication, and evaluation of a fully integrated W-band monolithic downconverter based on InGaAs pseudomorphic HEMT technology are presented. The monolithic downconverter consists of a two-stage low-noise amplifier and a single-balanced mixer. The single-balanced mixer has been designed using the HEMT gate Schottky diodes inherent to the process. Measured results of the complete downconverter show conversion gain of 5.5 dB and a double-sideband noise figure of 6.7 dB at 94 GHz. Also presented is the downconverter performance characterized over the -35°C to +65°C temperature range. The downconverter design was a first pass success and has a high circuit yield     

High-power pulsed GaAs double-drift hybrid-read impatt diodes for X-band

Gallium-arsenide double-drift hybrid-Read Impatt diodes have been developed to deliver high peak and average powers in X-band. A peak power output of 35 W with 20% efficiency has been obtained at 8.3 GHz for 20% duty cycle. Peak power output of 32 W with 20% efficiency has been obtained at 8·6 GHz for a 25% duty cycle. Peak power output of 26 W with 21.5% efficiency has been obtained at 8.6. GHz for 33% duty cycle.     

Orientation dependence of n-type GaAs intrinsic avalanche response time

The intrinsic avalanche response time of n-type GaAs has been measured for each of the three principal crystallographic orientations: <100>, <110> and <111>. The experimental response times are compared with theoretical values computed using the most recent ionisation-rate data. The <111> orientation is found to have the shortest response time and the <110> has the longest response time, for a nominal net donor density of 4.5 × 1016 cm?3.     

Ion-implanted p?n junction indium-phosphide impatt diodes

Implantation of beryllium ions into a uniformly doped n-type InP epitaxial layer grown by vapour-phase epitaxy has been utilised to create a p+?n junction for flat-profile single-drift impatt diodes. An r.f. performance comparable to gallium arsenide has been obtained. A c.w. output power of 1.6 W with 11.1% conversion efficiency has been measured at 9.78 GHz and a peak power of 6.1 W with 13.7% efficiency has been measured at 10.8 GHz with 10% duty cycle. The f.m. noise of the c.w. oscillators is comparable to results reported for silicon.     

Autonomous battery management for mobile robots based on risk and gain assessment

Battery management of mobile robots is an issue that has not been a strong focus of attention and is usually addressed by the simple use of battery thresholds. One of the main causes is that no significant method of assessment of risk of battery depletion has yet been proposed. As a result decision of redirection to a charging station is fixed and takes into account neither a dynamic evaluation of the risk of battery depletion nor an evaluation of the gain, defined as the level of mission accomplishment that could be achieved. In this paper we propose a novel method for evaluation of risk of battery depletion for mobile robots. Uncertainties concerning effective battery capacity, current discharge rate and energy required for reaching the station are addressed by the use of probability density functions. This risk assessment will allow replacing the usage of battery threshold by a customizable risk-taking parameter that will be used to define what level of gain is required for balancing a given level of risk. This risk/gain management of battery will guarantee that decision of redirection to the station corresponds to a favorable compromise between risk and level of mission accomplishment. While the proposed approach has been tested using a simulated and real room cleaning robot, it could be applied on a wider range of mobile robots.     

High-performance in W-band monolithic pseudomorphic InGaAsHEMT LNA's and design/analysis methodology

High-performance W-band monolithic one- and two-stage low noise amplifiers (LNAs) based on pseudomorphic InGaAs-GaAs HEMT devices have been developed. The one-stage amplifier has a measured noise figure of 5.1 dB with an associated gain of 7 dB from 92 to 95 GHz, and the two-stage amplifier has a measured small signal gain of 13.3 dB at 94 GHz and 17 dB at 89 GHz with a noise figure of 5.5 dB from 91 to 95 GHz. An eight-stage LNA built by cascading four of these monolithic two-stage LNA chips demonstrates 49 dB gain and 6.5 dB noise figure at 94 GHz. A rigorous analysis procedure was incorporated in the design, including accurate active device modeling and full-wave EM analysis of passive structures. The first pass success of these LNA chip designs indicates the importance of a rigorous design/analysis methodology in millimeter-wave monolithic IC development     

110-120-GHz monolithic low-noise amplifiers

The authors discuss the development of 110-120-GHz monolithic low-noise amplifiers (LNAs) using 0.1-mm pseudomorphic AlGaAs/InGaAs/GaAs low-noise HEMT technology. Two 2-stage LNAs have been designed, fabricated, and tested. The first amplifier demonstrates a gain of 12 dB at 112 to 115 GHz with a noise figure of 6.3 dB when biased for high gain, and a noise figure of 5.5 dB is achieved with an associated gain of 10 dB at 113 GHz when biased for low-noise figure. The other amplifier has a measured small-signal gain of 19.6 dB at 110 GHz with a noise figure of 3.9 dB. A noise figure of 3.4 dB with 15.6-dB associated gain was obtained at 113 GHz. The authors state that the small-signal gain and noise figure performance for the second LNA are the best results ever achieved for a two-stage HEMT amplifier at this frequency band     

A Q-band monolithic balance resistive HEMT mixer usingCPW/slotline balun

A Q-band balanced, resistive high-electron-mobility-transistor (HEMT) mixer has been developed for integration in monolithic millimeter-wave receivers. The mixer consists of two AlGaAs/GaAs HEMTs, a coplanar-waveguide (CPW)-to-slotline local oscillator (LO) balun, and an active IF balun. CPWs are used to eliminate the backside or via-hole process step, which increases the circuit yield and shortens the processing time. The conversion loss of the mixer while downconverting a 42-46-GHz RF to a 2.3-3.2-GHz IF is between 4 and 8 dB using an LO drive of 14 dBm. A 17.5-dBm input two-tone third-order intermodulation intercept point is achieved with an LO drive of 10.5 dBm, while a 5.5-dBm input, 1-dB compression point can be achieved with an LO drive of 14 dBm. This is the first reported monolithic CPW resistive HEMT mixer operating at Q-band frequencies     

Ion-implanted n+ contacts for Ka band GaAs Gunn-effect diodes

Shallow (<1 ?m) n-type doping profiles with peak carrier concentrations of ? 8 × 1017 cm?3 have been formed by sulphur-ion implantation into vapour-phase GaAs epitaxial layers for improved Gunn-effect-diode contacts. Continuous wave output powers in excess of 250 mW were measured at 35 GHz, with the implanted n+ profile biased either as an electron cathode or anode contact.     

High efficiency pulsed GaAs Read impatt diodes

GaAs Read impatt diodes have been developed for pulsed operation in X and Ku bands. Conversion efficiencies of 32% and 29% have been measured for p+n+n?n+ (high-low) doping profiles grown by liquid phase and vapour phase epitaxy, respectively. Peak powers of 30 W in X band and 20 W in Ku band have been obtained with single mesas on gold plated heatsinks. Multiple mesas in parallel and diamond heatsinking were employed to improve thermal resistance. Microwave circuit and chip level power combining techniques were also investigated and greater than 90% combining efficiency was achieved on the chip level.