Duncan M. Smith

25-42 GHz GaAs heterojunction bipolar transistor low phase noise push-push VCOs

Two push-push thin-film VCOs (voltage-controlled oscillators) utilizing GaAs-AlGaAs heterojunction bipolar transistors that cover the 25-42 GHz frequency range are presented. Key features of the designs are: greater than 33% continuous tuning bandwidth, SSB phase noise less than -70 dBc/Hz at 100 kHz offset, and better than -90-dBc fundamental spur suppression. Over 10 GHz of tunability has been achieved using this design. It is suggested that this wide tuning range in a single oscillator allows significant size, weight, and power improvements in wideband communication systems.<<ETX>>

A family of low cost high performance HEMT MMICs for commercial DBS applications

A family of GaAs HEMT MMICs have been developed for use in Direct Broadcast Satellite TV (DBS) US, Japanese, and European markets. These designs are very compact, high performance, and self-biased. They are meant as building blocks for low noise block (LNB) downconverters. Described in this paper are the receiver chip, low noise amplifier, and self-biased single HEMT device (should a MIC LNA be preferred). The key design is the receiver chip with a nominal gain of 38 dB and NF of less than 3 dB for the US band. This paper presents a description of each design, a performance summary, as well as information describing their actual use in an LNB design.<<ETX>>A family of GaAs HEMT MMICs have been developed for use in Direct Broadcast Satellite TV (DBS) US, Japanese, and European markets. These designs are very compact, high performance, and self-biased. They are meant as building blocks for low noise block (LNB) downconverters. Described in this paper are the receiver chip, low noise amplifier, and self-biased single HEMT device (should a MIC LNA be preferred). The key design is the receiver chip with a nominal gain of 38 dB and NF of less than 3 dB for the US band. This paper presents a description of each design, a performance summary, as well as information describing their actual use in an LNB design.<<ETX>>

A novel monolithic HEMT harmonic mixer at Q-band

A novel Q-band monolithic harmonic mixer has been designed and fabricated using the 0.15 /spl mu/m pseudomorphic InGaAs-GaAs HEMT process for the first time. This high performance mixer is capable of downconverting a Q-band RF signal with the 12th, 14th or 16th harmonic of a S-band LO signal to produce a signal suitable for a phase locked loop. This compact mixer consists of antiparallel HEMT Schottky diodes with a lumped element IF and LO diplexer and a RF band-pass filter. Measured data shows agreement between simulations and measurements. Total chip size is 1.0 mm/spl times/2.5 mm.<<ETX>>

A quenchable GaAs HBT X-band VCO for switched band synthesizer architectures

The authors have achieved the lowest phase noise reported for an HBT VCO at X-band. The VCO employs an off-chip quarter-wave open stub microstrip resonator fabricated on a 50 mil quartz substrate and a shunt-varactor diode for frequency tuning. At a center frequency of 8.9 GHz, the VCO achieves -103 to -105 dBc/Hz at 100 kHz over a tuning bandwidth of 140 MHz (1.6%). By reducing the unloaded Q of the microstrip resonator, a 770 MHz tuning bandwidth (8.6%) can be achieve with a phase noise ranging from -98.5 to 100.5 dBc/Hz. Without a tuning varactor, a record minimum phase noise of -112 dBc/Hz was achieved at a center frequency of 8.3 GHz which benchmarks the lowest reported phase noise achieved for an HBT oscillator at X-band. The HBT VCO MMIC features a monolithically integrated PIN diode quench circuit which enables the VCO to be used in switchband synthesizer applications.

A high performance transceiver chipset for millimeter-wave commercial digital communication systems

A high performance Q-band monolithic HEMT transceiver chipset has been developed for millimeter-wave commercial digital radio systems. This highly compact transceiver chipset consists of low noise amplifier, power amplifier with detector, voltage controlled oscillator with buffer amplifier, mixer and harmonic mixer. The chipset has demonstrated high yield making it suitable for high volume commercial applications.<<ETX>>

A MMIC chip set for V-band crosslink communication systems

V-band communication crosslink systems are being developed to take advantage of high atmospheric-attenuation characteristics. Because of strict weight, volume, and cost constraints of modern satellites, MMIC technology was chosen over conventional MIC approaches to deliver lighter, smaller, and higher performance communication systems. Through the MIMIC Phase 2 program, sponsored by ARPA and the Army Research Laboratory, TRW has developed a chip set for such a crosslink. Requirements from several insertion programs have been integrated to design an architecture that is generic, but flexible enough for expansion or reconfiguration to support these programs. The chip set includes nine highly integrated, multi-function MMICs configured to provide a complete V-band transceiver system.<<ETX>>

Competitive dual use MMIC technologies and products

Competitive dual use GaAs MMIC technologies have begun to appear in the market, successfully countering discretes and silicon ICs. The three choices of MESFET, HEMT and HBT requires an optimum selection design task, based on cost. Due to the variety of MMIC functions required and frequency ranges needed, the selection task is complex and results in different application niches for each technology. In the last 10 years and even longer, the successful development of MMIC technology was propelled primarily by the needs of defense and space systems, to achieve considerably smaller size and lower cost of microwave hardware. Therefore, government funding sources were primarily depended upon programs such as the DoD MIMIC Program. It was always anticipated that commercial spin-offs of some significance would occur to create an important international industrial base in telecommunications and other areas. In the last two years, these spin-offs have become more visible. Which MMIC technologies will have dual use for both military and commercial? The answer is complex because various MMIC technologies (silicon, GaAs MESFET/HEMT/HBT) have various cost and performance tradeoffs. One must perform an optimum technology selection in many applications. Yet certain niches are becoming apparent based on frequency, power level and function, as well as volume.<<ETX>>