GaInP/GaAs HBTs: state of the art and future trends

This paper describes the design and performance of millimeter-wave balanced vector modulators employing the Marconi HBT MMIC technology. Two versions have been fabricated for operation at 38 GHz; the first employs normal Lange couplers whilst the second employs miniaturised microstrip couplem, which reduce the MMIC chip area by more than 40%. With a simple bias Calibration technique the circuits achieve near-perfect constellations w&h negligible amplitude and phase errors Over a wide bandwidth INTRODUCTIONIn recent years there has been a considerable interest in the use of direct carrier modulation in order to reduce the complexity and cost of microwave circuits [l-71. High performance direct vector modulators are required in modem microwave systems like phasedarrays, VSATs, LOS communications and radar applications, with the I-Q vector modulator being widely employed for quadrature modulation schemes [3-51. It consists of a phase splitting power divider that creates two orthogonal channels. Each channel consists of a bi-phase amplitude modulator, which is individually modulated and then combined at the output of the vector modulator. A common technique for realising the single stage bi-phase amplitude modulators in each channel is to a employ reflection topology using a Lange coupler with either coldFETs or cold-HBTs acting as switches on the direct and coupled ports [3-71. The cold-transistors can be controlled with an analogue bias signal to give a continuous range of resistance. Ideally, when the switches are ON the resistance would be zero (thus r=l), whilst when the switches are OFF the

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“…balanced HBT vector modulator fabricated using the MMT B20 HBT MMIC process [9]. The total area of the chip is 2.85mm2.…”

Section: Fig 2 Shows a Photograph Of The Monolithic 38 Ghzmentioning

confidence: 99%

Monolithic GaAs-InGaP HBT balanced vector modulators for millimeter-wave wireless systems

Ashtiani

Gokdemir²,

Vilches³

et al.

2000 IEEE Radio Frequency Integrated Circuits (RFIC) Symposium Digest of Papers (Cat. No.00CH37096)

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Thermal impedance variation of HBT's at high junction temperature operating conditions

Marsh

1999 Asia Pacific Microwave Conference. APMC'99. Microwaves Enter the 21st Century. Conference Proceedings (Cat. No.99TH8473)

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GaAs MMIC technology for IT and wireless communications

Marsh

Long²,

Edwards³

et al.

ICSE'98. 1998 IEEE International Conference on Semiconductor Electronics. Proceedings (Cat. No.98EX187)

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The market for Information technology and wireless communication systems is growing rapidly to meet the increasing demand for more capacity on existing networks and new systems with greater bandwidth. Access points to these networks are moving closer to individual desks and homes, driving up the volumes, and driving down the prices, of the required components. GaAs MMIC technology is ideally placed to meet these requirements, bringing with it small size and weight, low cost and inherent reproducibility. The MESFET. HEMT and HBT W I C processes at GMMT have produced .4SICs for commercial products in such systems, and are available as foundry services for external customers to design their own ASIC chips.

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GaInP/GaAs HBTs: state of the art and future trends

Cited by 3 publications

References 17 publications

Monolithic GaAs-InGaP HBT balanced vector modulators for millimeter-wave wireless systems

Monolithic GaAs-InGaP HBT balanced vector modulators for millimeter-wave wireless systems

Thermal impedance variation of HBT's at high junction temperature operating conditions

GaAs MMIC technology for IT and wireless communications

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