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A GaAs HEMT MMIC chip set for automotive radar systems fabricated by optical stepper lithography

Ein GaAs HEMT-Chipsatz für KFZ-Abstandswarnradarsensoren unter Verwendung optischer Stepperlithographie


IEEE journal of solid-state circuits 32 (1997), Nr.9, S.1342-1349
ISSN: 0018-9200
Fraunhofer IAF ()
automotive applications; coplanar receiver MMIC; coplanar transmitter MMIC; Kfz-Abstandswarnradar; koplanarer Empfangschip; koplanarer Sendechip

A 77-GHz automotive radar system for collision avoidance and intelligent cruise control has recently gained interest because of its huge market potential. The questions of the optimum technological and system approaches leading to both low cost and high performance have not yet been finally answered. The approach to this problem reported here differs mainly in two aspects from the GaAs monolithic microwave integrated circuit (MMIC) solutions described earlier: 1) 0.12-mu m gatelength pseudormorphic high electron mobility transistors (PHEMT's) are fabricated by optical stepper lithography, 2) a coplanar design is used. A fully passivated PHEMT MMIC fabrication process is reported with current-gain and power-gain cutoff frequencies exceeding 115 and 220 GHz, respectively. The design and performance of a chip set consisting of four different MMIC's [voltage controlled oscillator (VCO), harmonic mixer, transmitter, receiver] are described. The great potential of this MMIC approach to meet all system requirements of an automotive radar sensor in a cost-effective and production-oriented way is shown. To our knowledge, this is the first demonstration of W-band coplanar multifunctional MMIC's fabricated by optical stepper lithography.