A GAAS HEMT MMIC CHIP SET FOR AUTOMOTIVE RADAR SYSTEMS FABRICATED BY OPTICAL STEPPER LITHOGRAPHY

A 77-GHz automotive radar system for collision avoidance and intellige nt cruise control has recently gained interest because of its huge mar ket potential, The questions of the optimum technological and system a pproaches leading to both low cost and high performance have not yet b een finally answered, The approach to this problem reported here diffe rs mainly in two aspects from the GaAs monolithic microwave integrated circuit (MMIC) solutions described earlier: 1) 0.12-mu m gate-length pseudomorphic high electron mobility transistors(PHEMT's) are fabricat ed by optical stepper lithography, 2) a coplanar design is used, A ful ly passivated PHEMT MMIC fabrication process is reported with current- gain and power-gain cutoff frequencies exceeding 115 and 220 GHz, resp ectively, 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 MMI C approach to meet all system requirements of an automotive radar sens or in a cost-effective and production-oriented way is shown, To our kn owledge, this is the first demonstration of W-band coplanar multifunct ional MMIC's fabricated by optical stepper lithography.