MMIC linear amplifiers - Design and fabrication techniques

The design and fabrication of monolithic microwave integrated circuit (MMIC) linear amplifiers based on high-performance GaAs FETs are discussed. The principles of MMIC design, which is mainly accomplished by computer-aided techniques based on active device and circuit-element models, are presented, together with the layout of a typical MMIC device, consisting of FET active layers, resistors, MIM capacitors, and high-impedance microstrip transmission lines. The horizontal Bridgmann and liquid encapsulated Czochralski techniques for the growth of the semi-insulating GaAs substrates for ion implanted FET fabrication are outlined, and circuit fabrication techniques, including ion implantation and photolithography, are illustrated for a planar GaAs MMIC chip incorporating an FET, Schottky barrier diode, bias resistor and MMIC capacitor. Design evaluation procedures are also considered. The potential for the high-volume, low-cost production of MMIC amplifier chips is pointed out, and the ultimate impact of MMIC amplifier technology as part of a multifunctional capability chip is indicated.