MONOLITHIC MICROWAVE INTEGRATED CIRCUIT

Low Q associated with passive components of monolithic integrated circuits (ICs) when operated at microwave frequencies can be avoided or mitigated using high resistivity (e.g., 100 Ohm-cm) semiconductor substrates (60) and lower resistance inductors (44′, 45′) for the IC (46). This eliminates significant in-substrate electromagnetic coupling losses from planar inductors (44, 45) and interconnections (50-1′, 52-1′, 94, 94′, 94″) overlying the substrate (60). The active transistor(s) (41′) are formed in the substrate (60) proximate the front face (63). Planar capacitors (42′, 43′) are also formed over the front face (63) of the substrate (60). Various terminals (42-1′, 42-2′, 43-1, 43-2′,50′, 51′, 52′, 42-1′, 42-2′, etc.) of the transistor(s) (41′), capacitor(s) (42′, 43′) and inductor(s) (44′, 45′) are coupled to a ground plane (69) on the rear face (62) of the substrate (60) using through-substrate-vias (98, 98′) to minimize parasitic resistance. Parasitic resistance associated with the planar inductors (44′, 45′) and heavy current carrying conductors (52-1′) is minimized by placing them on the outer surface of the IC where they can be made substantially thicker and of lower resistance. The result is a monolithic microwave IC (46, 58) previously unobtainable.