Planar Millimeter-Wave Circuits on Silicon Substrate

Highly insulating silicon with a resistivity higher than 2000 Ω·cm is very promising as the base material for monolithic integrated millimeter-wave circuits. In this case in the frequency range above 40 GHz the dominant loss mechanism of planar line structures is the skin effect in the conductors [1,2] and the conductivity of the silicon substrate does not degrade the circuit performance. We already have made theoretical and experimental investigations of microstrip lines on silicon substrates. Different microstrip resonators of linear and ring geometry were fabricated on 10000 Ω·cm silicon substrates. For microstrip lines with a w/h ratio of 1. where w is the conductor width and h is the substrate height, the attenuation was found to be 0.6 dB/cm at 90 GHz. A 95 GHz microstrip oscillator with a discrete single drift region silicon impatt diode and a planar array antenna with 96 elements on an area of 8 mm × 12 mm have been fabricated on highly insulating silicon substrates [2]. In this paper we present new results on a continuously operating oscillator circuit and theoretical investigations of the disk resonator structure. In this oscillator a double drift region silicon impatt diode is used.