Microstrip and coplanar SiGe-MMIC oscillators

We report on design, technology, and experimental results of microstrip and coplanar Si-SiGe HBT Ks-band oscillators integrated monolithically on high resistivity silicon. The tuning range of the microstrip VCO was 100 MHz around 22.8 GHz and the output power reached-7 dBm with a conversion efficiency of 1%. The coplanar LC oscillators reached output powers of up to 1 dBm with a conversion efficiency of 358 at 28.1 GHz and 37.8 GHz. This exceeds the requirements for subharmonic injection locking of transit-time diodes like IMPATT oscillators. With the availability of such HBT oscillators extremely compact and low-cost FMCW radar circuits for use in industrial and traffic sensor systems will become possible in the ISM-bands 24 GHz (direct operation) and 76.5 GHz (by subharmonic injection locking).