X- and ku-band amplifiers based on si/sige hbt's and micromachined lumped components

A double mesa-structure Si/SiGe heterqjunction bipolar transistor (HBT) and novel niicrornachined lumped passive components have been developed and successfully applied to the fabrication of X- and Ku-band monolithic amplifiers. The fabricated 5 × 5 μm² emitter-size Si/SiGe HBT exhibited a de-current gain β of 10⁹, and f_T and f_max of 28 and 52 GHz, respectively. Micromachined spiral inductors demonstrated resonance frequency of 20 GHz up to 4 nH, which is higher than that of conventional spiral inductors by a factor of two. Single-, dual-, and three-stage X-band amplifiers have been designed, based on the extracted active- and passive-device model parameters. A single-stage amplifier exhibited a peak gain of 4.0 dB at 10.0 GHz, while dual- and three-stage versions showed peak gains of 5.7 dB at 10.0 GHz and 12.6 dB at 11.1 GHz, respectively. A Ku-band single-stage amplifier has also been designed and fabricated, showing a peak gain of 1.4 dB at 16.6 GHz. Matching circuits for all these amplifiers were implemented by lumped components, leading to a much smaller chip size compared to those employing distributed components as matching elements.