X-BAND AND KU-BAND AMPLIFIERS BASED ON SI SIGE HBTS AND MICROMACHINEDLUMPED COMPONENTS/

A double mesa-structure Si/SiGe heterojunction bipolar transistor (HBT ) and novel micromachined lumped passive components have been develope d and successfully applied to the fabrication of X- and Ku-band monoli thic amplifiers. The fabricated 5 x 5 mu m(2) emitter-size Si/SiGe HBT exhibited a de-current gain beta of 109, and f(T) and f(max) of 28 an d 52 GHz, respectively. Micromachined spiral inductors demonstrated re sonance frequency of 20 GHz up to 4 nH, which is higher than that of c onventional spiral inductors by a factor of two. Single-, dual-, and t hree-stage S-band amplifiers have been designed, based on the extracte d 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-sta ge 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 de signed and fabricated, showing a peak gain of 1.4 dB at 16.6 GHz, Matc hing circuits for all these amplifiers were implemented by lumped comp onents, leading to a much smaller chip size compared to those employin g distributed components as matching elements.