A CRYOGENIC GAAS PHEMT FERROELECTRIC KU-BAND TUNABLE OSCILLATOR/

A Ku-band tunable oscillator operated at and below 77 K is described. The oscillator is based on two separate technologies: a 0.25 mu m GaAs pseudomorphic high electron mobility transistor (PHEMT) circuit optim ized for cryogenic operation, and a gold microstrip ring resonator pat terned on a thin ferroelectric (SrTiO3) film which was laser ablated o nto a LaAlO3 substrate. A tuning range of up to 3% of the center frequ ency was achieved by applying de bias between the ring resonator and g round plane. To the best of our knowledge, this is the first tunable o scillator based on a thin film ferroelectric structure demonstrated in the microwave frequency range. The design methodology of the oscillat or and the performance characteristics of the tunable resonator are de scribed.