Phase-shifting coplanar stubline-filter on ferroelectric-thick film

The use of tunable coplanar stuhline-filters on a ferroelectric thick film has heen investigated For phase-shifter applications at rmm temperature. Circuits with one to three shorted, tunable low-impendance quarter-wavelength stubs have been designed and realized on Al₂O₃ substrate with a 3.2μm porous layer of screen-printed Ba_0.6Sro₄Tio₃ (EST). A phase shift of 31° (one element), 69° (two elemens) and 109° (three elements) could he achieved at 12.5GHz. Typical bandwidths (s₁₁ ~ <-10 dB)re between 7% and 11%. The Figure-of-Merit amounts to about 1O°dB.