LTCC compatible ferroelectric phase shifters

Artikel i vetenskaplig tidskrift, 2005

Two phase shifters with novel topologies are presented. The phase shifters are based on LTCC compatible ferroelectric films with er=200, and tand=0.04 at 10 GHz. A Ku-band phase shifter is designed to provide DC bias independent matching in the wide frequency range. It has microstrip design where ferroelectric film is used as a substrate and requires relatively low DC bias voltages. The phase shifter showed -15dB matching in 50% bandwidth and 15deg/dB figure of merit. In X-band phase shifter the ferroelectric film is deposited on the low permittivity substrate. Using such two layered substrate a loaded line phase shifter based on coplanar-plate varactors is realized. The varactors are included in the circuit ground and are connected with the microstrip using vias. This designed allows reduction of overall loss due to more efficient use of ferroelectric. The figure of merit of this phase shifter is 20deg/dB at 10 GHz