Characteristics of tapped microstrip bandpass filter in BiNbO4 ceramics

Abstract

The dielectric properties of BiNbO4 (BN ceramics) sintered at low temperature with CuO and V2O5 additives were determined. BN ceramics containing 0.07 wt % V2O5 and 0.03-0.05 wt % CuO sintered at 900 degrees C had a dielectric constant of 44.3, temperature coefficient of resonance frequency tau(f) of 2 p.p.m. degrees C-1 and Qxfo value of 22 000. A multilayer type band pass filter using tapped resonators and conventional resonators was designed at 1.855 GHz and PCS (personal communication system) applications. By adopting an input/output-tapping scheme the chip filter structure becomes simpler and needs fewer layers than using the conventional input/output-coupling scheme. The green ceramic sheet the for band pass fi Iter was manufactured by a tape casting process and a multilayer type band pass filter was fabricated with a silver electrode. The simulated characteristics, including spurious resonance of the designed filters, are compared with the measured ones. The measured frequency of both exhibited similar tendencies. Even though the centered frequency was measured to shift about 90 MHz downward, the characteristics at pass band and spurious resonance characteristics were similar to that of a simulation. (C) 1998 Kluwer Academic Publishers.