Ferroelectrics, which exhibit electric field dependent dielectric constant, have been of interest for possible applications on electrically controllable devices. Especially, dielectric constant of ferroelectrics could be adjusted in few microseconds to response on externally applied electric field, which made it possible ferroelectrics being used in microwave tunable devices.
In this paper, Effect of BaSrTiO<sub>2</sub>/Li<sub>2</sub>CO<sub>3</sub> on low temperature sintering and BaSrTiO<sub>2</sub>/MgO on dielectric property of thick films has been investigated for variable capacitor on RF frequency band. The thick films were fabricated by the tape casting and then the structural and dielectric properties as a function of an addition composition of plastic-sizer ratio and sintering temperature were studied. For the thick film sintered at 1100°C, it was densified to 96 % of BaSrTiO<sub>2</sub> theoretical density by the addition of 3 and 10 w% BaSrTiO<sub>2</sub>/Li<sub>2</sub>CO<sub>3</sub>. Dielectric constant increased and tuning range increased with the increased of BaSrTiO<sub>2</sub>/Li<sub>2</sub>CO<sub>3</sub> content, which probably can be explained by the substitution of Ba<sup>3+</sup>, Li<sup>1+</sup> on BaTiO<sub>3</sub> lattice. The tunability and dielectric loss of the BaSrTiO<sub>2</sub>/Li<sub>2</sub>CO<sub>3</sub> thick film, sintered at 1150°C, were about 43 % and 0.234 at 10~15 MHz respectively. In case of BaSrTiO<sub>2</sub>/MgO, Dielectric constant decreased and tunability increased with the added of BaSrTiO<sub>2</sub>/MgO.
Multifunction corresponding to multimedia age has furthermore required high integration to the devices at microwave band, so more evolution for multi-layer integration like system on chip(SoC) becomes to be necessary. In wireless mobile communication, portable mobile phones grew up to a huge market. Microwave devices have played an important role in the wireless communication systems. One challenge in the implementation of circuit integration is in the design of micro wave band pass filter with thin film MOM capacitor and spiral inductor. In this paper, Cu and TaO thin film with RF sputtering was deposited for inductor and capacitor on the SiO<sub>2</sub>/Si(100) substrate. MIM capacitor and spiral inductor was fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, an important devices for mobile communication. Based on the high-Q values of passive components, MIM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and was 5 dB for a 900 MHz filter. This paper also discusses a theoretical analysis and practical design to L-C band pass filter.
Soft magnetic composite materials find increasing use in electrical motors, replacing existing laminate materials. In this study, the composites have been fabricated with micro- and nano-sized highly pure iron powders coated by polyester and phenolic resins. Soft magnetic composite materials have been pressed into ring type for magnetic properties measurement, and bar type for mechanical properties measurement over the pressure range up to 870 MPa. Some
samples have subsequently been heat treated to 300°C. The effect of the amount of organic materials on the magnetic properties like as permeability, magnetic flux density, core loss and green density were investigated. And electrical resistivities were also examined. On the addition of the organic coating materials of 5 wt%, green density of the compacted composites is most high of 6.9 g/cm<sup>3</sup>, and magnetic properties are also better. For the case of 5 wt% polyester resin, the effect of powder size with 100 nm, 3 μm, 10 μm and 53 μm were examined. Both the green density and the magnetic properties are best for the particle size of 10 μm. Fine particles below 3 μm easily agglomerate each other, and
homogeneous coating of each particle surface is difficult.
In this study, spiral inductors on the SiO<sub>2</sub>/Si(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of 0.7~2.0 μm was deposited on the substrate. Square inductors were fabricated through the wet chemical etching technique. The inductors are completely specified by the number of turns, coil width and the coil spacing. Both the width and spacing were varied from 10 to 50 μm and from 20 to 70 μm, respectively. The Frequency dependency of inductance and Q factor were investigated to analyze the performance of spiral inductors.
The design, simulation, modeling and characterization of low-temperature co-fired ceramics (LTCC) RF switch module for GSM band applications were investigated. RF switch circuits were simulated by ADS tool, manufactured using a LTCC multi-layer in the GSM band. It was integrated with low pass filter on switch module. Insertion and return losses at 900 MHz of the low pass filters were designed to lower than 0.3 db and higher than 12.7 db respectively. The RF switch module was constructed, containing 10 embedded passives and 3 surface mounted components integrated on 4.6×4.8×1.2 mm<sup>3</sup> volume, 6-layer integrated circuit. The insertion loss of switch module at 900 MHz was about 11~19 db.