2-IDT double-mode SAW filters with decreased insertion loss and advanced functionalities
This paper presents new 2-IDT double-mode SAW (DMS) filters with the decreased insertion loss and advanced functionalities: low input and output impedances, balanced operation and impedance conversion on 42º YX LiTaO3, 64º YX and 41º YX LiNbO3. To decrease the input and output impedances and resistive losses of the IDT electrodes the parallel connection of the 2-IDT DMS filters in the different acoustic tracks is used simultaneously reducing the aperture of each track. For an impedance conversion a series connection of the output IDTs in the 2 parallel acoustic tracks of the filters is used. To increase the selectivity of the filters the cascaded connection and phase weighting are employed. The constructional and topological optimization of the SAW filters is provided with a computer simulation using an equivalent circuit model. The 240–367 MHz samples of the balanced SAW filters have shown an insertion loss of about 1 dB, stopband attenuation of about 20 dB, impedance conversion from 50–75 Ω at the input to 200–300 Ω at the output in a wide fractional bandwidth of 2–6%. Two cascaded filter has provided an insertion loss of less than 2 dB and stopband attenuation of about 50 dB. The filters are housed in the 5×5×1.35 mm SMD packages.
Balanced low-loss longitudinally-coupled double-mode resonator saw filters with impedance conversion
This paper presents the new wideband balanced low-loss SAW filter with impedance conversion from 50-100 Omega to 200-300 Omega in a wide fractional bandwidth of 2-6%. The two types of the longitudinally-coupled double-mode resonator filters on 42deg YX LiTaO3, 64deg YX and 41deg YX LiNbO3 are used for this purpose. The first type of the filters is realized as a two-transducer scheme. The second type of the filters is built as the three-transducer scheme. The impedance conversion in the two-transducer filters is provided by a sectional output transducer. The impedance conversion in the three-transducer filters is attained by a series connection of the side transducers. The optimization of a SAW filter is provided with a computer simulation using an equivalent circuit model. The 240-361 MHz samples of the balanced SAW filters have shown an insertion loss of 2-3 dB, stopband attenuation of 20-50 dB. The filters were housed in the 5x5x1.35 mm SMD packages.
The Determination of Physicochemical Characteristics of Biodiesel and Its Blending Oils
The viscosity,combustion heat,sulfur content,carbon residue,ash,flash point,moisture and cetane value of biodiesel and its blending oils with diesel were determined.The influence of temperature on the viscosity was studied,and the physicochemical characteristics of biodiesel and its blending oils were compared with diesel.The results indicated that biodiesel and its blending oils had some superior performances and good application prospect.