P2H-1 High Frequency and High Selectivity Balanced Front-End SAW Modules for Handheld Transceivers

This paper presents new high frequency balanced front-end SAW modules with a wide fractional bandwidth of 1.5-5% for the 240-400 MHz handheld transceivers. The modules contain 2 SAW filters connected across a low-noise amplifier. The 4-pole balanced longitudinally-coupled resonator SAW filters on 42deg YX LiTaO₃, 64deg YX and 41deg YX LiNbO₃ are used in these modules. The first filter is realized in a three-transducer scheme. The second filter is built in a two-transducer scheme. A combination of these two filters provides very high selectivity of the module without using the weighted transducers in the filters. The optimization of a SAW filter-amplifier-SAW filter system is provided with a computer simulation using an equivalent circuit model. The 246-400 MHz samples of the balanced front-end modules have shown an amplitude ripple of 1 dB, 10-12 dB gain, high suppression of 90 dB. A noise figure of 2 dB was provided with a current consumption of 5-7 mA and supply voltage of 3 V. The modules were housed in the 13.3times6.5times1.8 mm SMD packages.