Wideband three-transducer SAW filters using unidirectional IDTs on U-shaped MSCs with insertion loss of 1 dB

This paper presents wideband three-transducer SAW filters using unidirectional IDTs on U-shaped MSCs. In the filters a self-matching effect is used when a static capacitance of an IDT is compensated by an acoustic radiation susceptance. 30-70 MHz filters on 128° YX, 64° YX, 41° YX LiNbO3 have shown an insertion loss of 1 dB, 3-dB fractional bandwidth of 3.5-10% with low ripple of 0.1 dB, stopband attenuation of 10-15 dB. 165, 169 MHz SAW filters for the front-end stages of mobile transceivers have shown an insertion loss of 1-1.8 dB, 3-dB bandwidth of 5.7-11 MHz with a ripple of 0.2 dB, stopband attenuation of 12-40 dB. The filters did not require matching networks, were mounted in the SMD packages (5×5×1.8 mm).