A novel integrable surface acoustic wave notch filter

Although surface acoustic wave (SAW) notch filter was investigated in the past, the structures of these devices often needed the extra lumped-element such as resistance R, capacitance C, and inductance L so that the devices are complex and integrated hardly. From this, we offer a simple kind of the planar structure to the novel SAW notch filters that have smaller size and can be fabricated easily. We adopt the SAW and the interdigital transducer's (IDT's) theory to fabricate the SAW notch filter. In this paper, we use an IDT finger width 8 μm with conventional photolithography process, lift-off technique, and IDT electrode to fabricate on 128° rotated YX-cut lithium niobate (LiNbO₃). Finally, we get the frequency responses of the novel SAW notch filter with the center frequency 113.4 MHz, the 3 dB bandwidth 0.36%, and the insertion loss S₂₁ = -10.583 dB.