通过理论仿真, 该文研制了一种改进型的3IDT-LCR结构, 并基于该结构在42°Y-X LiTaO3压电基片上研制出一种低损耗、小矩形系数的SAW滤波器。滤波器标称频率为253.75 MHz, 实测插入损耗1.05 dB, 低端带外抑制接近80 dB, 高端带外抑制接近65 dB, -1 dB带宽10.52 MHz, -3 dB带宽12.54 MHz, -40 dB带宽16.68 MHz, 矩形系数1.33。实测结果表明, 该改进型3IDT-LCR结构的SAW滤波器具备低插入损耗、小矩形系数和高带外抑制的特点。

In this paper an improved 3IDT-LCR structure was developed by theoretical simulation, and a low-loss SAW filter with small rectangular coefficients was successfully developed based on this structure. The device adopts 42°Y-X LiTaO3 piezoelectric substrate with nominal frequency 253.75 MHz, measured insertion loss 1.05 dB, lower-side stopband rejection nearly 80 dB, higher-side stopband rejection nearly 65 dB, -1 dB bandwidth 10.52 MHz, -3 dB bandwidth 12.54 MHz, -40 dB bandwidth 16.68 MHz, and rectangular coefficient 1.33. The measured results show that the SAW filter with improved 3IDT-LCR structure can achieve the performance characteristics of low insertion loss, small rectangular coefficient, and high stopband rejection at the same time.