高频声表面波滤波器用单指换能器

报道两种带宽极窄的采用单指换能器制作的声表面波滤波器。一种是利用单指换能器声同步频率与反射频率之间的相位叠加与相消来制作的体积极小（芯片面积只有采用双指换能器的三分之一不到）的高频极窄带声表面波滤波器，其３ｄＢ带宽的相位变化只１２０°；另一种是采用合理布局的单指无内反射换能器制作的高频极布带声表面波滤波器，其幅频特性同采用双指换能器制作的同类型的声表面波滤波器一样。最后给出了这两种声表面波滤波器的较详细的理论分析和实验结果。关键词

Single-electrode IDT for high Frequency SAW Filter

The paperreports two types of high frequency SAW filters with minimal narrowbandwidth using single-electrode IDT.One is made through the phase superposition and inter-cancel between the acoustic synchro frequency and the reflection frequency of the single-electrodeIDT.Its size is very small(the chip is less than one third of the chip with two-electrode),and thephase variation of 3 dB bandwidth is only 120 degrees;the other one is made with single-electrodeIDT without internal reflection,its magnitude-frequency characteristics are the same as that of thefilter with two-electrode IDT.The theoretic analysis in detail and the experimental results are given in the paper.