Figure 2.

(A) A high resolution optical microscopic image of surface acoustic wave (SAW) resonator, adapted with permission from [102]. (B) The magnified image shows the geometrical details of IDTs i.e., the width of electrode is 1.69 µm and the distance between two consecutive fingers is 0.76 µm, adapted from [104]. (C) Images of different SAW resonators as going from 100 MHz to 1000 MHz, the size of devices changes from about 8 mm to 1 mm. This indicates that increase in fundamental resonance frequency of SAW demands more compact design.