Saw Applications
Token Electronics Industry Co., Ltd.
Taiwan: No.137, Sec. 1, Zhongxing Rd., Wugu District,
New Taipei City, Taiwan, R.O.C. 24872
Tel: +886 2981 0109 Fax: +886 2988 7487
China: 12F, Zhong Xing Industry Bld., Chuang Ye Road,
Nan Shan District, Shen Zhen City,
Guang Dong, China 518054
Tel: +86 755 26055363; Fax: +86 755 26055365
Web: www.token.com.tw
Email: rfq@token.com.tw
Version:
January 13, 2017
Taiwan Factory: +886 2 29810109
http://www.token.com.tw
rfq@token.com.tw
China Factory: +86 755 26055363
Page: 1/2
Saw Applications
Saw Applications for Telecommunications
Definition of Saw
Surface Acoustic Wave (SAW) is a wave propagating along the surface of an elastic substrate.
Frequency of Saw is:
F = V / λ
Where V is the velocity of SAW (~3,100m/s), λ is the IDT period.
Types of Saw Devices
Figure-1 - Basic Saw Device
The device in (Figure-1) is a basic delay line, because the wave takes some time to travel between the
transducers - typically 1 μs for 3 mm of path length. This is very compact compared with EM waves
which, in free space, need 300 m of path for 1 μs delay. The device can also be used as a band pass
filter, because the transducers operate most effectively when the saw wavelength equals the transducer
pitch - at other frequencies the waves generated by individual gaps are not in phase, so the wave
amplitude falls off as the frequency is changed.
Another basic device is the resonator. This uses arrays of metal strips, with pitch λ/2, as reflectors of
the waves. These arrays can give strong Saw reflections, and two arrays can be used to form a saw
cavity with high Q, up to 105. Such resonators are often used for high-stability oscillators.
The above devices are just some basic types. Many unique variations are possible for saw devices, and
their applications range from piezoelectric strain gauges to pulse compression radar, to cellular
handsets.