M. Hikita et al., SAW FILTERS FOR HIGH-POWER USE IN CELLULAR RADIO PORTABLE PHONES, Electronics & communications in Japan. Part 2, Electronics, 77(4), 1994, pp. 38-50
Before a SAW filter is applied to the high-power section of a cellular
radio portable phone, it is necessary to develop a higher-performance
filter with a high-power capability and a small, nonlinear effect. In
this paper, as a new type of filter, a SAW resonator coupled filter o
f an extended type is proposed which uses two types of piezoelectric s
ubstrates. A design method considering the impedance matching between
the substrates is presented as well as the results of the experimental
duplexer satisfying the specifications of the cellular radio portable
phone for the United States. This filter has a third-order nonlineari
ty effect that results in the spurious response sensitivity much small
er than the conventional transversal type. These characteristics are a
lmost identical to those for the present dielectric resonator duplexer
for the forementioned use.