Abstract
Because of there excellent features such as small-size, wide bandwidth, and low insertion loss, the ladder-type filters based on surface acoustic wave (SAW) technology have been widely used as radio-frequency (RF) filters in mobile communications. We can make wide bandwidth, and low insertion loss, the ladder-type SAW filters on a Cu-grating/15°LiNbO3 substrate structure. On the other hand, it is said that wide bandwidth filters is bad temperature characteristic. So this paper discusses dynamic temperature compensation of wideband ladder-type SAW filters. First, we investigate how wide tunability is achievable using variable capacitors parallel- and/or series-connectted to SAW resonators in the filter configuration. Second, we measured the temperature characteristic of resonator. Finally, we simulated temperature compensation of wideband ladder-type SAW filters. As a result, we were able to compensate the change of the characteristic with the ladder-type SAW filter connected variable capacitors.
