| 摘要 |
<p>An active filter includes a resonator surface acoustic wave (SAW) filter with at least two ports, an amplifier, and a phase shifter. The SAW filter has either one resonant mode or two or more resonant modes which couple mutually to show characteristics of a multi-stage filter. The amplifier and the phase shifter are connected so as to compensate loss caused by the SAW filter.</p> |
