Phase matching technique for HTS filter-cryogenic LNA subsystem

A novel kind of phase matching technique for improving the reflection loss performance of HTS filter subsystems is proposed. The basic principle is that excellent performance is obtained by realizing the inverse phase relationship of the HTS filter's S/sub 22/ parameter and the cryogenic LNA's S/sub 11/ parameter at those frequencies where poor S/sub 11/-peaks of the HTS filter exist. We applied this technique to an HTS filter subsystem for 800 MHz wireless communication. Simulation and test results are presented, and it has been proved that this technique is not only effective but also easy to apply and low cost.