Development of IMD3 Measurement System Around 5 GHz Using HTS Notch Filters

We developed a third intermodulation distortion (IMD3) measurement system around 5 GHz in order to realize superconducting transmit filters in a mobile communication system. We added a high temperature superconducting (HTS) notch filter to the simple IMD measurement system and then focused on reducing the system noise levels. We designed and fabricated the HTS notch filter composed of three-pole hair-pin resonators with high attenuation and sharp skirt characteristics. The IMD characteristics measured using the system were reduced by 49.7 dBm by using the HTS notch filter.