Two K-band active band-pass filters using 0.15-μm GaAs pHEMT technology, with one fixed-frequency and the other tunable, are designed, fabricated, and tested. The fixed-frequency filter has its central frequency at 22.6 GHz, with 900-MHz band-width (4%). The tunable filter can be tuned from 19.5 to 21.5 GHz with the same bandwidth. Both circuits have a common size of 1 mm × 1 mm. To our knowledge, the tunable filter is the highest frequency tunable active filter ever reported.
- Active band-pass filter