Packaged Tunable Notch Filters

One of the student design competitions on packaged tunable notch filter design was held during the 2013 IEEE Microwave Theory and Technique Society (MTT-S) International Microwave Symposium (IMS2013) in Seattle. This article describes the winning work at the student competition. According to the competition design rules, the tunable notch filter structure must be planar. The lumped surface-mounted components, including resistors, capacitors, and varactors, are allowed and must be tightly mounted on the printed circuit board. The printed circuit board will be mounted in a metal package, and it must be securely sealed with a copper tape lid. The metal package was placed on another unenclosed printed circuit board with the 50-X traces, connecting the radio-frequency (RF) port of the package to the standard 50-X female subminiature version A (SMA) connector. The varactor diode and the metal package are provided by the competition committee. The filter performance was evaluated based on the measurement performance between the SMA connectors. In this competition, it provided the S-parameter measurement with a voltage range between 0 and 20 V to realize two bands of the tunable notch filter. The first band specifications are (1) the notch band frequency: 685-730 MHz (2) in-band insertion loss: > 20 dB (3) out-of- band (f<; f1 and f> f2 ) insertion loss: <; 4 dB.