Abstract

The design and performance of two tuneable GaAs MMIC band stop filters is presented. The first filter was designed to demonstrate the excellent properties of the resonating tank consisting of a varactor diode and a novel active inductor. On the basis of the first filter, a second filter is designed with improved performance, with respect to gain, noise figure and bandwidth. This filter is tuneable from 9 to 11 GHz, with a notch depth of more than 25 dB. The filter exhibits a gain of 4 dB which is flat within 0.5 dB from 6 to 18 GHz. The -10dB notch bandwidth amounts to 60 MHz for a 10 GHz centre frequency. Large-signal behaviour was investigated and hence we believe to report the first fully characterised MMIC tuneable narrow band stop filter at X-band.