A Compact LC Bandpass-Filter with Controllable Transmission Zeros Using IPD Technology

in this paper, a compact LC bandpass filter using GaAs-based IPD technology is proposed. The size of the filter is 1.36×0.6 mm
²
. The center frequency of the filter is 2.40 GHz, the return loss is more than 17 dB between 2.17 GHz and 2.64 GHz, and the insertion loss is less than 3.3 dB in the passband. To improve frequency selectivity, one transmission zero is obtained near the upper side of the passband by introducing cross-coupling between the first and third resonators. The out-of-band rejection is more than 30 dB from 3.86 GHz to 15.60 GHz.