Reconfigurable Comb-line Filters with 8-10.4 GHz Center Frequency by Using GaAs pHEMT Technology

A center frequency reconfigurable bandpass filter based on GaAs process is proposed by using a comb-line structure with variable capacitance loaded at the end. For the variable capacitance part, it is realized with an array based on varactors and switched capacitors. The final design of the reconfigurable filter has a size of $1.76\mathrm{~mm}1.66\mathrm{~mm}$, and the center frequency can be continuously tuned from 8 to 10.4GHz. Moreover, the filter can operate in the frequency range from 7.4 GHz to 11.6GHz with a $44.2\%$ tuning range. In addition to the good in-band performance, it also produces two transmission zeros at the upper and lower stopband, respectively, with high out-of-band rejection. Good agreement between simulation and measurement is obtained.