Design of a Ka-band bandpass filter with asymmetrical compact resonator

This paper presents the realization of millimeter-wave bandpass filter consisting of asymmetrical compact resonator structure (ACRS) by using 0.15-mum pHEMT process. The filter utilizes two series resonators, which are resonated at different frequencies and connected in parallel on GaAs substrate, to achieve the desired coupling impedance in passband for the wanted filter characteristics. The filter is not only very compact in size, but it also can demonstrate low insertion loss in passband and achieve two controllable transmission zeros at lower and upper stopbands, respectively. A prototype operated at 34 GHz was designed and fabricated. The measurements of the prototype agree very well with the EM simulations, which exhibits less than 3.2dB insertion loss in the passband and greater than 25 and 50 dB attenuations at the frequencies of the zeros, respectively.