A novel Ka-band MMIC coupled filter with harmonic suppression

Purpose A novel Ka-band compact parallel-coupled microstrip bandpass filter with harmonic suppression performance has been designed, implemented and tested on GaAs MMIC. Design/methodology/approach This proposed filter consists of modified coupled-line units with T-shaped open-stubs. Findings The proposed filter with T-shaped open-stubs is valuable in performance with low loss at fundamental frequency, suppression at harmonic frequencies and small size. The simulation is based on full-wave electromagnetic analysis and the measurement is based on chip test. It shows an insertion loss below 1.2 dB, return loss better than 20 dB in the pass band and high than 28 dB suppression at harmonic frequencies. Originality/value This Ka-band MMIC filter with harmonic suppression is attractive for the millimeter-wave system.