42 GHz MMIC SPDT bandpass filter-integrated switch using HEMT loaded coupled lines

A 42 GHz MMIC single-pole-double-throw (SPDT) bandpass filter-integrated switch based on HEMT loaded coupled lines is proposed. The circuit integrates a microwave bandpass filter and an MMIC SPDT switch into a single circuit component and thus simplifies the T/R system designs. The proposed HEMT loaded coupled line is used to provide necessary coupling in the thru state and generate transmission zeros to improve isolation in the isolated state. In the thru state, a bandpass filter response at the centre frequency of 42 GHz with a 3 dB fractional bandwidth of 8% is measured. In the isolated state, an isolation of 29 dB is measured at the centre frequency.