Phase shifters based on surface mount phase leading bandpass unit cells using low temperature cofired ceramic(LTCC)

Surface mount unit cells for phase leading bandpass networks are developed for easy integration with microstrip lines on PCB for the phase shifter implementation. With the suitable design of layout and fabricated in low temperature cofired ceramic (LTCC), the bandpass network and its parasitic components are controlled to ensure the broadband operation. These unit cells of phase leading bandpass networks are mounted with phase lag microstrip lines on PCB for the design of broadband phase shifters. Unit cells can be cascaded in a single branch of power divider to create large phase shift or placed at different branch to give small phase shift while keeping sufficient return loss bandwidth. Four phase shfiters with phase shift of 22.5°, 45°, 90° and 135° are fabricated and measured using three different unit cells. Measured results of all four phase shifters show about 100% phase shift bandwidth, better than 10 dB return loss and less than 1.4 dB imbalance from 2.6 to 7.7 GHz.