Novel miniature LTCC UWB bandpass filter

A novel compact design of UWB LTCC bandpass filter with semi-lumped circuit model was proposed and demonstrated successfully in LTCC process. The typical prototype of filter is very simple for synthesis and implemented in multilayer LTCC process as smaller chip components rather than traditional PCB microstrip planar circuit designs [1], [2] with large PCB space wasted. It behaves ultra-wide bandwidth of 3.1∼9.6GHz with insertion loss than 1.5dB cross whole passband and also 20dB minimum of spurious rejection outside band. The experiment shows its superiority and feasibility in miniature multilayer design and only little discrepancy between simulation and measurement on higher band edge and stop band. This is due to some parasitic contribution from via interconnection and non-closed microstrip line structures, and also the uncertainty of EM simulation on higher order mode excitation and measurement calibration in high frequency band.