A 55 GHz Bandpass Filter Realized With Integrated TEM Transmission Lines

A compact 4-pole bandpass filter centered at 55 GHz with a 13.6% bandwidth is realized using an integrated three dimensional microfabrication process. The filter has an almost exact match to the design simulations except for a shift in the center frequency that is less than 1.3%. Measured insertion loss is 2.4-3.5 dB. The filter is very compact, measuring less than 0.86 mm (ap lambda/6) by 1.9 mm (ap lambda/3) by 0.3 mm (ap lambda/15). This filter clearly demonstrates the potential of three dimensional microfabrication processes for the realization of millimeter wave filters