A 135GHz slotline bandpass filter using silicon/membrane technology

This paper presents the design and implementation of a second-order 135GHz bandpass filter (BPF) constructed on a thin suspended membrane structure. The BPF is built by cascading two U-shape slotline resonators formed on the ground plane. The input and output coupling are achieved by the microstrip line to slotline transition on the other side of the substrate. The unloaded quality (Q) factors of both I-shape and U-shape resonator due to the radiation, material and conductor loss are studied. The BPF is fabricated and measured, and it demonstrates a good agreement between the simulation and measurement results.