On-Chip CPW Low-Pass Filter with 50–110 GHz Bandstop in 400 nm Metal Thickness Technology Towards Lab-Level Ka-Band MMICs

This paper presents a millimeter-wave low-pass filter to investigate the RF performance of passive structures in a lab-level thin metal micro-nano processing technology. It consists of 3-stage periodic stepped-impedance cell to have a slow-wave structure to offer a high attenuation of stop band with a compact size. The total size of the chip is less than 1.1 mm². It achieves an insertion loss of less than 2 dB at a frequency range from 0 to 110 GHz with a measured cut-off frequency around 40 GHz. A rejection of higher than 20 dB is measured in a stopband from 52 to 110 GHz, which is larger than 2 times of fundamental frequency. The measurement agrees well with the simulation results. It shows the potential of RF passives in a lab-level thinner metal thickness technology towards monolithic microwave integrated circuits.