Compact Terahertz On-Chip Filter With Broadband Rejection Based on Spoof Surface Plasmon Polaritons

In this letter, an on- chip integrated terahertz filter with broadband rejection based on spoof surface plasmon polaritions (SSPPs) is demonstrated. The grooves corrugated metallic SSPPs transmission line (TL) with etched complementary split ring resonators (CSRRs) has a pass-reject-pass characteristic in the frequency domain under the fundamental mode and high-order mode. In order to broaden the rejection band and isolation of the filter, SRRs with diverse resonance frequencies are loaded into the grooves of the SSPPs TL. The proposed die prototype is measured via an on- wafer GSG probing with the help of a vector network analyzer. Measured results demonstrate that, from the frequency range of 128 GHz to 158 GHz with a maximum relative bandwidth of up to 21%, the isolation of the filter is larger than 10 dB and the maximum isolation of up to 50 dB, which are in good agreement with the simulated ones. This proposed terahertz filter, with the advantages of compact structure and broad rejection band, has potential application in the terahertz integrated devices.