3-D Compact Metamaterial Bandstop Filter With TSV-Based Split Ring Resonators

Miniaturizing on-chip band stop filters (BSFs) is a key challenge for improving the integration of monolithic microwave integrated circuits (MMICs). In this letter, we present a high-performance, low-profile BSF based on split ring resonators (SRRs), designed using advanced three-dimensional (3- D) packaging process that includes through silicon via (TSV) and redistribution layer (RDL) technologies. The metamaterial SRR units are formed by TSV arrays embedded in the substrate, effectively reducing the occupied area while maintaining band-rejection characteristics. To meet the special shielding requirements of the TSV-based SRRs, a stepped 3-D patterned ground shield (PGS) is proposed to enhance the quality factor. The results show that the proposed 3-D SRR-based BSF achieves over 20 dB of bandstop attenuation in the 3.5-4 GHz frequency band, with an insertion loss of 0.24 dB. It occupies a chip area of 19.4 mm², with an electrical size of only 0.0029 λ<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</i>².