Micropackaged Compact Switchable Filters With High Isolation in 3-D TSV-MEMS Process

Abstract

Commercial switchable filter banks are usually with bulky size; nowadays, they are highly preferred to feature compact size, self-packaging, and high integration. To meet these challenging requirements, this article proposes a micropackaged switchable filter bank for 3-D heterogeneous integration. The filters are stacked and integrated with switches using an in-house developed 3-D silicon process. These advanced silicon process steps mainly include through-silicon via (TSV), microelectromechanical systems (MEMS), and wafer-to-wafer bonding. To demonstrate this configuration and also meet industrial requirements, a four-channel switchable filter bank is designed, fabricated, and measured. Measurement results show that the chip module achieves a minimum insertion loss of 4.2 dB, including switch loss in the passbands, and a high isolation than 40 dB. To the best of the authors’ knowledge, this is the first demonstration of a fully integrated and micropackaged switchable filter chip in a 3-D TSV-MEMS process. Moreover, the size of the switchable filter bank is significantly reduced by 98.4%, i.e., it is reduced from $32\times 29.5\times7.5$ mm3 of a typical industrial counterpart to $15\times 7.5\times1$ mm3 of the proposed chip module.