Design of CMOS MEMS Switches and Reconfiguable Filters

• Main Authors: Chien-Hsun Chen, 陳建勳
• Other Authors: Chia-Chan Chang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/16226322697069266568

碩士 === 國立中正大學 === 電機工程所 === 98 === In this thesis, CMOS MEMS switches and reconfigurable filters using the standard CMOS technology are analyzed, designed and fabricated. To fully integrate with the readily developed CMOS transceiver into a single chip, CMOS MEMS devices are more compatible than the traditional MEMS devices. For that reason, there is an urgent need to study and design the CMOS MEMS circuits, which motivates this work. The first circuit is a DC–40 GHz, sidewall-contact, triple-mode SPDT switch. It used two cantilevers bent to each other to make contact by electrostatic force. The contact can be ensured even though the residual stress wraps the cantilevers up. The second one is a DC–40 GHz quadro-mode SPDT switch. In this device, the circuit layout is carefully arranged so that the good isolation can be achieved between RF signal path and DC bias path. The third switch is designed for low pull-in voltage. This SPST switch consists of one main arm paralleled by numerous fingers to create a fishbone-like structure. The static electric force can be increased owing to those fingers so that the drive voltage can be dramatically reduced. The measured pull-in voltage is only 5 V. In addition, a band-reconfigurable bandstop filter is also proposed in this work. By varying the gap between the open-stubs and grounded-interdigital structures, the center frequency alters simultaneously. The simulation results show that the center frequency can be tuned from 60 GHz to 43.5 GHz and the isolation is about 32 dB. The last design is a bandpass filter-integrated SPST switch. Initially, this switch acts as a 60-GHz bandpass filter. When the interdigital structures are grounded, the transmission zeros are generated at 60 GHz, resulting in the OFF state of the switch.