Low Actuation Voltage Capacitive Shunt RF-MEMS Switch Having a Corrugated Bridge

Yo-Tak SONG  Hai-Young LEE  Masayoshi ESASHI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.12   pp.1880-1887
Publication Date: 2006/12/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.12.1880
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Emerging Microwave Techniques)
Category: Passive Circuits/Components
Keyword: 
low-actuation voltage,  RF-MEMS,  capacitive shunt switch,  microwave and millimeter-wave,  corrugated bridge,  residual stress,  

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Summary: 
This paper presents the design, fabrication and characterization of a low actuation voltage capacitive shunt RF-MEMS switch for microwave and millimeter-wave applications based on a corrugated electrostatic actuated bridge suspended over a concave structure of coplanar waveguide (CPW), with sputtered nickel as the structural material for the bridge and gold for CPW line, fabricated on high-resistivity silicon (HRS) substrate using IC compatible processes for modular integration in a communication devices. The residual stress is very low because having both ends corrugated structure of the bridge in concave structure. The residual stress is calculated about 3-15 MPa in corrugated bridge and 30 MPa in flat bridge. The corrugated bridge of the concave structure requires lower actuation voltages 20-80 V than 50-100 V of the flat bridge of the planar structure in 0.3 to 1.0 µm thick Ni capacitive shunt RF-MEMS switch, in insertion loss 1.0 dB, return loss 12 dB, power loss 10 dB and isolation 28 dB from 0.5 up to 40 GHz. The residual stress of the bridge material and structure is critical to lower the actuation voltage.