Low insertion loss and high isolation capacitive RF MEMS switch with low pull-in voltage

Micro electromechanical system (MEMS) shunt capacitive switches behave chiefly as a capacitor at both up and down states. Therefore, input-output matching for these switches is affected by varying the frequency. Although increasing the amount of capacitance at the up state reduces the actuation volt...

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Bibliographic Details
Published in:International journal of advanced manufacturing technology 2017-10, Vol.93 (1-4), p.661-670
Main Authors: Mafinejad, Yasser, Kouzani, Abbas, Mafinezhad, Khalil, Hosseinnezhad, Reza
Format: Article
Language:English
Subjects:
Actuation
C band
CAE) and Design
Capacitance
Circuits
Computer-Aided Engineering (CAD
Electric potential
Engineering
Frequencies
High impedance
Industrial and Production Engineering
Insertion loss
Mechanical Engineering
Mechanical properties
Media Management
Microelectromechanical systems
Network analysers
Original Article
Parameters
Switches
Transmission lines
Vibration meters
Voltage
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Description
Summary:Micro electromechanical system (MEMS) shunt capacitive switches behave chiefly as a capacitor at both up and down states. Therefore, input-output matching for these switches is affected by varying the frequency. Although increasing the amount of capacitance at the up state reduces the actuation voltage, it deteriorates the RF parameters. This paper proposes a remedy for this problem in the form of two short high-impedance transmission lines (SHITLs) which are included at both ends of the MEMS switch. The SHITLs are implemented through adoption of a discontinued CPW transmission line. With this implementation, the switch can be modelled as a T circuit, neutralizing a capacitance behavior of MEMS switch at the up state. The paper also proposes an optimised fabrication process to realize a flat and planar bridge for the suggested RF MEMS switch. The measurement recorded by SEM and AFM shows that the proposed method significantly improves the planarity of the membrane. The RF and mechanical parameters of the fabricated switch are evaluated by Vector Network Analyser and Laser Doppler Vibrometer. At the up state, the switch has a return loss less than −20 dB in the entire frequency band (C-K). The isolation at the down state is better than 10 dB for the lower frequencies and increases to values better than 18 dB for the higher frequencies. The measured pull-in voltage is almost 20 V and the mechanical resonance frequency is 164 kHz.
ISSN:0268-3768
1433-3015
DOI:10.1007/s00170-017-0558-9