A low-loss MEMS tunable capacitor with movable dielectric

This paper reports a MEMS tunable capacitor with a new actuation principle. The new design adopts electrostatic actuation of an electrically floating movable dielectric. This enables us to achieve a high Q factor by eliminating the loss associated with springs in the RF signal path. Also, the design...

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Bibliographic Details
Main Authors: Zhu, Y., Yuce, M.R., Moheimani, S.
Format: Conference Proceeding
Language:English
Subjects:
Capacitance
Capacitors
Dielectrics
Drives
Micromechanical devices
Q factor
Springs
Tuning
Voltage
Voltage-controlled oscillators
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Summary:This paper reports a MEMS tunable capacitor with a new actuation principle. The new design adopts electrostatic actuation of an electrically floating movable dielectric. This enables us to achieve a high Q factor by eliminating the loss associated with springs in the RF signal path. Also, the design can achieve a high tuning range, by using additional actuation combs and thus eliminating the pull-in effect. Since no DC bias is applied on the plates of variable capacitor, the parallel plates 1/3 gap limitation does not apply. The designed devices were fabricated in a SOI MEMS process, with a 25 ¿m thick device layer and minimum gap of 2 ¿m. Measurement results show that the tunable capacitor has a 135 fF initial capacitance with a tuning range of 367% and a Q factor of 56 at 1 GHz by bidirectional actuation.
ISSN:1930-0395
2168-9229
DOI:10.1109/ICSENS.2009.5398334