Silicon-Micromachined Liquid Crystal Variable Capacitors for Tunable RF Devices

This paper presents the design and fabrication of a silicon-micromachined variable capacitor based on nematic liquid crystal (LC). The LC material is encapsulated in a thin micromachined housing, and its dielectric properties are controlled electronically. The chip capacitor can be used in a wide ra...

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Bibliographic Details
Main Authors: Kianmehr, Hassan, Mansour, Raafat R.
Format: Conference Proceeding
Language:English
Subjects:
analog variable capacitor
Capacitance
Capacitors
liquid crystal (LC)
micromachined capacitor
Power demand
Q-factor
Radio frequency
Semiconductor device measurement
variable capacitor
Voltage measurement
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Summary:This paper presents the design and fabrication of a silicon-micromachined variable capacitor based on nematic liquid crystal (LC). The LC material is encapsulated in a thin micromachined housing, and its dielectric properties are controlled electronically. The chip capacitor can be used in a wide range of RF reconfigurable applications that require analog tuning. Measurement and simulation results are presented for the chip LC variable capacitor. It exhibits a measured quality factor ranging from 44-123 at 1 GHz. Biasing voltage ranging from 0 V to 40 V results in a measured capacitance change of 18% for the fabricated micromachined capacitor. The devices are fabricated using an in-house multi-layer microfabrication process. An ion beam irradiation system is employed for the treatment of the pre-alignment layer. To our knowledge, this is the first time a chip LC-based variable capacitor has been demonstrated.
ISSN:2576-7216
DOI:10.1109/IMS37964.2023.10187908