A Micro-Machined Parallel-Plate Tunable Capacitor with a Wide Tuning Range
- 詳細技術說明
- This new MEMS tunable capacitor perfectly meets those needs.
- *Abstract
-
Integrated wireless communications systems require tunable capacitors that have a wide tuning range, low loss, and monolithic integration. This new MEMS tunable capacitor perfectly meets those needs.
DESCRIPTION/DETAILS
This new technology is a MEMS tunable capacitor developed to meet the needs of integrated wireless communications systems. It can provide any potential tuning range by specification of the design and fabrication parameters. It exhibits low loss and can be integrated with any existing standard integrated circuit (IC).
How It Works
This technology eliminates the so-called "pull-in" effect, found in existing parallel-plate configurations, that limits their tuning range to 50%. Pull-in occurs when the space between the two parallel plates that make up the capacitor (see attachment: Figure 1a) is reduced by one-third. When the plates are moving together, the suspended plate will be attracted to the fixed plate and snap into contact with it. This creates a limit of 50% on the tuning range. The actual tuning range may be even lower due to parasitic capacitance.
By eliminating pull-in, this new technology creates a much wider tuning range.The pull-in effect is eliminated by a modification of the parallel plate design. The new tunable capacitor consists of three plates (Figure 1b, below), one is movable while the other two are fixed. The inner, fixed plate (E2) is used for variable capacitance, and the outer fixed plate (E3) is used for electrostatic actuation. The suspended top plate (E1) serves as the common ground for the two fixed plates. The spacing (d1) between the capacitance electrode (E2) and the suspended top plate (E1) is made smaller than the spacing (d2) between the actuation electrode (E3) and the suspended top plate (E1). The spacing between E2 and E1 can be reduced continuously and completely without the pull-in effect. This creates a fully controllable tuning range. (see attachment: Figure 1a & b)
Why It Is Better
As stated above, this technology eliminates the so-called "pull-in" effect, an intrinsic phenomenon existing in all current parallel plate configurations that limits their tuning range to 50%. This MEMS tunable capacitor technology eliminates the limitation of the "pull-in" effect and achieves a much wider tuning range without using complex design and fabrication process, which significantly enhances this technology's usefulness. In addition, this novel capacitor also provides lower interconnection- and parasitic-related losses than its metal-oxide semiconductor counterparts, and it is less complex due to its monolithic integration.
APPLICATIONS
- Wireless communications industry
BENEFITS
This MEMS tunable capacitor provides a wide tuning range that is needed in radio frequency (RF) communication applications. It also can be incorporated monolithically with other integrated circuits, and it exhibits a very low loss.
- This technology provides the wide tuning range, which is necessary for wide bandwidth communications.
- This technology produces very low loss (<0.1 dB) in high-frequency (5 GHz) applications.
- The fabrication of this MEMS capacitor is completely compatible with existing integrated circuit fabrication technology. This makes it especially useful for integrated wireless communication applications.
- This MEMS capacitor can achieve a higher quality factor as compared with its complementary metal-oxide semiconductor (CMOS) counterparts. This capacitor provides lower interconnection- and parasitic-related losses and is less complex due to its monolithic integration.
For more information about this technology, please contact the University of Illinois at Urbana-Champaign Office of Technology Management at otm@illinois.edu.
- *IP Issue Date
- None
- *IP Type
- Utility
- 國家
- United States
- 申請號碼
- 6418006
- 國家/地區
- 美國
