| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 90 === Modern wireless systems require high quality voltage-controlled oscillators (VCOs) that exhibit wide tuning range and low phase noise in the several gigahertz frequency ranges. With the explosive development of micromachining technologies, the variable capacitors with high-Q factor and wide tuning range have been reported. However, packaging of these MEMS devices may accounts for 50-80 % of manufacturing cost. Therefore, a suitable packaging approach with low cost and ease of fabrication is desperately needed and thus facilitate micro devices into commercial realization. This paper demonstrates a novel and fully-packaged variable capacitor, and the micro cap is served as the packaging structure and top electrode at the same time which can protect the variable capacitor’s structure from the undesired physical attack and also enlarge the capacitor tuning range to 2:1. By taking advantages of micro cap technology, the subsequent procedures are able to utilize conventional I.C. packaging, minimizing changes with an addition of integrated MEMS devices. Furthermore, the vacuum sealing can also be achieved to reduce phase noise and alleviate the thermal, humid, and air damping effect. This approach is fully compatible with CMOS process and able to integrate micromachined variable capacitor and electric circuit into a single chip.
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