隨著行動通訊電子產品的大眾化，行動通訊產品快速成長，為了讓產品讓使用者更方便使用，對產品輕薄短小以及成本降低極盡要求，而系統整合(SOC)正是可以滿足以上之要求，因此系統整合正是目前技術發展的趨勢。近年來矽半導體製程、電腦輔助設計軟體、以及電路設計技巧的進步，已讓數位與類比電路的整合度大大提高，反觀要把射頻電路做整合的話，仍有許多困難要克服，許多無法整合的高頻電路中，其中之一就是高頻濾波電路。由於矽基板是導電材料而造成損耗大，使得在矽基板上製作元件品質因素(Q 值)不高，如果濾波器Q 值不高會使濾波效果有限，造成頻譜選擇能力差，難以將濾波器整合。預將濾波器整合入矽基板，目前最有淺力方式之ㄧ是利用微機電系統製作，微機電系統即結合半導體製程技術及機械製作的概念，其將積體電路與機械元件製作於單一晶片上。透過機械結構的設計方式，可提供高元件的Q 值，而且能將複雜的電路簡化，以達到微小化和低成本的目的。本計劃的研究中，是利用0.18CMOS 製程與MEMS 後製程之結合，設計兩個可應用在WLAN 的濾波器，一個應用於WLAN 802.11b/g 頻率在2.4GHz 之帶通濾波器(Band-Pass Filters)，另一個應用在WLAN 802.11a，頻段在5.5GHz 之帶通濾波器，利用此技術達到濾波器整合度提高之目標。 With mobile communication products popularizing, the communication products expand speedily. For convenience to user, it is needed extremely to lighten and shrink the mobile productions. The system on a chip (SOC) is a solution to satisfy the need. Therefore, the SOC is a current trend of the development. In past years, silicon-base semiconductor process, computer-aided design tools, and circuit design skills have all made great progress, and it makes the high integration between digital and analog circuits. However, it is difficult to integrate with radio frequency (RF) circuits. One of those RF circuits is RF filter. Because silicon substrate is conductance material inducing large power loss and low quality factor (Q) of components. If the Q factor of RF-filter is low, the filter capability is limited. It makes bad selectivity of the filter bad and the filter is difficult to be integrated. To integrate with RF filter on a silicon substrate, on of the most potential solution is Microelectromechanical Systems (MEMS) Technology. The MEMS is the process that combines semiconductor engineering with mechanism engineering, and could fabricate integration circuits and mechanical components on a chip. By the mechanism design and fabrication, the Q factor of the components could be enhanced. Moreover, it could simplify the circuits to achieve the purpose of shrink and cost down. The proposal is expected to design and fabricate tow band-pass filters for WLAN application by the combination of 0.18μm CMOS process and its MEMS post-process. One of them is in the 2.4GHz frequency band for WLAN 802.11 b/g application. The other is in the 5.5GHz frequency band for WLAN 802.11a application. It is also expected to improve the integration of the RF filters.
