在GSM以及WLAN的共存通訊系統中，假使直接採用兩個震盪的訊號源，我們將會需要兩個震盪器，這會造成晶圓面積的消耗以及增加成本，因此結合可產生這兩種頻率的震盪器在一個可重組式的結構上是我們的目標。在成本的考量上，如果我們可以整合兩種不同頻帶的震盪器在單一晶片上，我們可以有效減少晶片面積消耗和降低成本。然而在射頻積體電路的設計中，電磁干擾會引起嚴重的問題。所以克服電磁雜訊的干擾是相當重要的。
在本論文中，我們將GSM和WLAN所需要的震盪頻率設計在其雙倍頻處，並借由可切換式電感來使頻率在3.6 GHz和4.8 GHz做切換，我們使用TSMC 0.18 um的製程技術來實現這各電路。
本論文有兩個創新的想法：第一是使用切換式電感做頻率的切換，我們將震盪頻率設計在GSM以及WLAM的雙倍頻處，並將使用一個除二電路來降低相位雜訊。另外一個是結合GSM以及WLAN系統在單一可重組式的結構上。

For the GSM and WLAN coexistence communication system, if we adopt these two oscillation signals directly, we need two oscillators. The chip area consumption is increased and thus the cost. So to combine these two oscillators into a reconfigurable structure is our goal. For the cost consideration, if we can integrate these two oscillators into a circuit, we can reduce the area consumption and the cost effectively. However, in the radio frequency integrated circuit design, electromagnetic interference (i.e. noise) causes serious problem. So to overcome the noise is important.
In this thesis, we double the oscillation frequencies of the GSM/WLAN coexistence oscillator circuit, by utilizing a switchable inductor to switch the frequency between 3.6 GHz and 4.8 GHz. We use TSMC 0.18 um technology to realize the circuit design. There are two innovative ideas in this thesis: one is to use switchable inductor used for the frequency switching. The oscillation frequency is doubled and than we can make use of the frequency divider to reduce the phase noise. Another idea is to achieve the combination of GSM and WLAN oscillators into a reconfigureable structure.

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