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標題: 類比濾波器設計
Analog filter circuit design
作者: 黃志發
huang, chfa
關鍵字: Gm-C;濾波器;analog filter;polyphase filter;主動多相位濾波器;截止頻率
出版社: 電機工程學系
本篇論文描述類比濾波器電路設計和實現。我們利用非運算放大器所構成的緩衝器作為高速濾波器的電路架構,實驗結果證實此架構在我們我量測到的頻率可以到達200Mhz左右,除此之外,我們也實現了一個以GaAs HBT 製程的Gm-C濾波器電路,所用到的transconductance利用一比四的射極比達到了高輸入線性度,並且利用負電阻電路使得transconductance的輸出阻抗變大以利電流輸出。量測結果整個濾波器電路以串接方式實現了一個三階的Butterworth 濾波器而其截止頻率約為10Mhz 左右。類比濾波器除了串接之外也以LC ladder signal-flow 方式完成了整個電路的實現所以第五章我們利用一個rail-to-rail的Gm實現了一個五階的Elliptic 濾波器其截止頻率為1Mhz 左右適合基頻用低通濾波器.而在第六章我們將實現一個主動多相位濾波器電路藉以濾除通信系統中的鏡像訊號。有別於傳統的對稱的類比濾波器我們利用平移低通濾波器的方式達成了在IF 頻率時對IF訊號提供增益而對負頻率完成對鏡像訊號的濾除

This thesis described the design and implementation of analog filter design. We use non-opamp-based unity gain buffer to construct high-speed filter architecture. The experiment result show that we can arrive the cutoff frequency about 200Mhz.We also realize Gm-C filter with GaAs HBT technology. A high linear transconductance is used by 4:1 emitter ratio topology and we use negative resistance to improve the output impedance of transconductance. The measurement result show that we realize a 3rd order Butterworth filter by cascading method .The cutoff frequency is about 10Mhz.We also use LC ladder signal-flow to realize 5th order Elliptic filter, which is suit for baseband frequency application. The transconductance is realized in rail-to-rail topology. In the chapter six we will realize a polyphase filter to reject the image signal . The principle of a polyphase filter is different to symmetric analog filter .We use the transformation from LP to BP to realize the image rejection.
The measured results verify our design and implementation of analog filter . They also provide theory and implementation
Appears in Collections:電機工程學系所

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