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Title: | 可程式化三角波調變的展頻時脈產生器 A Spread Spectrum Clock Generator For SATA With Programmable Triangular Modulator |
Authors: | "Chia-Tseng ,Chiang" 江家增 |
Advisor: | 曹恆偉 |
Keyword: | 展頻時脈產生器,可程式化三角波調變器,上下數計數器,電磁干擾,整數-N頻率合成器, Spread Spectrum Clock Generator,programmable triangular generator,Up/Down counter,Electro-Magnetic Interference,integer-N frequency synthesizer, |
Publication Year : | 2009 |
Degree: | 碩士 |
Abstract: | 隨著高速數位存取介面迅速的發展,連接主要裝置與外部裝置的高速串列式連結越來越受歡迎,例如Serial AT Attachment (SATA)是最先進的外部儲存介面之一,傳輸速率已經高達3Gbps以上,在不久將來更會達到6Gps。但伴隨愈高速的傳輸速率,訊號會帶來更嚴重的電磁干擾。因此SATA系統需要能以調變頻率30KHz ~33KHz向下展頻5000ppm來降低電磁干擾。
展頻是一種犧牲訊號的完整性來降低電磁干擾的特殊技巧。因為電磁干擾與時脈抖動(jitter)是一個取捨的關係,因此本論文提出一個特別的方法能降低電磁干擾效應且能兼顧時脈完整性的展頻時脈產生器(spread spectrum clock generator,SSCG)。除了在頻域的電磁干擾衰減量,考慮展頻時脈在時域上所造成的影響才是更重要的部分因為在串列資料傳輸的過程中訊號在時域上的完整性是非常重要的議題。 我們使用互補式金氧半電晶體0.18μm的製程來設計晶片,本論文提出一個具有可程式控制展頻量的展頻時脈產生器,此技術是利用儲存在上下數計數器的數位資料來控制展頻量,而上下數計數器的時脈是由一低頻的整數-N頻率合成器來提供,使得調變頻率可維持在一個定值,因此我們可依系統需求來動態地調變展頻量使得在電磁干擾與時脈抖動之間可得一組最佳的值。 As external storage devices are widely used, high-speed serial links connection host and external devices are becoming popular. Serial AT Attachment (SATA.) is one of the most promising technologies providing large bandwidth up to 3Gb/s with possible extension to 6Gb/s in the near future. As operating a high speed data rate, currents and voltages present in the circuit and the signal traces lead to great Electro-Magnetic Interference (EMI), Therefore, SATA systems require a wide spreading of 5000ppm and a 30~33KHz modulation rate to reduce EMI. Spread spectrum is a special frequency modulation technique, which is sacrificed the signal integrity of the clock to reduce the EMI. In this thesis, we proposed a novel spread spectrum clock generator (SSCG) to release the trade-offs between the jitter performance and the amount of EMI reduction for SATA appications. Besides considering the amount of EMI peak reduction in frequency-domain, it is more important to take care of the impact in time-domain for SSCGs since the signal integrity in time-domain is a very significant issue for serial data transmissions. This chip is implemented in the process of 0.18um CMOS. In chapter 4 we proposed a programmable triangular generator technique for SSCG (Down spread 2500ppm~ 5000ppm). The technique utilizes the digital data stored in up/down counter to control the spread spectrum amount. An integer-N frequency synthesizer (low frequency) supplies the up/down counter clock to maintain the modulation frequency. Therefore we can adjust spread spectrum amount dynamically to achieve an optimal value between EMI reduction amount and the performance of jitter. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/25992 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 電子工程學研究所 |
Files in This Item:
File | Size | Format | |
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ntu-98-1.pdf Restricted Access | 4.77 MB | Adobe PDF |
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