- 學位論文
應用於聲頻帶之一伏特二階三角積分調變器
1-V 2nd-Order Sigma-Delta Modulator for Voice Band Applications
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摘要
半導體工業協會(Semiconductor Industry Association)預測，在2004年時MOS電晶體供給電壓設計將低於1.2伏特，且低於0.9伏特於2008年。然而電晶體必須保持其臨限電壓在0.7伏到0.9伏之間以防止額外的漏電流產生。MOS電晶體在低電壓工作時(如1伏特)，數位電路方面仍然可以達到合乎預期的效能結果，但類比電路卻不是如此。因此，低功率和低電壓類比電路解決方案變成相當重要的要素以來發展未來的單晶片系統。 交換電容電路能提供類比系統高精準和低失真效能。除了研究低電壓交換電容電路之效能之外，本論文設計一個低電壓的2階低通三角積分調變器(Lowpass Sigma-delta Modulator), 可應用於聲頻應用上,此調變電路接上Decimator Filter即可組成完整的類比數位轉換器。為了可攜帶性的考量,而電池的選取對於可攜帶性產品是很重要的, 本調變器僅使用單端電源1-V,可有效降低電池重量,使用於有輕便性要求的產品上。本調變器使用全差動交換式電容電路(Switched-capacitor)的電路來實現,信號頻率為4 KHz,此頻率為一般的人類聲音頻率。在超取樣率為128時,目標解析度為10-bit,功率消耗小於200uW。
並列摘要
As predicted by the Semiconductor Industry Association, MOS transistors are required to operate in less than 1.2V by 2004 and 0.9V by 2008, while their threshold voltage are kept more or less unchanged (Vt 0.7V~0.9V) to avoid excessive leakage current. At low-voltage operation (as low as 1V), digital circuit can still attain reasonable performance, but most of the analog circuits even do not function. As a result, low-power and low voltage analog circuits solutions become essential to the development of single-chip systems in the near future. Switched-Capacitor (SC) circuits achieve high precision and low distortion for analog system. While studying the effect of low-voltage on the SC circuits, in this work, we design and implement a low-voltage 2nd-order lowpass sigma-delta modulator for voice applications. The modulator uses a single power supply (1-V), which can be provided by a single battery. The modulator will be implemented with switched-capacitor technique. The signal band is at 4 KHz for voice applications. The oversampling ratio is 128 and the resolution is about 10-bit. The power dissipation is lesser than 200uW.
參考文獻
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