超低電壓系統單晶片內嵌式非揮發記憶體之低電壓電子幫浦

Low-Supply Voltage charge-pump circuit for embedded non-volatile memory of ultra low-voltage SoCs.

呂易倫(Yi-Lun Lu)

指導教授 ： 張孟凡

國立清華大學/電機資訊學院/電機工程學系/碩士(2010年)

摘要

近年來可攜式裝置蓬勃發展，影音播放、數位相機乃至於智慧型手機與平板電腦等，此類裝置因為不會一直處於電源供應狀態，因此非揮發記憶體被廣泛地使用在此一領域。目前的系統單晶片中，內嵌式非揮發性記憶體需要高電壓使電子進入懸浮閘極以及大電流以完成寫入機制，而電子幫浦普遍被用在電路內部產生一個比供應電源更高的正電壓或更低的負電壓。
隨著CMOS製程技術的進步，電壓供應越來越低，但因耐用度問題所以所需的高壓無法隨之下降，另外可攜式裝置的使用時間是一大重點，若能使用綠色能源更是未來趨勢，而降低操作電壓至0.5V可符合這些需求。傳統電子幫浦在低供應電壓下無法提供足夠的高壓，輸出電流以及操作速度亦隨之下降而面積卻又隨之上升，均無法滿足前述需求。在本篇論文中，應用最常被使用的高電流傳遞之四種相位時脈控制機制，我們提出了不同的架構，並混和高壓與一般邏輯製程，先用時脈幫浦在0.5V操作電壓下產生一個1V的第一階高壓，透過電壓位移器後產生較大振幅的時脈提供給主幫浦使用，並藉由1V以下全部都可使用一般邏輯製程來縮小面積。
低電壓電子幫浦使用了九十奈米互補式金氧半導體製程技術實現，量測結果顯示可操作在0.5V甚至更低的操作電壓便可達到相同的輸出，而且若操作在相同電壓下，更可以節省百分之十五的面積。而且操作在低壓時的速度幾乎跟傳統在1V時的速度相同，完全達到原先設定的目標。

關鍵字

低電壓 ； 低功率 ； 零點五伏 ； 電子幫浦

並列摘要

In recent years, portable devices such as media player, digital camera, smart phone, and tablet, are developed greatly. Non-volatile memories are used generally because these devices are not always turned on. Embedded non-volatile memories require a high voltage to attract electrons into the floating gate and an enough current to finish program operation in recent SoCs. Charge pump circuit is used in these chips to generate the high voltage.
The supply voltage becomes lower and lower with more advanced process, but the high voltage can’t decrease because of endurance. Besides, the operating time is a very important specification for portable devices and using green power is the trend in future. Reducing supply voltage to 0.5V can fit these requirements. Traditional charge pumps can’t generate enough voltage and current and become slow and large at low supply voltage. In this work, we propose different structure and use hybrid devices with four-phase clock signals. The proposed circuit generates the first boosted voltage by clock pump and provides pumped clocks to main pump through level shifters. ALL blocks except main pump can use standard devices to reduce area because the first boosted voltage is only 1V.
The low voltage charge pump was fabricated in UMC 90nm 1P9M process. It can meet the same specification at 0.5v supply voltage by measuring result. The structure can save about 15% area at the same voltage. Its speed at low voltage is almost equal to traditional pump at 1V. ALL of our goals are achieved.

並列關鍵字

low voltage ； low power ； 0.5V ； charge pump

參考文獻

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