中文摘要
降低電壓是一個減少功耗非常有效的方法。然而，使用這個方法的其中一個壞處就是降低電路效能。在本篇論文裡，我們研究了多種不同的在次臨界區應用的低功耗電路和提出了一個基板偏壓插座電路以最佳化電路效能以及待機功耗。在可變動臨界電壓的金氧半電路裡可以藉由一個外部電路提供一個適當的基板偏壓，但是這也消耗了更多的功耗在對基板電容充放電。

使用基板偏壓插座的電路利用電荷分享的方法，使PMOS的基板電容對NMOS的基板電容充電來對基板偏壓，而不需使用外部的偏壓電路。它不必使用外部的偏壓電路來對基板電容充電，因此可以節省功耗。

當這個電路開啟時，NMOS和PMOS電晶體的基板電容將會分享它們的電荷，使得電晶體的效能提昇。以一個4位元的漣波進位家法器而言，我們發現它的效能比起一般CMOS電路可以提昇約26%。當插座關閉時，待機功耗只有比一般CMOS電路增加約2.3%。反觀，動態臨界電壓金氧半電路有較低的速度以及比起一般CMOS電路約增加500倍的待機功耗。此外，使用基板偏壓插座的方法有著較低的面積增加量。

在這篇論文裡，由於要取得更精準的效能以及待機功耗的估計，在N井區及P井區間的寄生電容電阻也需要小心的建造模型。我們相信增加這些模型，可以使得比較更有意義。

Voltage scaling has been shown to be an effective method to reduce power consumption. However, one of the penalties of this method is the reduction of circuit performance. In this thesis, we study various low power circuits operating in sub-threshold region and propose a body biasing socket circuit for performance and standby power optimization. The VTMOS circuit can give a proper body bias to the circuit with an external circuit, but it consumes more power to charge and discharge the body capacitance. Without the external biasing circuit, the circuit with body biasing socket uses the body sharing method to charge the NMOS body capacitance with PMOS body capacitance. It doesn’t bias the circuit by charging the body capacitance with external circuit and can save the power. This circuit, when turns on, shares the body charges of the NMOS and PMOS transistors and thus improves the transistor performance. For a simple 4-bit Ripple Carry Adder, we find the performance improved 26% as compared to the standard CMOS circuit. When the socket is turned off, the standby power is only 2.3% larger than the standard CMOS adder. In contrast the DTMOS (Dynamic Threshold MOS transistor) circuit has lower speed and with 500X larger standby power compared to the standard CMOS circuit. In addition, the area increases with the adder circuit is also much smaller with the body biasing socket method.
In this thesis, in order to get accurate performance and standby power estimation, the transistor body terminals and the N-well, P-well parasitics are also carefully modeled. We believe with these added models, the comparisons are more meaningful.

Reference
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