LOGIC WITH MULTIPLE THRESHOLD VOLTAGES
In the previous chapter timing slack has been used to reduce the dynamic power consumption of a logic block. With ongoing technology scaling, leakage power gains more and more importance. In mobile low-power systems with low activity profile, the standby power is often more important than the dynamic power consumption. Hence, slack can be used primarily to reduce leakage currents by using devices with an increased threshold voltage for the gates in subcritical paths. Regarding the alpha power delay model given by eq.1.2 one can see that this degrades the signal propagation delay, but according to eq. 1.5 the subthreshold current is lowered exponentially.
KeywordsThreshold Voltage Short Channel Effect Dynamic Power Consumption Subthreshold Current Standard Cell Library
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