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The 10% IR drop we talk about represents VDD drop+VSS drop?

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albred

albred

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I often read that 10% IR drop may cause 7% performance degrade..
Does the 10% mentioned here represents VDD drop+VSS drop? If so, what is the deffernt between 2%VDD/8%VSS and 5%VDD/5%VSS?
I'm not sure about the impact of VSS drop to output high voltage(CMOS, voltage pull up by VDD, seems irrelevant with VSS ).
 

Re: The 10% IR drop we talk about represents VDD drop+VSS dr

albred said:
I often read that 10% IR drop may cause 7% performance degrade..
Does the 10% mentioned here represents VDD drop+VSS drop? If so, what is the deffernt between 2%VDD/8%VSS and 5%VDD/5%VSS?
I'm not sure about the impact of VSS drop to output high voltage(CMOS, voltage pull up by VDD, seems irrelevant with VSS ).
Click to expand...

It does not make difference whether it is 2%vdd 8%vss or 10%vdd 0%vss etc because we would be looking at vdd - vss (difference) only. so, 10% IR drop means that vdd-vss has been decreased by 10%.

The high output is defined with respect to some reference in this case it is VSS. So, in case VSS gets increased due to IR drop then in that case output high though seems unaffected with respect to ground i.e. 0 volts, but has actually got decreased with respect to VSS.
 
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    albred

    albred

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Re: The 10% IR drop we talk about represents VDD drop+VSS dr

Thanks nitu.
I think you're righy.
 

Re: The 10% IR drop we talk about represents VDD drop+VSS dr

10% IR DROP means (VDD(drop) - VSS(drop)) = 90 * (VDD(ldeal) - VSS

(ideal)), that's all.

best regards




albred said:
I often read that 10% IR drop may cause 7% performance degrade..
Does the 10% mentioned here represents VDD drop+VSS drop? If so, what is the deffernt between 2%VDD/8%VSS and 5%VDD/5%VSS?
I'm not sure about the impact of VSS drop to output high voltage(CMOS, voltage pull up by VDD, seems irrelevant with VSS ).
Click to expand...
 

Re: The 10% IR drop we talk about represents VDD drop+VSS dr

IR drop is fall in VDD and rise VSS that means diference between fall in VDD and rise in VSS


EX : - 10%fall in VDD - 10%rise in VSS.
 

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