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For example, There're 2 processors in which voltages of 1 signals are 1.0 volt. Manufacturer A make it so that 0.95+ to 1.00 volt is also considerd 1, while manufacturer B make the same processor recognize 0.9+ to 1.00 volt as 1. What is the trade off between the two?

Bonus question: Also, are there official names for 1-signal's voltage and 0-signal's voltage?

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    \$\begingroup\$ Vih and Vil are the terms often used in datasheets to specify the high and low level inputs. \$\endgroup\$ – Colin Aug 4 '17 at 8:13
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    \$\begingroup\$ What bonus do I get if I answer the second homework question? \$\endgroup\$ – Chu Aug 4 '17 at 10:24
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Typical trade-offs associated with higher \$V_{ih}\$ and \$V_{il}\$ margins are longer required setup and hold times. For example, the same chip which needs 5us to sample a voltage of 0.95V as logical "1" may require 7us to sample 0.9V.

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  • \$\begingroup\$ I don't quite understand, why does it take the chip longer to sample a lower voltage ? \$\endgroup\$ – Nhu Thai Sanh Nguyen Aug 4 '17 at 12:29
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Deciding the voltage level for processor execution is a complicated task. Reducing operating voltage leads to lower energy consumption (Power is proportional to voltage squared). On the other hand it leads to slower devices, one may visualise it as reduced current in a MOSFET. This in turn further leads to decrease in frequency of operation. Other factor which decided the frequency is the architecture. As you can see, there are various parameters that are taken into consideration while deciding the operating temperature. Hope the answer helps!

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    \$\begingroup\$ This doesn't address the OP's question. They aren't asking about the trade-off associated with lower operating voltage. They're asking about the difference in spec for Vih. \$\endgroup\$ – Daniel Aug 8 '17 at 16:48
  • \$\begingroup\$ In most of the highly reliable systems, operating voltage does not differ from Vih \$\endgroup\$ – Ayush Agrawal Aug 8 '17 at 16:57

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