HI

I think your out put is not full swing and also the loading capacitances are not chosen properly.

Majid Amini Valashani

Thanks for your comprehensive reply! I admit your descriptions.

But just at this part:

• the reported “Power” is
• "Power consumption of full-adder” + “Power consumption of input and output inverters”
• To overcome this problem, you should use 2 different supply voltages in your HSPICE code. One for full-adder and one for inverters."

Can you expand it? As far as I know it is possible to consider two different delays, but I dont know what do you mean about considering two supply voltages to obtain power consumption (although i think i have seen this case in another article too). I considered a total power for all test bed(3).

Thanks Mohammad Reza Reshadinezhad,

I considered Cload values by imitating other articles, in fact I do not know how to obtain their values in CNTFET-based circuits.

Majid Amini Valashani

Thank you very much! You have described clearly.

It is a maybe  heavy news for me  because I should simulate again all of my circuits, and you know, the CNTFETs have a long -time simulation.However thank you so much for sharing your knowledges with me.

Dear Madam,

This is a gate-level issue. You can expect issues like this in deep-submicron technology. What you see in the diagram, is that the propagation through the ripple chain of each full adder, slows down the slew rate of the signal. This is typical in deep submicron, where only the inverters and to a limited extend, the NAND2 gates are able to keep the slew rate of the propagating signals. All other gates tend to lose slew rate.

This issue should be prevented in logic synthesis. Logic synthesis should be done such that, the minimum slew rate is respected. (this is a logic synthesis constraint.)

Obviously, here it went wrong !. You should not debug this in simulation, but in logic synthesis, and in running timing check tools. So, the question to you obviously is:

(1.) How did you run logic synthesis ?. (If at all, if you did not, please do.)

(2.) What timing check tool did you use ?.

(3.) What minimum slew rate did you specify ?.

Best Regards,

Henri.