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28th July 2009, 06:23 #1
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hspice find propagation delay of a gate
hi,
Sorry, if this is the wrong place to ask, pls redirect me to the right place. i am very much new to this forum.
The problem is that, i am simulating a simple full adder in hspice for 1000 random inputs, and want to measure the propagation delay of each gate in the full adder for every input.
Iam not able to write the measure statements with particular rise and fall numbers to measure the delay.
Are there any postprocessing tools which will help me in doing that ?
I am very much new to this stream, pardon me if the questions sound too naive :)
Thanks in advance,
Phani

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28th July 2009, 13:46 #2
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how to calculate propagation delays of a circuit
Originally Posted by phanidee
What you should use in such case, is STA (Static Timing Analysis). For a starter on this method, see here.

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28th July 2009, 14:02 #3
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calculate propagation delay of a gate
yes, i want to calculate the single gate delays of all the gates involved.
i thought this could just be done with some commands in hspice.

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28th July 2009, 14:59 #4
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xor gate schematic
Originally Posted by phanidee
With a 16bit or a 32bitfulladder, however, there are so many (thousands) of possible paths, that it won't be easy to find out the longest path just by checking the schematic, i.e. you'd have to run hundreds or even thousands of simulations (and you'll never be sure if you really had found the longest path).
The STA method finds the longest propagation path very quickly, telling you also the single delays of the involved gates.

8th August 2009, 20:33 #5
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hspice measure propagation delay
i just want to calculate the propagation of 1 xor gate in 2nd full adder in a 16bit ripple carry adder. I would like to take the average of the propagation delays for 1000 inputs 10 16 bit ripple carry adder. so to calculate just this prop. delay of the xor gate i am not able to write the exact rise and fall numbers for 1000 inputs.
is there any way to get out of this problem ?

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9th August 2009, 13:57 #6
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how to measure delay propogation with hspice
Originally Posted by phanidee
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