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kamesh419

Junior Member

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Posts: 25

The Pwl file is empty.
Mar 02^nd, 2005, 8:23am

Dear all,

I have modified many things compared to my last post. That is the reason i am posting a new thread.

The schematic that iam working on now is

http://www.cyd.liu.se/users/~kamva881/temp/circuit.jpg

I tried to simulate it. It gives me an error saying (This is a part of my output.log file)

Quote:

Simulating `raw/tb_DW01_add_cla_width8' on MYHOSTMACHINE at 4:45:30 PM, Wed Mar 2, 2005.

Notice from spectre during hierarchy flattening.
timeSweep: `stop' has the unusually large value of 100 s.
Error found by spectre during initial setup.
Waveform file
`/home/coworker/kameswar/glitches/SIMULATION/CADENCE/pwlFile5' is
empty.

spectre completes with 1 error, 0 warnings, and 1 notice.
spectre terminated prematurely due to fatal error.

But my pwlFile5 is not empty. a part of my pwlFile5 is as follows.

Quote:

v_B1 B<1> 0 pwl '0*(10n)' '3'
+, '0*(10n)+.3n' '3', '1*(10n)' '3'
+, '1*(10n)+.3n' '0', '2*(10n)' '0'
+, '2*(10n)+.3n' '0', '3*(10n)' '0'
+, '3*(10n)+.3n' '3', '4*(10n)' '3'
+, '4*(10n)+.3n' '0', '5*(10n)' '0'
+, '5*(10n)+.3n' '0', '6*(10n)' '0'
+, '6*(10n)+.3n' '0', '7*(10n)' '0'
+, '7*(10n)+.3n' '0', '8*(10n)' '0' ... ...... ... ..

I do not understand where the problem is. every thing that i do depends on this small test circuit which iam developing now. Plz help me.

Thanks in advance,
kamesh.

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Truth lies everywhere and partially even with the error.

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Ken Kundert Global Moderator Offline Posts: 2384 Silicon Valley	Re: The Pwl file is empty. Reply #1 - Mar 2^nd, 2005, 9:41am What you included in your waveform file is a netlist description of a PWL waveform. What Spectre expects in a waveform file is simple time-value pairs, and they must consist of simple numbers, not expressions. Thus, the file should contain something like the following. 0 3 10e-9 3 10.3e-9 0 20e-9 0 ... -Ken
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kamesh419

Junior Member

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Posts: 25

Re: The Pwl file is empty.
Reply #2 - Mar 2^nd, 2005, 10:14am

Thank you ken for the reply.

I know that your suggestion works. by using your method i get the digital wave form and not the analog one i believe. Modelling a digital waveform can also be done by using a simple verilog testbench instead of using vpwlf sources. But the problem is i cannot model the transitions from 1-->0 and from 0-->1, like using raising and falling times.

Can i make use of my netlist description of PWL waveform in any way so that i get the analog description of a wave and not a digital one ? or can i use your method to do this in any different way ?

Thanks in advance,
kamesh.

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Truth lies everywhere and partially even with the error.

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Ken Kundert Global Moderator Offline Posts: 2384 Silicon Valley	Re: The Pwl file is empty. Reply #3 - Mar 2^nd, 2005, 10:14pm The waveform I showed is a PWL waveform, so it does transition smoothly between specified values. In this case it takes 300ps to transition between levels. -Ken
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