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How to measure in picoseconds?

 

Hello everyone,is it possible to measure delay in picoseconds in spice error log ? If we can ,could anyone please say the process to it.
 

I think you need to give us more information about what you are trying to do. LTspice doesn't 'know' that a picosecond is a very short time,and it 'understands' femtoseconds, but not attoseconds.

On 2024-11-25 09:52, Gayathri Kummari via groups.io wrote:
Hello everyone,is it possible to measure delay in picoseconds in spice error log ? If we can ,could anyone please say the process to it.
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On 25/11/2024 10:52, Gayathri Kummari via groups.io wrote:
Hello everyone,is it possible to measure delay in picoseconds in spice error log ? If we can ,could anyone please say the process to it.
That depends on your schematic and how you set up the analysis.

The general principle is:

.MEAS T1 when V(in)=2.5
.MEAS T2 when V(out)=2.5
.MEAS Delay param T2-T1

--
Regards,
Tony
 

I have a schematic that is large and it is not possible to do t2-t1.
Actually I'm implementing conventional 4bit cla


On Mon, Nov 25, 2024, 4:05 PM Tony Casey via groups.io <tony=ritecom.com@groups.io> wrote:
On 25/11/2024 10:52, Gayathri Kummari via groups.io wrote:
Hello everyone,is it possible to measure delay in picoseconds in spice error log ? If we can ,could anyone please say the process to it.
That depends on your schematic and how you set up the analysis.

The general principle is:

.MEAS T1 when V(in)=2.5
.MEAS T2 when V(out)=2.5
.MEAS Delay param T2-T1

--
Regards,
Tony
 

On 25/11/2024 12:02, Gayathri Kummari via groups.io wrote:

I have a schematic that is large and it is not possible to do t2-t1.
Actually I'm implementing conventional 4bit cla

I'm afraid you will have a hard time convincing me why it isn't always possible to do T2-T1, provided you have two nodes, or more, in your circuit. The net names I used were examples, they could be anything. The ability to perform this measurement is not affected by the complexity of the circuit.

That's about as much as we can say, since you haven't uploaded your schematic.

--
Regards,
Tony
 

On Mon, Nov 25, 2024 at 04:52 AM, Gayathri Kummari wrote:
Hello everyone,is it possible to measure delay in picoseconds in spice error log ?
Do you require that the numbers printed in the SPICE Log must be in picoseconds, rather than seconds?
 
If so, add another .MEAS command to multiply the delay by 1e12 or 1T.
 
Example:
 
.MEAS T1 when V(in)=2.5    ;<-- Use your own node and values here
.MEAS T2 when V(out)=2.5    ;<-- Use your own node and values here
.MEAS Delay param T2-T1    ;<-- Prints the delay in Seconds
.MEAS Delay_ps param Delay*1e12    ;<-- Prints the delay in Picoseconds
 
The size of your schematic is irrelevant.  What kind of circuit you are making is irrelevant.  I don't know what is a "cla", but it should not matter.  Electrical signals are electrical signals.  You do need to apply your brain's skills to tell the .MEAS commands where to measure your signals.  If not at 2.5 V, then use whatever voltage you want it to be.
 
Andy
 
 

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