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How to generate a clock signal with random noise in Cadence Spectre?

I am trying to generate a clock signal with random noise, but not using complicated VCO models in Cadence Spectre.

One possible way I think is to use the vsource in analogLib with "prbs" type, and specify the bit file with "...0101..." pattern. So that, I can put the noise for the pattern as provided by the vsource model.

But I don't know how to construct the bit file. Could someone please explain how to do it by steps or direct me to some reference?

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Andrew Beckett over 10 years ago

Simpler would just be to specify seed and taps, and specify (say) both as 2. This will give you a regular square wave source, and you can then give the RJ to add random jitter. Here's the edit properties form for vsource in this mode:
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Andrew Beckett over 10 years ago

Simpler would just be to specify seed and taps, and specify (say) both as 2. This will give you a regular square wave source, and you can then give the RJ to add random jitter. Here's the edit properties form for vsource in this mode:
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cADEUser over 5 years ago in reply to Andrew Beckett

How do make the clock 25% duty cycle. I am looking for creating 25% duty cycle ( or a certain High pulse width ) clock where I can add random and deterministic jitter.
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Andrew Beckett over 5 years ago in reply to cADEUser

As I'm forever saying, please read the forum guidelines as these politely ask you not to post on the end of very old threads as it makes it much harder for somebody to find a relevant answer later.

Anyway, in this case I'd suggest you use a "bit" source (the Source Type being bit):

I've used the Rise Delay to allow the duty cycle to be altered - this is using two ADE variables - one for the period of the clock, and the second (DUTY) which is the duty cycle as a percentage (so 25 for 25%). The bit pattern is 01 to generate a regular clock train, with -1 as the number of repetitions (any negative number means continuously repeating). Then because it's a bit source, you can enter the jitter parameters for both random and periodic (deterministic) jitter.

It would be good if this was possible for a pulse source, but right now it isn't - however, it's easy enough to implement using a bit source.

Regards,

Andrew.
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