voltage source whose duty cycle is random

[electronics20]

Dear all,
How to assign a voltage source whose duty cycle is random in HSPICE?
Many Thanks always for ur helps.

 

[dick_freebird]

Do you need true randomness, or simply random-appearing
/ time-varying? Because, after all, on a single SPICE run
you have no way of knowing which was used. Only some
statistical analysis will distinguish between true random
and pseudorandom, and you'd need a humongous sample
size.

That said, I have no answer for true random in-the-moment
sources (but you might look at tnoise). What I have done,
before, is stack a plurality of uncorrelated-frequency vsin
sources and feed that to a behavioral comparator, which
will then chatter in a random-enough-looking way.

 

[crutschow]

Are you looking for a fixed-frequency PWM signal with random duty-cycle?

Is there a random number (rand) function in HSpice?

 

[D.A.(Tony)Stewart]

THe Pseudo Random-Bit Generator Source or PRBS is defined in CHapter 5 of the manual

There are many variables based on Linear Feedback Shift Register (LFSR)

Certain comibinations of taps and length of shift register are chosen for "maximal length sequence" (MLS) YOu may only be concerned about short sequence length with 1% resolution from 1 to 99%, so a 7 bit MLS has adequate resolution.

For more details on LFSR and optimal tap values. https://www.maximintegrated.com/en/app-notes/index.mvp/id/1743

Keep in mind all LFSR's have one stuck initial state that will not work depending on if XOR feedback is positive or negative and that is all 1's or all 0's respectively, otherwise any seed can be used such as 50% or ....00001111...

 

[electronics20]

pseudorandom plz.