introduce jitter in cadence PLEASE HELP

Thread Starter

farid82

Joined Jan 15, 2012
8
Hi folks,

for a project I*m working I need a jittery square wave pulse to apply to input!
anyone know how to produce such a signal in cadence tool??

I'd be appreciated for any hint

regards
farid
 

Thread Starter

farid82

Joined Jan 15, 2012
8
Which Cadence tool? What type of design entry?
Dear Brownout,
you're right maybe I was not clear enough,

I working with cadence spectre ,and I have access to "ahdlLib" and "analoglib" libraries,

at the input of my design , I just need a square wave pulse with variation in rising edge of the signal .and I don't know how to produce it

I attached a photo a signal which I need to produce.
as u can see I need a pulse which rising edge of it start earlier or later than expected ,and its random, I mean some time the rising edge is as expected ,butt some time it starts a bit earlier or later.(which is called jiiter)

regards
farid
 

Attachments

Thread Starter

farid82

Joined Jan 15, 2012
8
Define jittery

I attached a photo a signal which I need to produce.
as u can see I need a pulse which rising edge of it start earlier or later than expected ,and its random, I mean some time the rising edge is as expected ,butt some time it starts a bit earlier or later.(which is called jiiter)

regards,
farid
 

Brownout

Joined Jan 10, 2012
2,390
Dear Brownout,
you're right maybe I was not clear enough,

I working with cadence spectre ,and I have access to "ahdlLib" and "analoglib" libraries,

at the input of my design , I just need a square wave pulse with variation in rising edge of the signal .and I don't know how to produce it

I attached a photo a signal which I need to produce.
as u can see I need a pulse which rising edge of it start earlier or later than expected ,and its random, I mean some time the rising edge is as expected ,butt some time it starts a bit earlier or later.(which is called jiiter)

regards
farid
Hi farid,

I dont' know anything about AHDL, but I've used verilog to do this before. Here is some code I copied from another discussion, to show how it was done.

// initialize
initial begin
force clk = 1'b0;
// wait for sometime...
#400;
// release forece
release clk;
end

always @()
clk <= #(period/2+$random(-jitter/2,jitter/2) ) ~clk;
The important part is in the last line. A function "$random" is added to the clock half-period to achieve the jitter. You might look into the AHDL documentation and see if there is a random function. I'll just bet there is. Let me know if you have any questions about the code.

Source: http://www.edaboard.com/thread100284.html
 

SgtWookie

Joined Jul 17, 2007
22,210
Use an ideal opamp or comparator.

Feed one input a sawtooth wave; one that rises to a maximum value and then suddenly drops; this will establish your base frequency.
Feed the other input a sine or triangle wave that is a different frequency from the sawtooth wave.
 
Top