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DC value for VerilogA module

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ashrafsazid

ashrafsazid

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Hi could anyone please tell me how to set a dc value for a clock in Veriloga module?

I have a clock generation code. The DC value is zero. If I want to change the initial_begin value to set the desired DC then the phase is reversed. Is there any other mean to set the dc value seperately?

Code: 
parameter 	real	vdd = 1.8 ;
parameter	real	f_chop = 50k ;
parameter	real	tol = 1n ;
parameter 	real	ClkDelay = 0 ;
parameter 	integer	ChopEna = 1 ;
parameter	integer	offmode_Chop = 1 ;

@ (initial_step) begin
	period  = 1/f_chop;
	tgl1		= 1;
end

@(timer(ClkDelay, 0.5*period)) begin
	if (ChopEna>=1) begin
		if(tgl1==1) begin
			tgl1 = 0;
			end	else if(tgl1==0) begin
			tgl1 = 1;
		end 
end else if (ChopEna==0) tgl1 = offmode_Chop;
V(ChopClk) <+ transition(vdd*tgl1, tol, tol, tol) ;
end
 

ashrafsazid said:
The DC value is zero.
If I want to change the initial_begin value to set the desired DC then the phase is reversed.
Click to expand...
I can not understand what you want to mean at all.
Describe correctly.

Code: 
parameter real aho = -999.9;
real boke, kasu;

boke = transition(vdd*tgl1, tol, tol, tol);

if($abstime == 0.0)
  kasu = aho;
else
  kasu = boke;

V(ChopClk) <+ kasu;

BTW, you can not use your Verilog-A Module in Cadence Spectre PSS, since it has many hidden states.
 
Last edited:

You could certainly make the high and low levels into variables
along with the delay and duty cycle / width, and have complete
freedom pretty much.

Of course this could also be done to a vpulse analogLib source
and then you would have no surprises.
 

pancho_hideboo said:
I can not understand what you want to mean at all.
Describe correctly.
Click to expand...

dcval.JPG

This is the property table for a vpulse source.
I want to set the dc value for my verilog module as like this, so that I can change it based on the simulation (Red). In the meantime the clock transient behavior will remain same (Blue).
 

ashrafsazid said:
This is the property table for a vpulse source.
I want to set the dc value for my verilog module as like this,
so that I can change it based on the simulation (Red).
In the meantime the clock transient behavior will remain same (Blue).
Click to expand...
Answer is
Code: 
parameter real aho = -999.9;
real boke, kasu;

boke = transition(vdd*tgl1, tol, tol, tol);

if($abstime == 0.0)
  kasu = aho;
else
  kasu = boke;

if(analysis("dc", "static"))
  V(ChopClk) <+ aho;
else
  V(ChopClk) <+ kasu;
 
Last edited:

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