Modelling a PLL in Verilog A/AMS

[netbug]

Dear all,

I am designing a behavioral model for a PLL. As I am new to this language, I have decided to start with the oscillator. I have just to copied and paste a piece of code that I found on Cadence's documentation.

The problem is that I get an error which I cannot solve.


Some lines of the code:

`include "constants.vams"
`include "disciplines.vams"

module oscillator(out);
output out;
electrical out;

parameter real freq=100 from (0:inf);
parameter real ratio=1 from (0:inf);
parameter real Vlo=-1, Vhi=1;
parameter real tt=0.01*ratio/freq from (0:inf);
parameter real fmJitter=0 from [0:0.1/freq);
parameter real pmJitter=0 from [0:0.1*ratio/freq);

.......

Error:

Error found by spectre during hierarchy flattening.
ERROR (SFE-1997): "input.scs" 51: I12: parameter `tt': Unknown parameter name `freq' found in expression.

But I think freq is correctly defined.

Thanks,
Pedro