State-Space model is supported.

Calculate this equation with given A/B/C/D matrix using built in 4-degree
rungekutta.

Calling Procedure ;.

$runge_kutta("File Name",mode,Input_RealArray,Output_RealArray,[X])G |

- File contains text coefficient for A/B/C/D.
- mode must be 0 at initial statement others(always) should be 1
- Give input vector
with Input_RealArray.**u** - Output_RealArray will get
result.*y* - Internal State X can be defined in HDL source as an option.

See example source of "bessel.vtakprj".

It simulates digital FM-Demudulator as below.

Fig. below shows typical analog pll block diagram.

Loop Filter transfer function is calculated per following equations.

Since Veritak Linear Simulator needs State-Space model, we must change
the equation to State Space model. .

Matlab or Scilab can do this by **tf2ss**.

Following is an example.

C2=14e-12 C1=100e-12 R1=4.7e3 R1C1=R1*C1; C1_C2=C1+C2; C1C2R1=C1*C2*R1; b=[R1C1 1]; a=[C1C2R1 C1_C2 0]; [A,B,C,D] = tf2ss(b,a) freqs(b,a) save 'F:\samples\loop_filter.txt' A B C D -ascii -double |
---|

Load "pll_test.vtakprj"

It may be a good example to start mixed analog/digital simulation.

An example based on classic control theory is shown in http://www.sugawara-systems.com/opencores/pll/pll.htm

See also user contributed linear system simulator per following section, which has more generic approach with full source by C++.