Need help in writing matlab function

[tompham]

Hi all
I am writing matlab code for PLL component. Below is my code:

function [C2,C1,R1] = PLLcom(ipump,vco_gain,fref,fout,bandwidth,phase_margin)

Kpd = ipump/2/pi; % phase detector gain
Kvco = vco_gain*2*pi; % vco gain
omega = 2*pi* bandwidth; % open loop bandwidth in radians/sec
N = fout/fref; % division ratio
pm = phase_margin*pi/180; %phase margin in radians/sec
%% Find T1 and T2
T1 = (sec(pm)-tan(pm))/omega;
T2 = 1/(omega*(sec(pm)-tan(pm)));
%% Solving for Loop Components
C2 = Kpd*Kvco/(N*omega^2)*T1/T2*sqrt((1+(omega*T2)^2)/(1+(omega*T1)^2));
C1 = C2*(T2/T1-1);
R1 = T2/C1;

The compile function shows no error. Why I can not get value of C1, R1?
I need someone to help me.
Thanks a lot

 

[milind.a.kulkarni]

Hi all
I am writing matlab code for PLL component. Below is my code:

function [C2,C1,R1] = PLLcom(ipump,vco_gain,fref,fout,bandwidth,phase_margin)

Kpd = ipump/2/pi; % phase detector gain
Kvco = vco_gain*2*pi; % vco gain
omega = 2*pi* bandwidth; % open loop bandwidth in radians/sec
N = fout/fref; % division ratio
pm = phase_margin*pi/180; %phase margin in radians/sec
%% Find T1 and T2
T1 = (sec(pm)-tan(pm))/omega;
T2 = 1/(omega*(sec(pm)-tan(pm)));
%% Solving for Loop Components
C2 = Kpd*Kvco/(N*omega^2)*T1/T2*sqrt((1+(omega*T2)^2)/(1+(omega*T1)^2));
C1 = C2*(T2/T1-1);
R1 = T2/C1;

The compile function shows no error. Why I can not get value of C1, R1?
I need someone to help me.
Thanks a lot

Hii....

Can you able to get value C2 at least...... Can you please also tell us what are the input parameters that you are passing to the function.......

Some coments on your coding -

First of all use the backets in your code like based on the forumla that you use-

Kpd = ipump/2/pi; % phase detector gain -> Kpd = ipump/(2/pi); % phase detector gain
or

C1 = C2*(T2/T1-1); -> should be either C1 = C2*((T2/T1)-1); or C1 = C2*(T2/(T1-1)); based on your formula....


Good luck

 

[tompham]

Hi kulkarni

Thanks for reply me and adding some comments.
This is some my input parameter:

%%ipump = 80e-6;
%%vco_gain = 510e6;
%%fref = 50e6;
%%fout = 800e6;
%%bandwidth = 5e6;
%%phase_margin = 56;

Thanks

 

[dave9000]

It's working for me, I get:
C2 = 7.899133602898353e-013
C1 = 7.660956439733713e-012
R1 = 1.359027078281924e+004

You have to call the function like this:
[C2,C1,R1] = PLLcom(ipump,vco_gain,fref,fout,bandwidth,phase_margin)

 

[milind.a.kulkarni]

Yes I do agree with dave9000

[C2,C1,R1] = PLLcom(ipump,vco_gain,fref,fout,bandwidth,phase_margin);
>> C2

C2 =

7.8991e-013

>> C1

C1 =

7.6610e-012

>> R1

R1 =

1.3590e+004
I am also getting the same output....

Good Luck

 

[tompham]

Hi kulkarni

Thanks for reply me and adding some comments.
This is some my input parameter:

%%ipump = 80e-6;
%%vco_gain = 510e6;
%%fref = 50e6;
%%fout = 800e6;
%%bandwidth = 5e6;
%%phase_margin = 56;

Thanks

---------- Post added at 15:56 ---------- Previous post was at 15:56 ----------

Thanks both of you

 

[Zardosht]

Hi
I need help to design vco,if you have some information please help me,i want to write a matlab code and i dont khnow how it work.
best.