c6_pllsim.m

本程序是一个PLL仿真程序

% File: c6_PLLsim.m
w2b = 0; w2c = 0; s5 = 0; phivco = 0;   % initialize
twopi = 2*pi;   % define 2*pi
twofs = 2*fs;   % define 2*fs
G = 2*pi*fn*(zeta+sqrt(zeta*zeta-lambda));      % set loop gain
a = 2*pi*fn/(zeta+sqrt(zeta*zeta-lambda));      % set filter parameter
a1 = a*(1-lambda); a2 = a*lambda;   % define constants
phierror = zeros(1,npts);   % initialize vector
fvco = zeros(1,npts);
% beginning of simulation loop
for I = 1:npts
    s1 = phin(I)-phivco;    % phase error
    s2 = sin(s1);   % sin phase detector
    s3 = G*s2;
    s4 = a1*s3;
    s4a = s4-a2*s5;     % loop filter integrator input
    w1b = s4a+w2b;      % filter integrator (step 1)
    w2b = s4a+w1b;      % filter integrator (step 2)
    s5 = w1b/twofs;     % generate filter output
    s6 = s3+s5;         % VCO integrator input
    w1c = s6+w2c;       % VCO integrator (step 1)
    w2c = s6+w1c;       % VCO integrator (step 2)
    phivco = w1c/twofs; % generate VCO output
    phierror(I) = s1;   % build phase error vector
    fvco(I) = s6/twopi; % build VCO input vector
end
% end of simulation loop
freqerror = fin-fvco;   % build frequency error vector