close all;
clear all;
R1 =pi/4;
R2 =3*pi/4;
R3 = 0;
Fc=1.6e9;
Fd=40e3;
 
eta =sqrt(2)/2;
theta =2*pi*1/100;
Kp = ((4*eta*theta)/(1+2*eta*theta+theta^2)); % gain of a phase detector
Ki = ((4*theta^2)/(1+2*eta*theta+theta^2)); % gain  coefficient 
d_phi_1 = pi/2;
n_data = 100;
 
for nn =1:n_data
phi1= R1 +d_phi_1;
phi1_R(nn) = phi1;
 
s1 =exp(j*2*pi*(Fc+Fd+R1)); 
s2 =exp(j*2*pi*(Fc+Fd+R2));
A*cos(w1*t+w2*t
 
s1_R(nn) =s1;
s2_R(nn) =s2;
 
t =s1*conj(s2);
phi_error =atan(imag(t)/real(t))/(2*pi);
phi_error_R(nn) = phi_error;
sum1 =Kp*phi_error + phi_error*Ki+R3;
 
R1_R(nn) =R1;
R2_R(nn) = R2;
R1 =phi1;
 
R2=R2+sum1;
R3 =R3+phi_error*Ki;
phi2_R(nn) =R2;
end
 
figure(1)
plot(phi1_R);
hold on
plot(phi2_R,'r');
hold off;
grid on;
title('phase plot');
xlabel('Samples');
ylabel('Phase');
 
 
figure(2)
 
plot(phi_error_R);
title('phase Error of phase detector');
grid on;
xlabel('samples(n)');
ylabel('Phase error(degrees)');
 
 
figure(3)
plot(real(s1_R));
hold on;
plot(real(s2_R),'r');
hold off;
grid on;
title('Input signal & Output signal of VCO');
xlabel('Samples');
ylabel('Amplitude');
axis([0 n_data -1.1 1.1]);