# Bode plot: positive phase

1. Mar 4, 2012

### kandelabr

1. The problem statement, all variables and given/known data
I have a bode plot with a positive phase.

2. Relevant equations
this is a matlab code for the thing
Code (Text):
% bode phase plot
w = logspace(1, 4, 100);
G = 100*(1+0.017i*w)./(1i.*w.*(1+0.05i.*w).*(1+0.0025i.*w).*(1+0.001i.*w));
fi = atand(imag(G)./real(G));
semilogx(w, fi); % x-axis: log(omega*j), y-axis: phase in degrees
3. The attempt at a solution
Nothing to solve, there's just one thing I don't get: if phase means "relation between input and output signal", how can output signal come before the input?

Last edited: Mar 4, 2012
2. Mar 4, 2012

3. Mar 4, 2012

### Staff: Mentor

Keep in mind that the signals being compared are not starting from some t=0. They are a depiction of some steady-state relationship between theoretically eternal sinusoids, and as such can exhibit a relative phase shift.

4. Mar 5, 2012

### kandelabr

yeah, i thought this would be the explanation, and i neglected that bode plot is steady-state only.

thanks!