Will local minimums and maximums of magnitude response of a real LTI system always correspond exactly to the phase angles of the zeroes and poles?

15 Views Asked by At

Will the normalized frequencies corresponding to the local minimums and maximums for the frequency magnitude response $|H(e^{j \omega})|$ of an linear and time-invariant system (with real-valued impulse response $h[n]$) always be exactly the same as the phase angles of the zeroes and poles of the system function $H(z)$ (i.e. Z-transform) of the LTI system?

If they do, please give a sketch of proof. If they don't, please give a counter example.

For example, if a zero (i.e. root) of the system function (i.e. Z-transform of the real-valued impulse response function) is $r_0*e^{j \omega_0}$ ($r_0\neq1$), then will $|H(e^{j \omega_0})|$ be a local minimum for the magnitude response function $|H(e^{j \omega})|$?

Similarly, if a pole of the system function is $r_0*e^{j \omega_0}$ ($r_0\neq1$), then will $|H(e^{j \omega_0})|$ be a local maximum of the magnitude response function?