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Phase Response



Definition. The phase response $ \Theta(\omega)$ of an LTI filter is defined as the phase (or angle) of the frequency response $ H(e^{j\omega T})$:

$\displaystyle \zbox {\Theta(\omega) \isdefs \angle H(e^{j\omega T})} $

The phase response is often referred to as the ``phase'' of the filter. For real filters (filters with real coefficients), the filter phase can be defined unambiguously as the phase of its frequency response. The real-valued phase response $ \Theta(\omega)$ gives the phase shift in radians that each input component sinusoid will undergo.
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Polar Form of the Frequency Response
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Amplitude Response