Amplitude Response

Definition. The amplitude response $G(\omega)$ of an LTI filter is defined as magnitude (or complex modulus) of the filter frequency response $H(e^{j\omega T})$, i.e.,

$$\zbox {G(\omega) \isdef \left\vert H(e^{j\omega T})\right\vert.}$$

The amplitude response is also often called the magnitude frequency response.

The real-valued amplitude response $G(\omega)$ specifies the amplitude gain that the filter provides at each frequency.