The pole-zero pattern of a certain filter is shown in the figure. The filter must be

The pole-zero pattern of a certain filter is shown in the figure. The filter must be Correct Answer High-pass type

According to the given pole zero pattern,

Transfer function is given by

H(s) = (s + j1) (s – j1) (s + j2) (s – j2)

= (s² + 1) (s² + 2²)

Now, at zero frequency, s = 0

H(0) = (0 + 1)(0 + 4) = 4

At infinite frequency, s = ∞

⇒ H(∞) = ∞

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