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GATE 2016 EC (EC3) – Question 46

Networks, Signals and Systems · Discrete-time Signals · 2 marks · Multiple choice

The direct-form FIR filter shown can be used to approximate a

Diagram for GATE 2016 EC (EC3) question 46
  1. low-pass filter
  2. high-pass filter
  3. band-pass filter
  4. band-stop filter

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Show answer and explanation

Correct answer: (C) band-pass filter

Explanation

The diagram subtracts the two-sample delayed branch from the direct branch: $y[n]=5x[n]-5x[n-2]$. Hence $H(e^{j\omega})=5(1-e^{-j2\omega})=10je^{-j\omega}\sin\omega$.

Its magnitude is $10|\sin\omega|$, zero at DC and at π, and maximal at π/2. It passes middle frequencies and rejects both extremes. Thus it approximates a **band-pass filter, C**.

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