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GATE 2019 EE – Question 16

Analog and Digital Electronics · Amplifiers: biasing, equivalent circuit and frequency response · 1 mark · Multiple choice

A system transfer function is $H(s)=\dfrac{a_1s^2+b_1s+c_1}{a_2s^2+b_2s+c_2}$. If $a_1=b_1=0$, and all other coefficients are positive, the transfer function represents a

  1. low pass filter
  2. high pass filter
  3. band pass filter
  4. notch filter

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Show answer and explanation

Correct answer: (A) low pass filter

Explanation

With $a_1=b_1=0$ the transfer function is $\frac{c_1}{a_2s^2+b_2s+c_2}$. It has a finite DC gain $\frac{c_1}{c_2}$ and falls to zero at high frequency, so it is a low-pass filter.