1. What is the region between origin and the passband frequency in the magnitude frequency response of a low pass filter?
A. Stopband
B. Passband
C. Transition band
D. None of the mentioned
Answer: B
From the magnitude frequency response of a low pass filter, we can state that the region before passband frequency is known as ‘pass band’ where the signal is passed without huge losses.
2. What is the region between stopband and the passband frequencies in the magnitude frequency response of a low pass filter?
A. Stopband
B. Passband
C. Transition band
D. None of the mentioned
Answer: C
From the magnitude frequency response of a low pass filter, we can state that the region between passband and stopband frequencies is known as the ‘transition band’ where no specifications are provided.
3. What is the region after the stopband frequency in the magnitude frequency response of a low pass filter?
A. Stopband
B. Passband
C. Transition band
D. None of the mentioned
Answer: A
From the magnitude frequency response of a low pass filter, we can state that the region after stop band frequency is known as ‘stop band’ where the signal is stopped or restricted.
4. If δP is the forbidden magnitude value in the passband and δS is the forbidden magnitude value in the stopband, then which of the following is true in the passband region?
A. 1-δS≤|H(jΩ)|≤1
B. δP≤|H(jΩ)|≤1
C. 0≤|H(jΩ)|≤ δS
D. 1-δP≤|H(jΩ)|≤1
Answer: D
From the magnitude frequency response of the low pass filter, the hatched region in the passband indicates a forbidden magnitude value whose value is given as
1- δP≤|H(jΩ)|≤1.
5. If δP is the forbidden magnitude value in the passband and δS is the forbidden magnitude value in the stopband, then which of the following is true in the stopband region?
A. 1- δP≤|H(jΩ)|≤1
B. δP≤|H(jΩ)|≤1
C. 0≤|H(jΩ)|≤ δS
D. 1- δP≤|H(jΩ)|≤1
Answer: C
From the magnitude frequency response of the low pass filter, the hatched region in the stopband indicate a forbidden magnitude value whose value is given as
0≤|H(jΩ)|≤ δS.
6. What is the value of passband ripple in dB?
A. -20log(1- δP)
B. -20log(δP)
C. 20log(1- δP)
D. None of the mentioned
Answer: A
1-δP is known as the passband ripple or the passband attenuation, and its value in dB is given as -20log(1-δP).
7. What is the value of stopband ripple in dB?
A. -20log(1-δS)
B. -20log(δS)
C. 20log(1-δS)
D. None of the mentioned
Answer: B
δS is known as the stopband attenuation, and its value in dB is given as -20log(δS).
8. What is the passband gain of a low pass filter with 1- δP as the passband attenuation?
A. -20log(1- δP)
B. -20log(δP)
C. 20log(δP)
D. 20log(1- δP)
Answer: D
If 1-δP is the passband attenuation, then the passband gain is given by the formula 20log(1-δP).
9. What is the stopband gain of a low pass filter with δS as the passband attenuation?
A. -20log(1- δS)
B. -20log(δS)
C. 20log(δS)
D. 20log(1- δS)
Answer: C
If δS is the stopband attenuation, then the stopband gain is given by the formula 20log(δS).
10. What is the cutoff frequency of a normalized filter?
A. 2 rad/sec
B. 1 rad/sec
C. 0.5 rad/sec
D. None of the mentioned
Answer: B
A filter is said to be normalized if the cutoff frequency of the filter, Ωc is 1 rad/sec.
11. The low pass, high pass, bandpass, and bandstop filters can be designed by applying a specific transformation to a normalized low pass filter.
A. True
B. False
Answer: A
It is known that the low pass, high pass, bandpass, and bandstop filters can be designed by applying a specific transformation to a normalized low pass filter. Therefore, a lot of importance is given to the design of a normalized low pass analog filter.
12. Which of the following is true in the case of Butterworth filters?
A. Smooth passband
B. Wide transition band
C. Not so smooth stopband
D. All of the mentioned
Answer: D
Butterworth filters have a very smooth passband, which we pay for with a relatively wide transmission region.
12. What is the magnitude frequency response of a Butterworth filter of order N and cutoff frequency ΩC?
A. \(\frac{1}{\sqrt{1+(\frac{Ω}{Ω_C})^{2N}}}\)
B. \(1+(\frac{Ω}{Ω_C})^{2N}\)
C. \(\sqrt{1+(\frac{Ω}{Ω_C})^{2N}}\)
D. None of the mentioned
Answer: A
A Butterworth is characterized by the magnitude frequency response