61. What is the term used to describe the range of an A/D converter for bipolar signals?
A. Full scale
B. FSR
C. Full-scale region
D. FS
Answer: B
The term Full-scale range (FSR) is used to describe the range of an A/D converter for bipolar signals (i.e., signals with both positive and negative amplitudes).
62. What is the term used to describe the range of an A/D converter for uni-polar signals?
A. Full scale
B. FSR
C. Full-scale region
D. FSS
Answer: A
The term Full scale (FS) is used to describe the range of an A/D converter for uni-polar signals
63. What is the fixed range of the quantization error eq(n)?
A. \(\frac{\Delta}{6}\) < e<sub>q</sub>(n) ≤ \(\frac{\Delta}{6}\)
B. \(\frac{\Delta}{4}\) < e<sub>q</sub>(n) ≤ \(\frac{\Delta}{4}\)
C. \(\frac{\Delta}{2}\) < e<sub>q</sub>(n) ≤ \(\frac{\Delta}{2}\)
D. \(\frac{\Delta}{16}\) < e<sub>q</sub>(n) ≤ \(\frac{\Delta}{16}\)
Answer: C
The quantization error eq(n) is always in the range \(\frac{\Delta}{2}\) < eq(n) \(\frac{\Delta}{2}\), where Δ is quantizer step size.
64. If the dynamic range of the signal is smaller than the range of the quantizer, the samples that exceed the quantizer are clipped, resulting in a large quantization error.
A. True
B. False
Answer: B
If the dynamic range of the signal, defined as Xmax-xmin, is larger than the range of the quantizer, the samples that exceed the quantizer range are clipped, resulting in a large (greater than Δ2 quantization error.
65. What is the relation defined by the operation of quantizer?
A. xq(n) ≡ Q[x(n)] = \(\hat{x}_k\)
B. xq(n) = Q[x(n)] = \(\hat{x}_k\), if x(n) ∈ Ik
C. xq(k) ≡ Q[x(k)] =\(\hat{x}_k\)
D. none of the mentioned
Answer: B
The possible outputs of the quantizer (i.e., the quantization levels) are denoted as (hat{x}_1, hat{x}_2,…hat{x}_L). The operation of the quantizer is defined by the relation, xq(n) ≡ Q[x(n)]= (hat{x}_k), if x(n) ∈ Ik.
66. What is the step size or the resolution of an A/D converter?
A. Δ = (R)/2(b+1)
B. Δ = (R)/2(b-1)
C. Δ = (R)/3(b+1)
D. Δ = (R)/2
Answer: A
The coding process in an A/D converter assigns a unique binary number to each quantization level.
If we have L levels, we need at least L different binary numbers. With a word length of b + 1 bits, we can represent 2b+1 distinct binary numbers. Hence we should have 2(b+1) > L or, equivalently, b + 1 > log2 L.
Then the step size or the resolution of the A/D converter is given by
Δ = (R)/2(b+1), where R is the range of the quantizer.
67. In the practical A/D converters, if the first transition may not occur at exactly + 1/2 LSB, then such kind of error is known as ____________
A. Scale-factor error
B. Offset error
C. Linearity error
D. All of the mentioned
Answer: B
In the practical A/D converters, if the first transition may not occur at exactly + 1/2 LSB, then such kind of error is known as an Offset error.
We note that practical A/D converters may have offset error (the first transition may not occur at exactly + 1/2 LSB.
68. In the practical A/D converters, if the difference between the values at which the first transition and the last transition occur is not equal to FS – 2LSB, then such error is known as _________
A. Scale-factor error
B. Offset error
C. Linearity error
D. All of the mentioned
Answer: A
In the practical A/D converters, if the difference between the values at which the first transition and the last transition occur is not equal to FS – 2LSB, then such error is known as Scale-factor error.
We note that practical A/D converters scale-factor (or gain) error (the difference between the values at which the first transition and the last transition occur is not equal to FS — 2LSB.
69. In the practical A/D converters, if the differences between transition values are not all equal or uniformly changing, then such error is known as?
A. Scale-factor error
B. Offset error
C. Linearity error
D. All of the mentioned
Answer: C
We note that practical A/D converters have linearity error (the differences between transition values are not all equal or uniformly changing).
