Problem 1 (20 points):
#Q1. (3 points) A 14-bit analog-to-digital converter (ADC) has an input range of 1V to 6 V. If the output
of the ADC is 74, what is the voltage at its input? Ignore quantization error.
74× 6−1
...
Problem 1 (20 points):
#Q1. (3 points) A 14-bit analog-to-digital converter (ADC) has an input range of 1V to 6 V. If the output
of the ADC is 74, what is the voltage at its input? Ignore quantization error.
74× 6−1
214−1 +1=1.02258 V
#Q1. (3 points) A 12-bit analog-to-digital converter (ADC) has an input range of 2V to 5 V. If the output
of the ADC is 47, what is the voltage at its input? Ignore quantization error.
47× 6−15−2
212−1 +2= 2.0344 V
#Q2. (3 points) Briefly state the purpose of using voltage followers.
Used as a buffer between two stages since it has infinite input impedance and zero output impedance.
#Q3. (3 points) An analog signal contains three sinusoidal components with frequencies 5, 7 and 12 Hz.
What is the minimum sampling rate required in order to avoid aliasing?
24 sps
#Q3. (3 points) An analog signal contains three sinusoidal components with frequencies 5, 7 and 24 Hz.
What is the minimum sampling rate required in order to avoid aliasing?
48 SPS2
#Q4. (3 points) A6-bit ADC has an input range of 1 to 4.15 V. If the analog input changes by 82 mV over
two samples (which are between 2 to 3V), the estimated voltage after ADC will change by (circle one)
a) 25 mV or 50 mV
b) 100 mV or 150 mV
c) 50 mV or 100 mV
d) 20 mV or 40 mV
e) 40 mV or 60 mV
f) 50 mV or 75 mV
#Q4. (3 points) A6-bit ADC has an input range of 1 to 4.15 V. If the analog input changes by 108 mV over
two samples (which are between 2 to 3V), the estimated voltage after ADC will change by (circle one)
a) 25 mV or 50 mV
b) 100 mV or 150 mV
c) 50 mV or 100 mV
d) 100 mV or 120 mV
e) 40 mV or 60 mV
f) 50 mV or 75 mV
#Q5. (2 points) How many comparators are required to build a 3-bit direct conversion analog-to-digital
converter (ADC)? (circle one)
3 4 5 7 8
9 15 16 17 31
#Q5. (2 points) How many comparators are required to build a 4-bit direct conversion analog-to-digital
converter (ADC)? (circle one)
3 4 5 7 8
9 15 16 17 31
#Q6. (2 points) For a given input signal, if the sampling rate of an ADC is increased, the signal-to quantization-noise ratio (SQNR)(circle one)
a) must increase
b) must decrease
c) may or may not change
d) will not change
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