VLSI Multiple Choice Questions on “Noise in MOS Devices”.
1. Noise in VLSI circuits mean:
A. Unwanted signals that arise due to vibration in the passive circuits
B. Unknown signal that limits the minimum signal level that a circuit can process with acceptable quality
C. Signal which undergoes distortion
D. All of the mentioned
Answer: B
Clarification: In VLSI circuits noise limits the minimum signal level that a circuit process with acceptable quality.
2. In probability Noise is described as:
A. Random function
B. Random process
C. Deterministic function
D. Deterministic process
Answer: B
Clarification: Noise is a Random Process.
3. Noise generated by independent devices are:
A. Correlated
B. Uncorrelated
C. Equal
D. None of the mentioned
Answer: b
Clarification: Noise generated by independent devices are uncorrelated, eg: noise generated from resistor is not similar to noise generated from transistor.
4. The 2 types of noise that the analog systems face during signal processing are:
A. Device electronic noise and environmental noise
B. Noise due to Vibration and electronic noise
C. Passive and active noise
D. None of the mentioned
Answer: A
Clarification: Device electronic noise and environmental noise affects signal processing of analog signals.
5. Thermal noise is generated from:
A. Resistor
B. Capacitor
C. Inductor
D. All of the mentioned
Answer: A
Clarification: Thermal noise is due to random motion of electrons in a conductor.
6. Thermal noise is generated from MOSFET by:
A. Conduction of charge carriers in the channel
B. Electric field across the gate and channel
C. Capacitance of the gate oxide
D. Substrate bias effect
Answer: A
Clarification: Thermal noise is generated due to conduction of charge carriers in the channel.
7. Thermal noise current in the MOSFET is proportional to:
A. Transconductance
B. Resistance
C. Gate voltage
D. None of the mentioned
Answer: A
Clarification: Noise current I^2 = 4kTygm.
8. Flicker noise is found in MOSFET at:
A. Gate and oxide interface
B. Gate oxide and silicon interface
C. Source and substrate interface
D. Drain and substrate interface
Answer: B
Clarification: The interface between Gate oxide and silicon substrate generates flicker noise.
9. Flicker noise originates due to:
A. Conduction in channel
B. Drain to Source voltage
C. Reduction in channel length
D. Dangling bonds
Answer: D
Clarification: Dangling bonds generate flicker noise.
10. The average power of flicker noise depends on:
A. Thickness of oxide
B. Cleanness of the oxide silicon interface
C. Voltage on oxide
D. Length of channel
Answer: B
Clarification: Depending on the Cleanness of oxide silicon interface flicker noise varies.
11. In the following graph the fc is called as:
vlsi-questions-answers-mos-noise-concept-q11″>
A. Cutoff frequency
B. Threshold frequency
C. Corner frequency
D. None of the mentioned
Answer: C
Clarification: None.
12. The following graph is a spectrum of which noise:
vlsi-questions-answers-mos-noise-concept-q12″>
A. Thermal noise
B. Gaussian Noise
C. Flicker noise
D. None of the mentioned
Answer: D
Clarification: None.
13. If VIH of the 2nd gate is lower than VOH of the 1st gate, then logic output 0 from the 1st gate is considered as:
A. Logic input 1
B. Uncertain
C. Logic input 0
D. None of the mentioned