Multiple Choice Questions and Answers on VLSI Design & Technology
1) The utilization of CAD tools for drawing timing waveform diagram and transforming it into a network of logic gates is known as ________.
a. Waveform Editor
b. Waveform Estimator
c. Waveform Simulator
d. Waveform Evaluator
ANSWER: Waveform Editor
2) Which among the following is a process of transforming design entry information of the circuit into a set of logic equations?
a. Simulation
b. Optimization
c. Synthesis
d. Verification
ANSWER: Synthesis
3) _________ is the fundamental architecture block or element of a target PLD.
a. System Partitioning
b. Pre-layout Simulation
c. Logic cell
d. Post-layout Simulation
ANSWER: Logic cell
4) In VLSI design, which process deals with the determination of resistance & capacitance of interconnections?
a. Floorplanning
b. Placement & Routing
c. Testing
d. Extraction
ANSWER: Extraction
5) Among the VHDL features, which language statements are executed at the same time in parallel flow?
a. Concurrent
b. Sequential
c. Net-list
d. Test-bench
ANSWER: Concurrent
6) In Net-list language, the net-list is generated _______synthesizing VHDL code.
a. Before
b. At the time of (during)
c. After
d. None of the above
ANSWER: After
7) In VHDL, which object/s is/are used to connect entities together for the model formation?
a. Constant
b. Variable
c. Signal
d. All of the above
ANSWER: Signal
8) Which data type in VHDL is non synthesizable & allows the designer to model the objects of dynamic nature?
a. Scalar
b. Access
c. Composite
d. File
ANSWER: Access
9) Which type of simulation mode is used to check the timing performance of a design?
a. Behavioural
b. Switch-level
c. Transistor-level
d. Gate-level
ANSWER: Gate-level
10) In the simulation process, which step specifies the conversion of VHDL intermediate code so that it can be used by the simulator?
a. Compilation
b. Elaboration
c. Initialization
d. Execution
ANSWER: Elaboration
11) Which type of simulator/s neglect/s the intra-cycle state transitions by checking the status of target signals periodically irrespective of any events?
a. Event-driven Simulator
b. Cycle-based Simulator
c. Both a and b
d. None of the above
ANSWER: Cycle-based Simulator
12) Which among the following is not a characteristic of ‘Event-driven Simulator’?
a. Identification of timing violations
b. Storage of state values & time information
c. Time delay calculation
d. No event scheduling
ANSWER: No event scheduling
13) Which among the following is an output generated by synthesis process?
a. Attributes & Library
b. RTL VHDL description
c. Circuit constraints
d. Gate-level net list
ANSWER: Gate-level net list
14) Register transfer level description specifies all of the registers in a design & ______ logic between them.
a. Sequential
b. Combinational
c. Both a and b
d. None of the above
ANSWER: Combinational
15) In synthesis process, the load attribute specify/ies the existing amount of _________load on a particular output signal.
a. Inductive
b. Resistive
c. Capacitive
d. All of the above
16) Which attribute in synthesis process specify/ies the resistance by controlling the quantity of current it can source?
a. Load attribute
b. Drive attribute
c. Arrival time attribute
d. All of the above
ANSWER: Drive attribute
17) Which type of digital systems exhibit the necessity for the existence of at least one feedback path from output to input?
a. Combinational System
b. Sequential system
c. Both a and b
d. None of the above
ANSWER: Sequential system
18) The output of sequential circuit is regarded as a function of time sequence of __________.
A. Inputs
B. Outputs
C. Internal States
D. External States
a. A & D
b. A & C
c. B & D
d. B & C
ANSWER: A & C
19) The time required for an input data to settle _____ the triggering edge of clock is known as ‘Setup Time’.
a. Before
b. During
c. After
d. All of the above
ANSWER: Before
20) Hold time is defined as the time required for the data to ________ after the triggering edge of clock.
a. Increase
b. Decrease
c. Remain stable
d. All of the above
ANSWER: Remain stable
21) An Antifuse programming technology is predominantly associated with _____.
a. SPLDs
b. FPGAs
c. CPLDs
d. All of the above
ANSWER: FPGAs
22) In fusible link technologies, the undesired fuses are removed by the pulse application of _____voltage & current to device input.
a. Low
b. Moderate
c. High
d. All of the above
ANSWER: High
23) Which programming technology/ies is/are predominantly associated with SPLDs and CPLDs?
a. EPROM
b. EEPROM
c. FLASH
d. All of the above
ANSWER: All of the above
24) Before the commencement of design, the clocking strategy determine/s __________
a. Number of clock signals necessary for routing throughout the chip
b. Number of transistors used per storage requirement
c. Power dissipated by chip & the size of chip
d. All of the above
ANSWER: All of the above
25) Which method/s of physical clocking is/are a /the recursive structure where the memory elements are grouped together to make the use of nearby or same distribution points?
a. H tree
b. Balanced tree clock network
c. Both a and b
d. None of the above
ANSWER: H tree
26) Increase in the physical distance of H-tree _________the skew rate.
a. Increases
b. Stabilizes
c. Decreases
d. All of the above
ANSWER: Increases
27) Which type of MOSFET exhibits no current at zero gate voltage?
a. Depletion MOSFET
b. Enhancement MOSFET
c. Both a and b
d. None of the above
ANSWER: Enhancement MOSFET
28) In enhancement MOSFET, the magnitude of output current __________ due to an increase in the magnitude of gate potentials.
a. Increases
b. Remains constant
c. Decreases
d. None of the above
ANSWER: Increases
29) In DIBL, which among the following is/are regarded as the source/s of leakage?
a. Subthreshold conduction
b. Gate leakage
c. Junction leakage
d. All of the above
ANSWER: All of the above
30) Which among the following can be regarded as an/the application/s of MOS switch in an IC design?
a. Multiplexing & Modulation
b. Transmission gate in digital circuits
c. Simulation of a resistor
d. All of the above
ANSWER: All of the above
31) In MOS switch, clock feedthrough effect is also known as __________.
A. charge injection
B. charge feedthrough
C. charge carrier
D. charge ejaculation
a. A & B
b. B & C
c. C & D
d. B & D
ANSWER: A & B
32) Which among the following is/are regarded as an/the active resistor/s?
a. MOS diode
b. MOS transistor
c. MOS switch
d. All of the above
ANSWER: MOS diode
33) In testability, which terminology is used to represent or indicate the formal evidences of correctness?
a. Validation
b. Verification
c. Simulation
d. Integration
ANSWER: Verification
34) Which among the following is regarded as an electrical fault?
a. Excessive steady-state currents
b. Delay faults
c. Bridging faults
d. Logical stuck-at-0 or stuck-at-1
ANSWER: Excessive steady-state currents
35) Which among the following faults occur/s due to physical defects?
a. Process variations & abnormalities
b. Defects in silicon substrate
c. Photolithographic defects
d. All of the above
ANSWER: All of the above
36) In logic synthesis, ________ is an EDIF that gives the description of logic cells & their interconnections.
a. Netlist
b. Checklist
c. Shitlist
d. Dualist
ANSWER: Netlist
37) Which level of system implementation includes the specific function oriented registers, counters & multiplexers?
a. Module level
b. Logical level
c. Physical level
d. All of the above
ANSWER: Module level
38) Which among the following is/are taken into account for post-layout simulation?
a. Interconnect delays
b. Propagation delays
c. Logic cells
d. All of the above
ANSWER: All of the above
39) Which among the following operation/s is/are executed in physical design or layout synthesis stage?
a. Placement of logic functions in optimized circuit in target chip
b. Interconnection of components in the chip
c. Both a and b
d. None of the above
ANSWER: Both a and b
40) In VHDL, which class of scalar data type represents the values necessary for a specific operation?
a. Integer types
b. Real types
c. Physical types
d. Enumerated types
ANSWER: Enumerated types
41) Which among the following is pre-defined in the standard package as one-dimensional array type comprising each element of BIT type?
a. Bit type
b. Bit_vector type
c. Boolean type
d. All of the above
ANSWER: Bit_vector type
42) In composite data type of VHDL, the record type comprises the elements of _______data types.
a. Same
b. Different
c. Both a and b
d. None of the above
ANSWER: Different
43) Which among the following wait statement execution causes the enclosing process to suspend and then wait for an event to occur on the signals?
a. Wait until Clk = ‘1’
b. Wait on x,y,z
c. Wait on clock until answer > 80
d. Wait for 12 ns
ANSWER: Wait on x,y,z
44) After an initialization phase, the simulator enters the ______phase.
a. Compilation
b. Elaboration
c. Execution
d. None of the above
ANSWER: Execution
45) Which concept proves to be beneficial in acquiring concurrency and order independence?
a. Alpha delay
b. Beta delay
c. Gamma delay
d. Delta delay
ANSWER: Delta delay
46) An event is nothing but ______ target signal, which is to be updated.
a. Fixed
b. Change on
c. Both a and b
d. None of the above
ANSWER: Change on
47) Which functions are performed by static timing analysis in simulation?
a. Computation of delay for each timing path
b. Logic analysis in a static manner
c. Both a and b
d. None of the above
ANSWER: Both a and b
48) Which among the following is/are regarded as the function/s of translation step in synthesis process?
a. Conversion of RTL description to boolean unoptimized description
b. Conversion of an unoptimized to optimized boolean description
c. Conversion of unoptimized boolean description to PLA format
d. All of the above
ANSWER: Conversion of RTL description to boolean unoptimized description
49) In synthesis flow, which stage/s is/are responsible for converting an unoptimized boolean description to PLA format?
a. Translation
b. Optimization
c. Flattening
d. All of the above
ANSWER: Flattening
50) In synthesis flow, the flattening process generates a flat signal representation of _____levels.
A. AND
B. OR
C. NOT
D. EX-OR
a. A & B
b. C & D
c. A & C
d. B & D
ANSWER: A & B
51) If the level of fan-out is beyond a limit in synthesis, it results in an insertion of buffer by ultimate effect of _____ the speed.
a. Enhancing
b. Reducing
c. Stabilizing
d. None of the above
ANSWER: Reducing
52) Which among the following constraint/s is/are involved in a state-machine description?
a. State variable & clock
b. State transitions & output specifications
c. Reset condition
d. All of the above
ANSWER: All of the above
53) Which among the following is/are identical in Mealy & Moore machines?
a. Combinational output signal
b. Clocked Process
c. Both a and b
d. None of the above
ANSWER: Clocked Process
54) Which method/s is/are adopted for acquiring spike-free outputs?
a. Moore machine with clocked outputs
b. Mealy machine with clocked outputs
c. Output-state machine
d. All of the above
ANSWER: All of the above
55) In SM chart for UART transmitter, which state/s indicate/s the waiting of sequential machine for the rising edge of bit clock and the consequent clearing of low order bit of TSR in order to transmit logic ‘0’ for one bit time?
a. IDLE State
b. Sync State
c. Transmit_Data_State
d. All of the above
ANSWER: Sync State
56) The devices which are based on fusible link or antifuse are _________time/s programmable.
a. one
b. two
c. four
d. infinite
ANSWER: one
57) Which among the following is/are not suitable for in-system programming?
a. EPROM
b. EEPROM
c. Flash
d. All of the above
ANSWER: EPROM
58) Simple Programmable Logic Devices (SPLDs) are also regarded as _____________.
a. Programmable Array Logic (PAL)
b. Generic Array Logic (GAL)
c. Programmable Logic Array (PLA)
d. All of the above
ANSWER: All of the above
59) In signal integrity, which noise/s occur/s due to impedance mismatch, stubs, vias and other interconnection discontinuities?
a. Power/Ground Noise
b. Crosstalk Noise
c. Reflection Noise
d. All of the above
ANSWER: Reflection Noise
60) In floorplanning, placement and routing are __________ tools.
a. Front end
b. Back end
c. Both a and b
d. None of the above
ANSWER: Back end
61) In floorplanning, which phase/s play/s a crucial role in minimizing the ASIC area and the interconnection density?
a. Placement
b. Global Routing
c. Detailed Routing
d. All of the above
ANSWER: Placement
62) In CMOS inverter, the propagation delay of a gate is the/an _________ transition delay time for the signal during propagation from input to output especially when the signal changes its value.
a. Highest
b. Average
c. Lowest
d. None of the above
ANSWER: Average
63) In pull-up network, PMOS transistors of CMOS are connected in parallel with the provision of conducting path between output node & Vdd yielding _____ output.
a. 1
b. 0
c. Both a and b
d. None of the above
ANSWER: 1
64) For complex gate design in CMOS, OR function needs to be implemented by _______ connection/s of MOS.
a. Series
b. Parallel
c. Both series and parallel
d. None of the above
ANSWER: Parallel
65) In MOS devices, the current at any instant of time is ______of the voltage across their terminals.
a. constant & dependent
b. constant & independent
c. variable & dependent
d. variable & independent
ANSWER: constant & independent
66) On the basis of an active load, which type of inverting CMOS amplifier represents low gain with highly predictable small and large signal characteristics?
a. Active PMOS load inverter
b. Current source load inverter
c. Push-pull inverter
d. None of the above
ANSWER: Active PMOS load inverter
67) An ideal op-amp has ________
a. Infinite input resistance
b. Infinite differential voltage gain
c. Zero output resistance
d. All of the above
ANSWER: All of the above
68) Stuck open (off) fault occur/s due to _________
a. An incomplete contact (open) of source to drain node
b. Large separation of drain or source diffusion from the gate
c. Both a and b
d. None of the above
ANSWER: Both a and b
69) Which type/s of stuck at fault model exhibit/s the reduced complexity level of test generation?
a. Single
b. Multiple
c. Both a and b
d. None of the above
ANSWER: Multiple
70) Why is multiple stuck-at fault model preferred for DUT?
a. Because single stuck-at fault model is independent of design style & technology
b. Because single stuck-at tests cover major % of multiple stuck-at faults & unmodeled physical defects
c. Because complexity of test generation is reduced to greater extent in multiple stuck-at fault models
d. All of the above
ANSWER: All of the above
71) Which among the following EDA tool is available for design simulation?
a. OrCAD
b. ALDEC
c. Simucad
d. VIVElogic
ANSWER: VIVElogic
72) Which among the following functions are performed by MSI category of IC technology?
a. Gates, Op-amps
b. Microprocessor/A/D
c. Filters
d. Memory/DSP
ANSWER: Filters
73) The ‘next’ statements skip the remaining statement in the ________ iteration of loop and execution starts from first statement of next iteration of loop.
a. Previous
b. Next
c. Current (present)
d. None of the above
ANSWER: Current (present)
74) An Assert is ______ command.
a. Sequential
b. Concurrent
c. Both a and b
d. None of the above
ANSWER: Both a and b
75) Timing analysis is more efficient with synchronous systems whose maximum operating frequency is evaluated by the _________path delay between consecutive flip-flops.
a. shortest
b. average
c. longest
d. unpredictable
ANSWER: longest
76) What is/are the necessity/ies of Simulation Process in VHDL?
a. Requirement to test designs before implementation & usage
b. Reduction of development time
c. Decrease the time to market
d. All of the above
ANSWER: All of the above
77) Why is the use of mode buffer prohibited in the design process of synthesizer?
a. To avoid mixing of clock edges
b. To prevent the occurrence of glitches & metastability
c. Because critical path has preference in placement
d. Because Maximum ASIC vendors fail to support mode buffer in librari
ANSWER: Because Maximum ASIC vendors fail to support mode buffer in libraries
78) If a port is declared as buffer, then which problem is generated in hierarchical design due to mapping with port of buffer mode of other entities only?
a. Structural Modeling
b. Functional Modeling
c. Behavioral Modeling
d. Data Flow Modeling
ANSWER: Structural Modeling
79) Which UART component/s divide/s the system clock to provide the bit clock with the period equal to one bit time and Bclock x 8?
a. Baud Rate Generator
b. Transmitter Section
c. Receiver Section
d. All of the above
ANSWER: Baud Rate Generator
80) In Gray coding, when the state machine changes state, ______ bit/s in the state vector changes the value.
a. one
b. two
c. four
d. eight
ANSWER: one
81) Which type of CPLD packaging comprises pins on all four sides that wrap around the edges of chip?
a. Plastic-Leaded Chip Carrier (PLCC)
b. Quad Flat Pack (QFP)
c. Ceramic Pin Grid Array (PGA)
d. Ball Grid Array (BGA)
ANSWER: Plastic-Leaded Chip Carrier (PLCC)
82) An antifuse element initial provides ______ between two conductors in absence of the application of sufficient programming voltage.
a. Conduction
b. Insulation
c. Both a and b
d. None of the above
ANSWER: Insulation
83) In spartan-3 family architecture, which programmable functional element accepts two 18 bit binary numbers as inputs and computes the product?
a. Configurable Logic Blocks
b. Input Output Blocks
c. Block RAM
d. Multiplier Blocks
ANSWER: Multiplier Blocks
84) Which level of routing resources are supposed to be the dedicated lines allowing output of each tile to connect directly to every input of eight surrounding tiles?
a. Ultra-fast local resources
b. Efficient long-line resources
c. High speed, very long-line resources
d. High performance global networks
ANSWER: Ultra-fast local resources
85) Maze routing is also known as ________
a. Viterbi’s algorithm
b. Lee/Moore algorithm
c. Prim’s algorithm
d. Quine-McCluskey algorithm
ANSWER: Lee/Moore algorithm
86) Maze routing is used to determine the _______path for a single wire between a set of points, if any path exists.
a. Shortest
b. Average
c. Longest
d. None of the above
ANSWER: Shortest
87) In a chip, which type/s of pad design/s is/are adopted to solve the problem of pin count?
a. Input pad design
b. Output pad design
c. Three state pad design
d. All of the above
ANSWER: Three state pad design
88) The power consumption of static CMOS gates varies with the _____ of power supply voltage.
a. square
b. cube
c. fourth power
d. 1/8 th power
ANSWER: square
89) Which factor/s play/s a crucial role in determining the speed of CMOS logic gate?
a. Load capacitance
b. Supply voltage
c. Gain factor of MOS
d. All of the above
ANSWER: All of the above
90) In high noise margin (NMH), the difference in magnitude between the maximum HIGH output voltage of driving gate and the maximum HIGH voltage is recognized by the _________gate.
a. Driven
b. Receiving
c. Both a and b
d. None of the above
ANSWER: Receiving
91) In CMOS circuits, which type of power dissipation occurs due to switching of transient current and charging & discharging of load capacitance?
a. Static dissipation
b. Dynamic dissipation
c. Both a and b
d. None of the above
ANSWER: Dynamic dissipation
92) In accordance to the scaling technology, the total delay of the logic circuit depends on ______
a. The capacitor to be charged
b. The voltage through which capacitance must be charged
c. Available current
d. All of the above
ANSWER: All of the above
93) In two-stage op-amp, what is the purpose of compensation circuitry?
a. To provide high gain
b. To lower output resistance & maintain large signal swing
c. To establish proper operating point for each transistor in its quiescent state
d. To achieve stable closed-loop performance
ANSWER: To achieve stable closed-loop performance
94) According to the principle of current mirror, if gate-source potentials of two identical MOS transistors are equal, then the channel currents should be _______
a. Equal
b. Different
c. Both a and b
d. None of the above
ANSWER: Equal
95) PSSR can be defined as the product of the ratio of change in supply voltage to change in output voltage of op-amp caused by the change in power supply & _______ of op-amp.
a. Open-loop gain
b. Closed-loop gain
c. Both a and b
d. None of the above
ANSWER: Open-loop gain
96) Which among the following serves as an input stage to most of the op-amps due to its compatibility with IC technology?
a. Differential amplifier
b. Cascode amplifier
c. Operational transconductance amplifiers (OTAs)
d. Voltage operational amplifier
ANSWER: Differential amplifier
97) Which among the following is/are responsible for the occurrence of ‘Delay Faults’?
a. Variations in circuit delays & clock skews
b. Improper estimation of on-chip interconnect & routing delays
c. Aging effects & opens in metal lines connecting parallel transistors
d. All of the above
ANSWER: All of the above
98) Due to the limitations of the testers, the functional test is usually performed at speed _______the target speed.
a. Lower than
b. Equal to
c. Greater than
d. None of the above
ANSWER: Lower than
99) High observability indicates that ________number of cycles are required to measure the output node value.
a. More
b. Equal
c. Less
d. None of the above
ANSWER: Less
100) Basically, an observability of an internal circuit node is a degree to which one can observe that node at the _______ of an integrated circuit.
a. Inputs
b. Outputs
c. Both a and b
d. None of the above
ANSWER: Outputs
