100+ ASIC Design Multiple Choice Questions with Answers

The Application-Specific Integrated Circuit (ASIC) design flow is a complex, multi-step process that transforms a functional specification into a manufacturable silicon chip. It spans front-end design, including RTL coding and functional verification, synthesis, static timing analysis, floorplanning, placement and routing, physical verification, DFT (Design for Testability), and signoff for fabrication.

Mastering ASIC design requires not only understanding each step but also the interactions between them, such as how timing closure, power integrity, and signal integrity affect the final chip performance. Engineers need a solid grasp of standard cell libraries, clock tree synthesis, parasitic extraction, low-power techniques, and ECO methodology, among others.

This collection of 100 multiple-choice questions (MCQs) is carefully crafted to test your understanding of the ASIC design flow. It covers:

Front-End Design Concepts: RTL coding, functional verification, synthesis, STA
Physical Design: Floorplanning, placement, CTS, routing, parasitic aware optimization
Low-Power Techniques: Multi-Vt cells, UPF, clock gating, power grid design
DFT & Verification: Scan chains, MBIST, post-layout verification, ECO
Signoff & Manufacturability: IR drop, metal density, LVS, DRC, GDSII

Each question includes hints and detailed explanations to help you think critically, understand why the answer is correct, and apply concepts in real-world ASIC projects.

Whether you are an electronics student, aspiring ASIC engineer, or practicing professional, these MCQs will help you test your knowledge, prepare for exams, and reinforce best practices in modern ASIC design.

1). Which step of ASIC Design converts high-level RTL into gate-level netlist?

Floorplanning

Synthesis

DRC Checking

LVS Verification

2). In ASIC flow, technology libraries are primarily used during ___?

Packaging

Synthesis and P&R

LVS only

ERC only

3). What is the main purpose of RTL Simulation?

Check final layout timing

Verify logical behavior before synthesis

Analyze parasitics

Reduce chip area

4). Which file is typically used for gate-level timing simulation?

.vcd

sdf

.spef

.gds

5). Purpose of Design for Testability (DFT) insertion is to?

Increase power efficiency

Improve test coverage in manufacturing

Reduce routing congestion

Shrink die size

6). Floorplanning mainly deals with?

Functional behavior

Placement of blocks & IO ring planning

Logic optimization

Netlist creation

7). CTS (Clock Tree Synthesis) objective is to minimize?

Setup margin

Skew & latency

Routing time

Die thickness

8). Which file represents physical mask layout of ASIC?

GDSII

Liberty

SDC

UPF

9). Timing violation primarily occurs when?

Hold time < required

Path delay > clock period

More vias used

Via stacking limit exceeded

10). Which optimization resolves hold violations?

Adding buffers

Reducing load

Increasing frequency

Shrinking cell size

11). IR Drop issues directly affect?

Leakage power

Voltage delivered to cells

Chip temperature

Signal slew

12). LVS ensures?

Layout follows design rules

Layout matches schematic/netlist connectivity

Power meshes are dense

No timing violations

13). DRC checks violations related to?

Logical mismatches

Timing closure

Physical rule constraints

Scan chain breaks

14). ECO stands for?

Engineering Change Order

Electrical Clock Optimization

Enhanced Chip Operation

Environment Chip Object

15). Which stage adds scan flops?

Placement

DFT Insertion

LVS

GDS export

16). Parasitic extraction generates?

SDF

SPEF

Liberty

Verilog

17). Which tool type performs STA?

Layout editor

Timing analyzer

HDL editor

Spice simulator

18). Power gating is used to reduce?

ynamic power only

Leakage power

Area overhead

Clock skew

19). Which approach confirms chip after tape-out?

RTL simulation

Post-silicon validation

DRC

Floorplanning

20). SDC file contains?

Cell dimensions

Timing constraints

Routing resources

Mask patterns

21). Scan enable (SE) signal is used during?

Normal mode only

Test mode only

Normal + Test mode

DFT removal

22). Metal density rules are checked during?

RTL coding

DRC

Synthesis

Scan insertion

23). Double patterning is required for?

Lower frequencies

Advanced process nodes (<20nm)

High-power chips only

FPGA design only

24). Antenna effect is caused by?

Clock domain crossing

Charge accumulation during fabrication

IR drop

High transition time

25). Why is CTS done after placement?

Clocks don’t need routing

Cell locations are required to balance paths

It must be before synthesis

Avoid power analysis first

ASIC Design MCQs for Interviews

26). In a synchronous ASIC design, maximum clock frequency is limited by?

Hold path delay

Setup path delay

Fan-out only

IO pad delay

27). Multi-cycle paths are declared in SDC to?

Reduce routing resources

Relax timing requirement for slow logic

Accelerate hold fixing

Reduce voltage drop

28. False paths are created to?

Fix IR drop

Reduce area

Exclude paths from STA timing analysis

Reduce leakage

29). Clock Domain Crossing (CDC) issues mainly cause?

IR drop

Metastability

ECO errors

Scan shift failure

30). Retiming in synthesis is used to?

Break combinational logic by inserting flip-flops

Merge power rings

Increase scan depth

Resize cells only

31). Which reduces dynamic power in ASIC design?

Power gating

Clock gating

Antenna diode

ECO buffering

32). The output of logic synthesis is mainly a?

RTL file

Gate-level netlist

GDSII

SPEF

33). Standard cells are arranged in?

Hexagonal grid

Row-based structure

Random blocks

Hierarchical clusters only

34). The purpose of Placement Optimization is to?

Reduce leakage power only

Improve timing & congestion

Export GDSII

Perform DRC

35). In STA, a path failing hold but passing setup means?

Data too slow

Data too fast

Clock instability

Wrong SDC defined

36). Which is used for low-power intent specification?

.vcd

.upf

.sdf

.lef

37). Metal short issues are detected in?

STA

LVS

DRC

38). Parasitics affect timing by?

Increasing leakage

Increasing RC delays

Reducing drive strength

Reducing test coverage

39). Tape-out is the stage where?

RTL is coded

Final verified layout is sent for fabrication

Scan is inserted

Floorplanning begins

40). Which analysis ensures no EM overstress in metal lines?

IR drop

Electromigration analysis

CPI

Static timing analysis

41). Fill cells are inserted to?

Reduce hold violation

Maintain well continuity & metal density

Improve scan chain

Fix antenna

42). Which is NOT part of physical verification?

LVS

DRC

STA

ERC

43. Spare cells in ASIC used for?

Add ECO logic later

Reduce leakage

Increase performance

Reduce routing

44). IR drop is more critical in?

Low frequency designs

High switching activity blocks

ROM memory

Pads only

45). Which fix helps setup violation?

Add delay buffers

Use higher drive strength / upsizing

Reduce cell size

Remove clock gating

46). Timing closure happens after?

Floorplanning

Placement, CTS and Routing

RTL simulation

Library creation

47). Memory BIST is inserted to test?

Scan chains

SRAM/ROM blocks

IO pads

GDS patterns

48). Boundary scan (JTAG) follows standard?

IEEE 802.3

IEEE 1149.1

IEEE 1800

IEEE 1588

49). Soft Macro vs Hard Macro difference?

Soft has fixed layout

Soft delivered in RTL/Netlist form

Hard macro is technology-independent

Hard macro cannot be placed

50). Which step produces routed wires and final layout geometry?

Placement

Routing

Synthesis

DFT insertion

ASIC Design MCQs for Quiz

51). Which timing corner is used to check setup violations?

Fast-Fast (FF)

Slow-Slow (SS)

Typical (TT)

Only TT & FF

52). Hold timing is analyzed in which corner?

Any corner

53). Liberty (.lib) files contain?

Layout view

Timing, power, cell behavior

GDS polygons

Test patterns

54). Which one is not a physical design objective?

Timing closure

Routing congestion minimization

Functional verification

IR/EM safety

55). Which improves routing congestion?

Add fillers

Spread placement density

Increase switching activity

Decrease power straps

56). Redundant via insertion mainly improves?

Power

Reliability & yield

Area

Test coverage

57). Dummy metal fill is required for?

IR drop

Antenna fixing

Metal density balancing

CTS balancing

58). Which step extracts RC parasitics?

LVS

DRC

Parasitic extraction (PEX)

Synthesis

59). Clock mesh offers?

Higher skew

Lower skew but more power

Lower power only

No CTS needed

60). Antenna rule fixes require?

Well taps

Jumping layers or antenna diode

IO ring resizing

Clock tree resizing

61). Placement legalization ensures?

LVS correctness

No cells overlap

IO timing closure

DRC pass only

62). Which reduces leakage power most effectively?

Multi-Vt usage

Clock gating only

Retiming

Macro placement

63). In scan chain, shift operations occur at?

Functional frequency

Very low frequency

Highest achievable frequency

Random clock settings

64). STA signoff ensures?

No design rule violations

No timing violations across all corners

Perfect functionality

No IR drop

65). PVT refers to?

Power, Vdd, Temperature

Process, Voltage, Temperature

Power, Voltage, Timing

Process, Variation, Timing

66). ECO targeting setup failure usually involves?

Downsize cells

Replace cells with higher drive strength

Insert buffers

Increase wire resistance

67). Gate-level simulation is mainly required to validate?

RTL logic

Power grid

Timing annotated glitches & X-propagation

Package parasitics

68). Which contributes most to dynamic power consumption?

Leakage

Clock network

SRAM

Fill cells

69). Timing budgeting occurs during?

CDR

Floorplanning & Synthesis

LVS

GDS export

70). Metal layer usage increases with?

Smaller design

Higher routing congestion

Lower cell density

Low fan-out paths

71). Power straps are added to?

Improve timing

Reduce IR drop

Reduce routing layers

Lower area

72). Signoff DRC ensures?

No timing issues

Layout follow foundry min/max rules

IO ring stability

GLS accuracy

73). SRAM blocks in physical design are treated as?

Soft cells

Hard macros

Spare cells

IO fillers

74). The final GDSII transfer to foundry is called?

Packaging

Tape-out

LVS execution

RTL handoff

75). If routing congestion occurs around macros, best fix is?

Increase macro halos/keep-out

Reduce filler cells

Add tap cells

Hide macro pins

ASIC Design MCQs for Exams

76). What is the primary purpose of Metal Fill in ASIC layouts?

Improve routing congestion

Meet metal density rules for CMP

Reduce setup timing violations

Insert DFT logic

77). What is the role of “Keep-Out Zones” in floorplanning?

Reduce IR drop

Prevent placing cells near macros or IOs

Optimize clock tree

Adjust power domain

78). Multi-Vt cell usage helps in?

Improving timing and reducing leakage power

Increasing parasitic capacitance

Simplifying DFT

Reducing metal density

79). Which stage detects and fixes floating nodes in the layout?

Floorplanning

LVS / ERC check

Placement

CTS

80). What is the main reason for inserting decoupling capacitors?

Reduce routing congestion

Stabilize voltage rails and reduce noise

Speed up combinational logic

Reduce cell height

81). What is the purpose of “Macro Placement” in ASIC design?

Place standard cells

Place pre-designed blocks like memories and IPs optimally

Perform timing closure

Check DRC

82). What is the primary role of “Static Timing Analysis” (STA)?

Simulate functional logic

Verify all paths meet setup and hold timing without dynamic simulation

Check metal density

Generate scan chains

83). What does parasitic-aware synthesis achieve?

Ignoring wire delays

Optimizing logic considering interconnect RC delays

Faster DRC checks

Reduces chip area only

84). In ASIC design, a “Hold Violation” occurs when?

Data arrives too late

Data arrives too early

Clock is too slow

Clock tree is balanced

85). Which type of buffer insertion is done for clock nets to balance load?

Data buffer

Clock buffer

Retiming buffer

Scan buffer

86). Which file contains information for power-aware synthesis?

.lib

sdc

.upf

.gds

87). What is the main role of “Design for Manufacturability (DFM)” checks?

Improve timing

Ensure chip can be reliably fabricated

Reduce scan chain length

Optimize RTL code

88). Why are “Buffer Insertion” or “Wire Sizing” applied to data paths?

Reduce DRC violations

Optimize timing for setup and hold

Reduce chip area

Simplify scan chain

89). What is the primary goal of “Clock Tree Synthesis (CTS)”?

Minimize wire length only

Distribute clock with minimal skew and delay

Place all macros

Insert scan chains

90). Which is a common method to reduce IR drop in high-current nets?

Increase wire width and use power straps

Reduce cell sizes

Add more buffers

Increase clock skew

91). What is “Metal Density Rule” in ASIC layout?

Maximum number of metals per layer

Ensures uniform distribution of metals for CMP planarization

Number of vias allowed

Determines wire length

92). What is the purpose of “Spare Cells”?

Reduce leakage

Reserve logic for post-layout ECO changes

Reduce area

Improve routing

93). Which ASIC design stage requires PEX (Parasitic Extraction)?

RTL coding

Post-placement and routing

Floorplanning

DFT insertion

94). What is the function of “Scan Chain Insertion”?

Optimize clock skew

Facilitate testing of sequential elements after fabrication

Reduce IR drop

Improve timing closure

95). When is “ECO” (Engineering Change Order) typically applied?

Before RTL coding

After placement and timing analysis to fix issues

During library characterization

During tape-out only

96). Why is “Retiming” used in ASIC design?

To change placement of macros

To move sequential elements and balance critical paths

To fix IR drop

To insert scan chains

97). “Post-layout simulation” is performed using?

RTL only

Gate-level netlist with parasitic delays

SDC constraints

Hard macros only

98). What is the main goal of “Hold Fixing” in ASIC?

Ensure signals arrive early

Delay signals that arrive too fast

Upsize cells

Optimize placement

99). Which file contains final layout geometry for manufacturing?

SDC

GDSII

Liberty (.lib)

SPEF

100). Why is “Power Grid Insertion” critical in ASIC design?

To reduce scan chain length

To deliver stable voltage across all cells and reduce IR drop

To optimize timing paths

To facilitate LVS