VLSI Frequently asked interview Questions with answers

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• what is the difference between mealy and moore state-machines
• how to solve setup and hold violations in the design
• what is antenna violation & ways to prevent it
• we have multiple instances in RTL(Register Transfer Language), do you do anything special during synthesis stage
• what is tie-high and tie-low cells and where it is used
• what is the difference between latches and flip-flops based designs
• what is High-Vt and Low Vt cells
• what is LEF mean?
• what is DEF mean?
• steps involved in designing an optimal padring
• what is metastability and steps to prevent it
• what is local-skew, global skew and useful skew
• what are the various timing-paths which i should take care in my STA runs?
• what are the various components of leakage-power
• what are the various yield losses in the design
• what is meant by virtual clock definition and why do i need it
• what are the various variations which impacts timing of the design
• what are the various Design constraints used, while performing synthesis for a design
• specify few verilog constructs which are not supported by the synthesis tool
• what are the various capacitances with an MOSFET?
• Vds-Ids curve for an MOSFET, with increasing Vgs
• explain basic operation of an MOSFET
• what is channel length modulation
• what is body effect
• what is latchup in CMOS design and ways to prevent it?
• what are the various design changes you do to meet design power targets
• what is meant by library characterization
• what is meant by wireload model
• what are the measures to be taken to design for optimized area
• what all will you be thinking while performing floorplan
• what are the measures in the design taken for meeting signal integrity targets
• what are the measures taken in the Design achieving better yield
• what are the measures or precautions to be taken in the design when the chip has both analog and digital portions.
• what are the steps incorporated for Engineering Change order[ECO]
• what are the steps performed to achieve Lithography friendly Design
• what does synthesis mean?
• what are the pre-requistes to perform synthesis
• can you explain the synthesis flow
• what are the various ways to reduce clock insertion delay in the design
• what are the various functional verification methodologies
• what does formal verification mean
• how will you time the output path in STA
• how will you time the input path in STA
• what is false path mean in STA and in what scenarios falsepath can come
• what does multicycle path mean in STA and in what scenarios MCP can come
• what are source synchronous paths in STA
• Assume there is a specific requirement to preserve the logic during synthesis , how will you achieve it
• we have multiple instances in RTL, do you do anything special during synthesis stage
• what do you call an event and when do you call an assertion