40+ Verification Engineer Interview Questions and Answers

Ensure data integrity through proper communication protocols and error checking mechanisms.

• Use reliable communication protocols such as TCP/IP or UART

• Implement error checking mechanisms such as CRC or checksums

• Perform thorough testing and validation of the communication interface

• Ensure proper synchronization between HW and SW

• Implement retry mechanisms in case of communication failures

SoC architecture consists of multiple components like CPU, memory, peripherals, and interconnects. Transactions are done through buses.

• SoC architecture includes a CPU, memory, peripherals, and interconnects

• Interconnects are used to connect the components and enable communication

• Transactions are done through buses like AXI, AHB, or APB

• The components can be customized based on the application requirements

UVM can be used to create a testbench environment and integrate it with c based test cases using DPI-C.

• Create a UVM testbench environment using SystemVerilog

• Use DPI-C to integrate the c based test cases with the UVM environment

• Define a DPI import function in SystemVerilog to call the c functions

• Use UVM sequences to drive the test cases

• Use UVM scoreboard to verify the results

• Use UVM coverage to ensure complete coverage of the design

A 2 select line MUX can be created using NAND gates by cascading multiple gates in a specific configuration.

• Use two NAND gates to create an AND gate by connecting the inputs of the NAND gates together and taking the output from both gates.

• Use another NAND gate to create an OR gate by connecting the outputs of the two AND gates to the inputs of the OR gate.

• Connect the select lines to the inputs of the AND gates and the data lines to the inputs of the OR gate to complete the 2 ...read more

Bubble sort is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order.

• Compare adjacent elements and swap if necessary

• Repeat until no more swaps are needed

• Time complexity is O(n^2)

• Example: [5, 3, 8, 2, 1] -> [3, 5, 2, 1, 8] -> [3, 2, 1, 5, 8] -> [2, 1, 3, 5, 8] -> [1, 2, 3, 5, 8]

Firmware is a software program that controls hardware devices. Yes, I have done hardware testing. Our product is sustainable.

• Firmware is a type of software that is embedded in hardware devices to control their functionality.

• I have experience in testing hardware components such as circuit boards, processors, and memory modules.

• Our product is designed with sustainability in mind, using eco-friendly materials and energy-efficient components.

Design a finite state machine to count the number of people passing through a hallway with 2 detectors, allowing only one person at a time.

• Create states for each detector and the hallway

• Transition between states based on detector inputs

• Use counters to keep track of the number of people passing through

• Implement logic to prevent multiple people from passing simultaneously

Scoreboard is a verification component that tracks and compares expected and actual data.

• Scoreboard is used to monitor the progress of a design under test (DUT) and compare it with the expected behavior.

• It can be implemented using a register or a memory block.

• Scoreboard can be used to check the correctness of the DUT's output against the expected output.

• Expected data can be obtained from a reference model or a golden model.

• Scoreboard can be used in conjunction with other veri...read more

A Finite State Machine is a mathematical model used to represent and control the behavior of a system with a finite number of states.

• FSM consists of a set of states, transitions between states, and actions associated with transitions.

• Verilog code for a simple 2-state FSM: module fsm(input clk, input reset, output reg state); always @(posedge clk or posedge reset) begin if (reset) state <= 0; else state <= ~state; end endmodule

• FSMs are commonly used in digital design, control ...read more

Tasks are concurrent blocks of code that can run in parallel, while functions are sequential blocks of code that perform a specific task.

• Tasks can run concurrently, while functions run sequentially

• Tasks can be executed in parallel, while functions are executed one after the other

• Tasks are used for parallel processing, while functions are used for sequential processing

fork-join is a parallel programming model where a task is divided into subtasks that run concurrently and join at a synchronization point.

• fork-join is used in parallel programming to improve performance by dividing a task into smaller subtasks that can be executed concurrently

• In fork-join, the main task is divided into subtasks using the 'fork' operation, and these subtasks are executed independently

• The 'join' operation is used to synchronize the subtasks and wait for their c...read more

Code for Handshake in UVM

• Create a sequence item for handshake

• Use a sequence to drive the handshake

• Implement the handshake protocol in the driver and monitor

• Use analysis ports to check for successful handshake

Design muxes and write code for Fibonacci series

• Design a 2:1 mux using Verilog or VHDL

• Implement the Fibonacci series using a for loop or recursion

• Connect the output of the mux to select between the two Fibonacci numbers

• Test the design with different inputs and verify the output

Blocking operations wait until the operation completes, while non-blocking operations do not wait and allow other operations to continue.

• Blocking operations halt the execution until the operation is completed

• Non-blocking operations do not halt the execution and allow other operations to continue

• Blocking operations are synchronous, while non-blocking operations are asynchronous

• Example: In a blocking operation, a function call will wait for the function to return before proceed...read more

Print infinite series of a given pattern

• Use a loop to continuously print the pattern

• Consider using a circular buffer to store the pattern for efficient printing

• Ensure the pattern does not consume too much memory or cause overflow

Verify last level cache by running stress tests, analyzing cache hit/miss rates, and comparing performance metrics.

• Run stress tests to simulate high load scenarios and observe cache behavior

• Analyze cache hit/miss rates to ensure data is being efficiently stored and retrieved

• Compare performance metrics before and after cache verification to measure improvements

• Use tools like CacheGrind or Valgrind for detailed cache analysis

Understanding system requirements involves analyzing and interpreting the needs and constraints of a system.

• Reviewing the project documentation to identify key requirements

• Clarifying any ambiguities or inconsistencies in the requirements

• Communicating with stakeholders to ensure all requirements are captured accurately

• Translating high-level requirements into detailed technical specifications

• Creating test cases based on the requirements to verify system functionality

Microcontroller is a self-contained system with memory, peripherals and processor. Microprocessor is a CPU only.

• Microcontroller has on-chip memory and peripherals, while microprocessor requires external memory and peripherals

• Microcontroller is used in embedded systems, while microprocessor is used in general-purpose computing

• Examples of microcontrollers include Arduino, PIC, and AVR, while examples of microprocessors include Intel Pentium, AMD Ryzen, and ARM Cortex

In SystemVerilog, 'always' is used to describe a process that runs continuously, while 'initial' is used to describe a process that runs only once at the beginning of simulation.

• always blocks are used for describing processes that run continuously throughout the simulation

• initial blocks are used for describing processes that run only once at the beginning of simulation

• always blocks are sensitive to changes in their inputs and execute whenever there is a change

• initial blocks a...read more

SRAM and DRAM are types of computer memory with different characteristics. Blocking and non-blocking statements are used in hardware design.

• SRAM (Static Random Access Memory) is faster, more expensive, and consumes more power than DRAM (Dynamic Random Access Memory).

• SRAM stores data in a flip-flop circuit, while DRAM stores data in a capacitor.

• SRAM does not need to be refreshed, while DRAM requires periodic refreshing.

• Blocking statements in hardware design halt the execution ...read more

Polymorphism is the ability of a function or method to behave differently based on the object it is called with.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: Animal superclass with methods like eat() and sleep(), and subclasses like Dog and Cat that override these methods.

Identifying and fixing a race condition in a multi-threaded system

• Observed intermittent failures in test results

• Used debugging tools like gdb and log analysis to trace the issue

• Identified the root cause as a race condition between two threads

• Implemented a mutex lock to resolve the issue

• Verified the fix by running stress tests

Bit represents the smallest unit of data in a computer system, while logic refers to the operations and rules that govern the manipulation of data.

• A bit is a binary digit that can have a value of either 0 or 1.

• Logic refers to the principles and rules that determine how data is processed and manipulated.

• Bits are used to represent and store data, while logic is used to perform operations on that data.

• Bit-level operations involve manipulating individual bits, while logic-level o...read more

MCB stands for Miniature Circuit Breaker. It is an electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.

• MCB is a type of circuit breaker that automatically switches off electrical circuits during abnormal conditions.

• It is used to protect electrical appliances from damage caused by overloading or short circuiting.

• MCBs are available in different current ratings and tripping characteristics.

• They are commonly used in resident...read more

Delay inter and intra refer to delays within and between different components or systems.

• Delay inter refers to delays between different components or systems.

• Delay intra refers to delays within the same component or system.

• Example: Delay inter can occur when data is transferred between a CPU and memory.

• Example: Delay intra can occur within a CPU due to processing time.

Que in SystemVerilog (SV) is a built-in data type used for creating queues.

• Queues are dynamic arrays that can grow or shrink in size during simulation.

• Queues can store elements of any data type.

• Elements can be added to the end of the queue using the built-in methods like push_back().

• Elements can be removed from the front of the queue using the built-in methods like pop_front().

Testcases for software and hardware

• For software: unit testing, integration testing, system testing, acceptance testing

• For hardware: functional testing, performance testing, stress testing, environmental testing

• Testcases should cover all possible scenarios and edge cases

• Testcases should be repeatable and automated where possible

DRAM is volatile memory that stores data temporarily, while SRAM is faster and more expensive but retains data as long as power is supplied.

• DRAM stands for Dynamic Random Access Memory, while SRAM stands for Static Random Access Memory.

• DRAM requires refreshing to retain data, while SRAM does not.

• DRAM is slower and less expensive than SRAM.

• Examples of DRAM include DDR3 and DDR4, while examples of SRAM include L1, L2, and L3 cache in CPUs.

Universal Verification Methodology (UVM) is a standardized methodology for verifying digital designs.

• UVM is based on SystemVerilog and provides a standardized way to create testbenches for verifying digital designs.

• It helps in improving verification productivity, reusability, and scalability.

• UVM consists of a set of classes and macros that help in creating modular and reusable testbenches.

• It supports constrained random stimulus generation, functional coverage, and assertion-b...read more

MCB stands for Miniature Circuit Breaker, a device used to protect electrical circuits from overloads and short circuits.

• MCB is a type of circuit breaker that automatically switches off electrical circuits during abnormal conditions.

• It is commonly used in residential and commercial buildings to protect electrical appliances and wiring.

• MCBs are available in different current ratings and trip curves to suit different applications.

• They are more reliable and faster acting than tr...read more

A monitor for APB protocol is a verification component that checks for protocol compliance in APB transactions.

• Monitor should check for valid address, data, and control signals in APB transactions

• It should detect and report any protocol violations or errors

• Monitor should be able to track the state of the APB bus and ensure proper communication between master and slave devices

Procedural block is a construct in SystemVerilog used to group statements and declarations together.

• Procedural blocks include initial blocks, always blocks, and final blocks

• They are used to define behavior in hardware description languages like SystemVerilog

• Procedural blocks can contain sequential statements, parallel blocks, and control flow statements

DO-178B is an older standard for software development in avionics, while DO-178C is the updated version with more modern practices.

• DO-178B was released in 1992, while DO-178C was released in 2011.

• DO-178C includes more detailed guidance on software verification and validation.

• DO-178C allows for more flexibility in the use of modern software development practices compared to DO-178B.

• DO-178C emphasizes the use of formal methods and tools for software verification.

• DO-178C introdu...read more

To start a sequence, you need to define the sequence type, specify the starting value, and set the increment or decrement value.

• Define the sequence type: arithmetic, geometric, or custom

• Specify the starting value of the sequence

• Set the increment or decrement value for arithmetic or geometric sequences

• For custom sequences, define the sequence pattern or rule

• Examples: Arithmetic sequence starting from 1 with an increment of 2: 1, 3, 5, 7, ...

• Geometric sequence starting from 2 w...read more

Constraints in verification engineering are conditions or limitations imposed on the design or testbench to ensure certain properties are met.

• Constraints are used to restrict the possible values of variables or signals in a design or testbench.

• They help in verifying specific behaviors or scenarios within the design.

• Examples include setting timing constraints for signal propagation or limiting the range of input values for a module.

A mailbox is a data structure used for communication between different processes or threads in a computer system.

• Mailboxes are typically used in multi-threaded or multi-processor systems to pass messages between different entities.

• They provide a way for processes to communicate without directly accessing each other's memory.

• Mailboxes can be implemented using queues, shared memory, or other mechanisms depending on the system requirements.

Object-oriented programming concepts such as classes, objects, inheritance, encapsulation, and polymorphism.

• Classes: Blueprint for creating objects with attributes and methods.

• Objects: Instances of classes that contain data and behavior.

• Inheritance: Ability for a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability for objects of different classes to respond to th...read more

Mux combines multiple inputs into a single output, while demux separates a single input into multiple outputs.

• Mux stands for multiplexer and has multiple inputs and one output.

• Demux stands for demultiplexer and has one input and multiple outputs.

• Mux is used to select one of the input lines and forward it to the output line.

• Demux is used to distribute the input signal to one of the many output lines based on the control signal.

• Example: A 4-to-1 mux takes 4 input lines and sele...read more

Yes, PCIE stands for Peripheral Component Interconnect Express, a high-speed serial computer expansion bus standard.

• PCIE is a high-speed serial computer expansion bus standard used for connecting hardware devices to a computer's motherboard.

• It is commonly used for graphics cards, network cards, and storage devices.

• PCIE offers faster data transfer rates compared to older bus standards like PCI and AGP.

• PCIE versions include PCIE 1.0, 2.0, 3.0, and the latest PCIE 4.0 and 5.0.

• PC...read more

Verilog is a hardware description language used for designing digital circuits.

• Verilog is used to describe the behavior of electronic systems.

• It is commonly used in the design and verification of digital circuits.

• Verilog code consists of modules, which can be instantiated and interconnected to create complex systems.

• Simulation tools like ModelSim can be used to test Verilog code before implementation on hardware.

FIFO full condition occurs when the FIFO buffer is completely filled with data.

• Occurs when the number of items in the FIFO buffer reaches its maximum capacity

• Further writes to the FIFO buffer are blocked until some data is read out

• Can lead to data loss if not managed properly

UVM (Universal Verification Methodology) basic principle is to provide a standardized methodology for verifying digital designs.

• UVM is based on SystemVerilog and provides a framework for creating reusable verification environments

• It promotes the use of object-oriented programming techniques for creating modular and scalable testbenches

• UVM encourages the use of constrained-random stimulus generation and coverage-driven verification

• It includes components such as sequences, driv...read more