70+ Design & Verification Engineer Interview Questions and Answers

Questions on XOR gate, comparing 4 bit numbers using gates and rotating bits.

• XOR gate is a logical gate that outputs true only when the inputs differ.

• To compare two 4 bit numbers using gates, we can use a combination of XOR, AND and OR gates.

• To rotate bits, we can use shift registers or rotate registers.

• If we rotate 5 times, the bits will rotate by 5 positions and the last 5 bits will become the first 5 bits.

Setup time and hold time are timing constraints in digital circuits to ensure proper operation of flip-flops.

• Setup time is the minimum amount of time data must be stable before the clock edge for it to be reliably sampled.

• Hold time is the minimum amount of time data must be stable after the clock edge for it to be reliably sampled.

• Setup time violations can lead to metastability issues in flip-flops.

• Hold time violations can lead to data corruption in flip-flops.

• Setup time is i...read more

The $cast operator is used to convert one data type to another. Types of arrays include fixed-size, dynamic, and multi-dimensional.

• The $cast operator is commonly used in C++ to convert between data types.

• Fixed-size arrays have a predetermined number of elements, while dynamic arrays can be resized during runtime.

• Multi-dimensional arrays can have more than one index, such as a 2D array with rows and columns.

• Arrays can also be declared as pointers, allowing for dynamic memory a...read more

A mux (multiplexer) is a digital circuit that selects one of multiple input signals and forwards it to a single output.

• Mux is used to select one of multiple input signals based on the select lines.

• The number of select lines determines the number of input signals that can be selected.

• Common examples of mux include 2:1 mux, 4:1 mux, and 8:1 mux.

Regular expressions are patterns for string matching, while logic involves reasoning and truth values in statements.

• Regular expressions (regex) are used for searching and manipulating strings based on defined patterns. Example: '^[a-z]+$' matches lowercase letters.

• Logic involves formal systems of reasoning, often using propositional or predicate logic. Example: 'A AND B' is true only if both A and B are true.

• Regex is primarily concerned with text processing, while logic is us...read more

Interface signals can be called at sequence level in UVM using the uvm_config_db class.

• Use uvm_config_db#(type)::set/get methods to access interface signals at sequence level

• Register the interface signal in the configuration database before accessing it in the sequence

• Example: uvm_config_db#(virtual interface)::set(null, "my_sequence", "my_interface", my_interface)

VLSI design flow includes steps from specification to fabrication, with RTL and netlist differing in abstraction levels.

• VLSI design flow includes specification, RTL design, synthesis, place & route, and verification.

• RTL (Register Transfer Level) describes the design in terms of data flow and timing, while netlist represents the actual circuit connections.

• Synthesis converts RTL code into a netlist, optimizing for area, speed, and power.

• Example of RTL: A Verilog module defining...read more

Arm advanced microcontroller based bus architecture is a high-performance, low-power bus architecture designed for Arm microcontrollers.

• Designed for Arm microcontrollers to provide high performance and low power consumption

• Supports advanced features like multiple bus masters, bus arbitration, and bus error handling

• Commonly used in embedded systems and IoT devices

• Examples include Arm Cortex-M series microcontrollers with AMBA bus architecture

Universal Asynchronous Receiver Transmitter is a hardware device used for serial communication.

• UART is commonly used for asynchronous communication between devices

• It consists of a transmitter and a receiver

• Data is sent in a serial format with start and stop bits

• Common baud rates include 9600, 19200, 38400, etc.

Universal gates are gates which can be used to implement any other gate. NAND and NOR gates are examples of universal gates.

• Universal gates can be used to implement any other gate in digital circuits.

• NAND gate and NOR gate are examples of universal gates.

• NAND gate can be constructed using NOR gates by applying De Morgan's theorem.

The driver communicates with the sequencer through signals and interfaces.

• Driver sends commands and data to the sequencer through communication interfaces like SPI, I2C, or UART.

• Sequencer receives the commands and data, processes them, and generates appropriate responses.

• Communication between driver and sequencer can also involve handshaking signals to ensure data integrity and synchronization.

AHB and APB are AMBA protocols; a bridge connects them for compatibility and efficient communication in SoC designs.

• AHB (Advanced High-performance Bus): A high-speed bus protocol designed for high-bandwidth applications, supporting burst transfers.

• APB (Advanced Peripheral Bus): A simpler, low-power bus protocol used for connecting low-bandwidth peripherals, optimizing power consumption.

• Bridge Functionality: A bridge is necessary to connect AHB and APB, allowing high-speed pro...read more

FSM for processing two input sequences

• Define states for each digit in the input sequence

• Transition between states based on current input and previous state

• Handle invalid inputs or transitions with error state

Design test cases and assertions for a simple FSM similar to a multiplexer.

• Identify states: Define all possible states of the FSM.

• Define inputs: List all inputs that can affect state transitions.

• Create state transition table: Map inputs to state transitions.

• Write test cases: Example - Test input combinations leading to each state.

• Assertions: Example - Assert that the FSM reaches the expected state after a given input.

Copy creates a new reference to the same object while clone creates a new object with the same values.

• Copy points to the same object while clone creates a new object

• Copy is shallow while clone is deep

• Copy is faster than clone

• Copy is used for mutable objects while clone is used for immutable objects

Blocking assignments wait for the assigned value to be calculated before moving on to the next statement, while non-blocking assignments allow multiple assignments to occur simultaneously.

• Blocking assignments use the = operator, while non-blocking assignments use the <= operator

• Blocking assignments are executed sequentially in the order they appear in the code, while non-blocking assignments are executed concurrently

• Blocking assignments are used for combinational logic, while...read more

Stacks and queues are data structures that manage collections of elements, differing in their order of access.

• Stack: Follows Last In First Out (LIFO) principle; the last element added is the first to be removed. Example: Undo functionality in text editors.

• Queue: Follows First In First Out (FIFO) principle; the first element added is the first to be removed. Example: Print job scheduling.

• Operations: Stacks use push (add) and pop (remove) operations, while queues use enqueue (a...read more

Assertions ensure design meets requirements, enhancing verification through formal checks.

• Functional Assertions: Check if outputs match expected results, e.g., 'if input A=1, output B should be 0'.

• Temporal Assertions: Validate sequences over time, e.g., 'event X must occur before event Y'.

• Protocol Assertions: Ensure compliance with communication protocols, e.g., 'data must be valid before transmission'.

• Safety Assertions: Verify system safety conditions, e.g., 'system must not...read more

A 4x4 matrix with diagonal elements as multiples of 5.

• Diagonal elements: [5, 10, 15, 20]

• Non-diagonal elements can be any value

• Example matrix: [[5, 2, 3, 4], [1, 10, 6, 7], [8, 9, 15, 11], [12, 13, 14, 20]]

Verilog tb is used for Verilog testbenches while SystemVerilog tb is used for SystemVerilog testbenches.

• Verilog tb uses Verilog language for testbenches while SystemVerilog tb uses SystemVerilog language.

• SystemVerilog tb provides more advanced features like classes, randomization, and coverage.

• SystemVerilog tb allows for easier integration of verification components and reuse of code.

• Verilog tb may require more manual coding for tasks that are automated in SystemVerilog tb.

SystemVerilog arrays are data structures that store multiple elements of the same data type. Tasks and functions are reusable blocks of code.

• SystemVerilog arrays can be declared using the 'array' keyword, with different types like dynamic arrays, associative arrays, and queues.

• Tasks are reusable blocks of code that can contain a sequence of statements and can be called multiple times within a module.

• Functions are similar to tasks but return a value and can be used to perform ...read more

m_sequencer and p_sequencer are components used in design and verification for sequencing operations.

• m_sequencer and p_sequencer are commonly used in digital design for controlling the sequence of operations.

• m_sequencer typically refers to a master sequencer, while p_sequencer refers to a peripheral sequencer.

• These components are often used in verification environments to ensure proper sequencing of events.

• For example, m_sequencer may control the overall flow of a testbench, ...read more

Phases are needed to break down complex tasks into manageable parts, ensuring proper planning, execution, and tracking.

• Phases help in proper planning and organization of tasks

• Phases allow for better tracking of progress and milestones

• Phases help in managing dependencies and resources effectively

• Phases enable better communication and collaboration among team members

Factory override in UVM allows users to replace default factory methods with custom implementations.

• Factory override is used to customize the behavior of UVM components without modifying the original source code.

• It allows users to replace default factory methods with custom implementations to meet specific requirements.

• Factory override can be useful for debugging, testing, or adding new features to existing UVM components.

• Example: Overriding the default create method in a UVM...read more

UART protocol can be used to transmit and receive data between two devices.

• UART can be used to communicate between a microcontroller and a computer

• UART can be used to send and receive data between two microcontrollers

• UART can be used to interface with sensors and actuators

• UART can be used to implement a simple command/response protocol

• UART can be used to implement a data logging system

MOSFET and BJT are both types of transistors used in electronic circuits, but they differ in terms of construction, operation, and characteristics.

• MOSFET stands for Metal-Oxide-Semiconductor Field-Effect Transistor, while BJT stands for Bipolar Junction Transistor.

• MOSFET is a voltage-controlled device, while BJT is a current-controlled device.

• MOSFET has a high input impedance and low output impedance, while BJT has a low input impedance and high output impedance.

• MOSFET has a ...read more

UART can be used to receive signals from a microcontroller.

• Connect the UART pins of the microcontroller to the UART pins of the receiving device.

• Configure the UART settings such as baud rate, parity, and stop bits.

• Use a UART library or write code to read the incoming data from the UART buffer.

• Process the received data as required by the application.