10+ Fpga Design Engineer Interview Questions and Answers

FPGA stands for Field-Programmable Gate Array, a type of integrated circuit that can be reconfigured after manufacturing.

• FPGA is a type of hardware that can be programmed to perform specific tasks.

• It consists of a matrix of configurable logic blocks connected via programmable interconnects.

• FPGAs are commonly used in applications such as signal processing, data processing, and control systems.

• Examples of FPGA manufacturers include Xilinx, Intel (formerly Altera), and Lattice S...read more

Blocking and non-blocking are two types of assignments in Verilog that differ in their execution order and timing.

• Blocking assignments execute in a sequential order and the next statement waits for the current statement to complete before executing.

• Non-blocking assignments execute concurrently and the next statement does not wait for the current statement to complete before executing.

• Blocking assignments are used for combinational logic while non-blocking assignments are used...read more

Code for read and write file

• Use fopen() function to open a file

• Use fprintf() function to write to a file

• Use fscanf() function to read from a file

• Close the file using fclose() function

CDC stands for Clock Domain Crossing. It refers to transferring data between different clock domains in an FPGA design.

• CDC occurs when signals cross between different clock domains in an FPGA design

• CDC can lead to metastability issues if not handled properly

• Common CDC techniques include synchronizers, handshake protocols, and FIFO buffers

• Examples of CDC techniques include 2-flop synchronizers, Gray coding, and CDC FIFOs

Task and function are subprograms in Verilog used for code modularity and reusability.

• Functions return a value while tasks do not.

• Functions can be called from expressions while tasks cannot.

• Tasks can have delays and event controls while functions cannot.

• Functions can have multiple return statements while tasks cannot.

• Functions can have input and output arguments while tasks can only have input arguments.

RAM and FIFO are essential components in FPGA design. Here's how to write code for them.

• For RAM, define the memory size and data width, then instantiate the memory module and write/read data using the address bus and data bus.

• For FIFO, define the depth and data width, then instantiate the FIFO module and write/read data using the write and read pointers.

• Use synchronous or asynchronous reset signals to initialize the RAM and FIFO modules.

• Consider the clock frequency and timing...read more

HOLD time is the minimum time data must be stable before the clock edge, while SETTLING time is the time required for the output to stabilize after a change in input.

• HOLD time ensures that data is stable before the clock edge to prevent setup time violations.

• SETTLING time is the time taken for the output to settle to its final value after a change in input.

• Both HOLD and SETTLING times are critical for ensuring proper operation of digital circuits.

• For example, in a flip-flop, ...read more

Use a frequency counter or oscilloscope to measure the period of a known signal and calculate the frequency.

• Measure the period of a known signal using a frequency counter or oscilloscope.

• Calculate the frequency using the formula: Frequency = 1 / Period.

• For example, if the period of the signal is 10 ms, the frequency would be 1 / 0.01 = 100 Hz.

A HalfAdder program in VHDL is used to perform addition of two binary digits without considering the carry.

• Declare two input signals A and B of type std_logic.

• Declare two output signals Sum and Cout of type std_logic.

• Implement the XOR gate for Sum and AND gate for Cout.

• Example: A <= '1'; B <= '0'; Sum <= A XOR B; Cout <= A AND B;

Reset is a signal used to initialize the system or a specific module.

• Reset is used to bring the system or module to a known state.

• It is an asynchronous signal that overrides all other signals.

• There are different types of resets such as power-on reset, soft reset, hard reset, etc.

• Reset can be active high or active low depending on the design.

• Reset can be generated internally or externally.

• Reset can be used to clear registers, counters, and other state elements.

Improving logic used in FPGA design involves optimizing resource utilization, reducing power consumption, and enhancing performance.

• Utilize efficient coding techniques to minimize logic complexity

• Implement pipelining to improve performance

• Use advanced synthesis and optimization tools to reduce resource usage

• Optimize clocking strategies to minimize power consumption

• Consider parallel processing to increase throughput

Design a counter using flip-flops to count up or down based on the input signal.

• Use D flip-flops to store the count value

• Connect the output of one flip-flop to the input of the next flip-flop to create a ripple effect

• Use additional logic gates to control the direction of counting (up or down)

• Implement a reset signal to initialize the counter to a specific value