FPGA logic implementation style Most modern FPGA logic modules implement arbitrary combinational functions primarily using which architectural approach?

Introduction / Context:
Modern FPGAs implement arbitrary logic by storing truth tables in small memories inside each logic element. Recognizing this approach helps you reason about how synthesis maps equations and why certain structures, like carry chains, speed up arithmetic.

Given Data / Assumptions:

• Common FPGA families (e.g., Intel/Altera, AMD/Xilinx) use LUT-based logic elements.
• A LUT is a small memory that outputs a value based on its input address, thereby realizing any function up to the LUT’s input width.
• Dedicated fast paths (e.g., carry chains) complement LUTs for arithmetic speed.

Concept / Approach:
A LUT (look-up table) with n inputs stores 2^n entries representing the function’s truth table. By programming these entries, the FPGA can implement any logic function of up to n variables per LUT, and then compose larger functions with multiple LUTs and routing.

Step-by-Step Solution:

Verification / Alternative check:
Review any vendor architecture guide; LUT sizes (e.g., 4-input, 6-input) are an advertised parameter and central to device capabilities.

Why Other Options Are Wrong:
“AND array,” “OR array,” and “AND and OR array” describe classic PAL/CPLD product-term architectures, not mainstream FPGA combinational fabrics.

Common Pitfalls:
Confusing CPLD product-term macrocells with FPGA LUT fabrics. They achieve similar ends but with different internal structures.

Final Answer:
Look-up table