ASIC design categories overview: Four mainstream subcategories often cited for creating digital systems are PLDs, gate arrays, standard cells, and which additional category of customization?
Digital Electronics
Programmable Logic Device
Difficulty: Easy
Choose an option
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AHCPLDs
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Bfull custom
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CGAL
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DFPLDs
Answer
Correct Answer: full custom
Explanation
Introduction / Context: Application-Specific Integrated Circuits (ASICs) encompass multiple implementation styles. Understanding the four classic categories helps engineers weigh NRE cost, performance, time-to-market, and unit cost.
Given Data / Assumptions:
- Common categories include PLDs (programmable logic devices), gate arrays (semi-custom with prefabricated transistors), and standard cells (cell libraries placed and routed).
- A fourth category reflects maximum customization at the transistor/layout level.
- Terminology focuses on implementation style rather than vendor-specific branding.
Concept / Approach: The missing category is “full custom,” where every transistor and interconnect can be hand-crafted for optimal speed, power, and area. This approach has the highest NRE and longest development cycle but enables peak performance and density.
Step-by-Step Solution:
List known three → PLDs, gate arrays, standard cells.Identify the top-customization category → full custom ASIC.Therefore, the fourth category is “full custom.”Verification / Alternative check:
ASIC design textbooks consistently present these four tracks.Why Other Options Are Wrong:
HCPLDs: Not a standard ASIC category; CPLD is a PLD subclass, not separate in this quartet.GAL: A specific SPLD type, not an ASIC category.FPLDs: General term for programmable logic (e.g., FPGA/CPLD) already covered under PLDs.Common Pitfalls:
Confusing device families (e.g., GAL) with implementation categories.Thinking gate arrays include full-custom; they do not—they are semi-custom.Final Answer:
full custom