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Full-custom IC advantages and disadvantages

Short answer

Full-custom design yields best performance, lowest power and smallest area, but incurs very high NRE cost and long design time. It is economical only for high-volume products like microprocessors, and design errors require a new mask set.

Discuss the advantages and disadvantages of full-custom IC technology.

In full-custom IC technology all layers, including every transistor and its layout, are designed by hand for the specific chip, and every mask is made specially for it.

Advantages

  • Best performance: highest speed, because transistor sizes and wire lengths are tuned.
  • Lowest power consumption.
  • Smallest chip area for the function, so low unit cost at high volume.
  • Full freedom: mixed analog and digital circuits and special cells can be put on one chip.
  • Good intellectual-property protection.

Disadvantages

  • Very high NRE (non-recurring engineering) cost: design, tools, full mask set.
  • Very long design time (months to years), delaying time to market.
  • Hand layout needs highly skilled engineers; high risk of errors.
  • Any error needs a new mask set and re-fabrication; the design cannot be changed after fabrication.
  • Economical only for very high volumes (e.g. microprocessors, memory).

✓ Answer checked by Claude Opus 5.5 (high effort)

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