---
title: "Full-custom IC advantages and disadvantages"
subject: "Embedded System"
chapter: 8
key: "semester_6/embedded_system:full-custom-pros-cons"
source: https://www.bctengineer.com/q/semester_6/embedded_system/full-custom-pros-cons
site: BCT Engineering
---

# Full-custom IC advantages and disadvantages

Embedded System · Chapter 8: IC Technology

- Asked in: 2072 Asoj, 3 marks; 2078 Chaitra (asked 2 times)
- Video: [Module-4, Lecture-8, Microcontroller & Embedded System: Full Custom / VLSI, Semi Custom ASIC](https://www.youtube.com/watch?v=Z1CqrvEl0pE) — Dr. SANGITA ROY
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/embedded_system/full-custom-pros-cons
- Whole chapter: https://www.bctengineer.com/md/semester_6/embedded_system/chapter-8

## Question

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

## 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.

## Answer

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).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Advantage?
   A. Low NRE
   B. Short design
   C. Best speed and lowest power
   D. Changeable
   Answer: C. Hand-tuned. (Key point: Advantage)

2. Disadvantage?
   A. Low performance
   B. Very high NRE and long design time
   C. Large area
   D. No IP protection
   Answer: B. Full mask set. (Key point: Disadvantage)

3. Economical when?
   A. Very high volumes like microprocessors
   B. Prototypes
   C. Low volume
   D. One-off
   Answer: A. NRE amortised. (Key point: Volume)

## Related in Embedded System

- [Full custom VLSI technology](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Afull-custom-vlsi-brief) — Embedded System, chapter 8
- [Two categories of semi-custom IC](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Asemi-custom-two-categories) — Embedded System, chapter 8, asked 2×
- [Full-custom, semi-custom and PLD design steps](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Afull-semi-custom-pld-steps) — Embedded System, chapter 8, asked 2×
- [Semi-custom ASIC and manufacturing steps](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Asemi-custom-asic-types-manufacturing) — Embedded System, chapter 8

## Related in other subjects

- [Why switched capacitors in IC; summer and integrators](https://www.bctengineer.com/question.md?key=semester_5%2Ffilter_design%3Asc-ic-summer-integrators) — Filter Design, chapter 9
- [Why SC in IC; resistor simulation; summer and integrators](https://www.bctengineer.com/question.md?key=semester_5%2Ffilter_design%3Asc-resistor-summer-lossy-noninverting) — Filter Design, chapter 9