Microelectronic Design

Unit 1 - Integrated Circuit Design Process (Overview)

Question 1

The correct order is:

Specification
Technology and Structure
System Design and Partitioning
Create Cells
Simulation

Question 2

Safe limit is 10⁹ A/m²

$J = \frac{I}{Wt}$

$W = \frac{I}{Jt} = \frac{50\times10^{-3}}{10^{9} \times 5 \times 10^{-6}} = 10\mu m$

For a 20% safety margin

W - 10µm + 20% = 10µm + 2µm = 12µm

Question 3

$R = \frac{rL}{W\times t} = \left(\frac{1}{3 \times 10E7}\right)\times\left(\frac{10E-3}{12E-6 \times 5E-6}\right)$

R = 5.56ohms

V = I × R
V = (50 × 10) × 5.56
V = 0.28V

Question 4

8" wafer has an area of 32,429mm².

This gives 32429/20 = 1621 die.

Taking yields into account gives 1621 x 0.9 x 0.9 = 1313 good die.

Each device costs £300/1313 = 23p.

Packaging = 25p.

Testing costs @ 30% production costs = 14p.

Total device product cost = 62p.

At a production level of 100,000 units per year, production cost is 100,000 x 62 = £62,000 per year or £310,000 over five years.

Thus total cost over five years = £310,000 + £200,000 (design) + £100,000 (tooling costs) = £610,000.

Taking into account the required profit, the sales have to generate an income of £610,000 + £400,000 over 5 years = £1,010,000.

Let the initial sale price be x and reduces by 10% each year.

So income generated is £100,000x + £90,000x + £81,000x + £72,900x + £65,600x = £409,510x

The total income generated has to equal £610,000 + £400,000 = £1,010,000.

Therefore the initial selling price is £1,010,000/£409,510 = £2.47.

Question 5

Months	Costs	Income	Net
After 3	£200,000 + £100,000 = £300,000	£0	-£300,000
After 6	First 3 months' production 25,000 × 62p = £15,500	£0	-£315,500
After 9	Further 3 months' production 25,000 × 62p = £15,500	25,000 x £2.26 = £56,500	-£274,500
After 12	Further 3 months' production 25,000 x 62p = £15,500	25,000 x £2.26 = £56,500	-£233,500
After 15	Further 3 months' production 25,000 x 62p = £15,500	25,000 x £2.26 = £56,500	-£192,500
After 18	Further 3 months' production 25,000 x 62p = £15,500	25,000 x £2.26 = £56,500	-£151,500
After 21	Further 3 months' production 25,000 x 62p = £15,500	22,500 x £2.26 = £50,850	-£116,150
After 24	Further 3 months' production 25,000 x 62p = £15,500	22,500 x £2.26 = £50,850	-£80,800
After 27	Further 3 months' production 25,000 x 62p = £15,500	22,500 x £2.26 = £50,850	-£45,450
After 30	Further 3 months' production 25,000 x 62p = £15,500	22,500 x £2.26 = £50,850	-£10,100
After 33	Further 3 months' production 25,000 x 62p = £15,500	20,250 x £2.26 = £50,850	£20,165
	BREAK EVEN
After 36	Further 3 months' production 25,000 x 62p = £15,500	20,250 x £2.26 = £50,850	£50,430
After 39	Further 3 months' production 25,000 x 62p = £15,500	20,250 x £2.26 = £50,850	£80,695
After 42	Further 3 months' production 25,000 x 62p = £15,500	20,250 x £2.26 = £50,850	£110,960
After 45	Further 3 months' production 25,000 x 62p = £15,500	18,225 x £2.26 = £41,188	£136,648
After 48	Further 3 months' production 25,000 x 62p = £15,500	18,225 x £2.26 = £41,188	£162,336
After 51	Further 3 months' production 25,000 x 62p = £15,500	18,225 x £2.26 = £41,188	£188,024
After 54	Further 3 months' production 25,000 x 62p = £15,500	18,225 x £2.26 = £41,188	£213,712
After 57	Further 3 months' production 25,000 x 62p = £15,500	16,402 x £2.26 = £37,069	£235,281
After 60	Further 3 months' production 25,000 x 62p = £15,500	16,402 x £2.26 = £37,069	£256,850
After 63	£0	16,402 x £2.26 = £37,069	£293,919
After 66	£0	16,402 x £2.26 = £37,069	£330,988