Inside the 741 op-amp.

dl324

Joined Mar 30, 2015
11,230
That was back in the day when pattern generator flash counts were low enough that no one worried about the cost and time it took to pattern circles on the masks.
 

dl324

Joined Mar 30, 2015
11,230
Could you explain more about pattern generator flash counts?
When the pattern generator was used to convert the layout to data that was used to generate the masks (quartz plates used to expose the wafers), the polygons were fractured into trapezoids. Circles required large numbers of trapezoids to approximate them. The manufacturers charged a certain amount (my recollection is around a penny) per flash (exposure). Since it also took longer to make the mask, they would sometimes have a surcharge for time.
 

WBahn

Joined Mar 31, 2012
26,037
Nice article. I also particularly liked the interactive graphic. As an IC designer, I would LOVE to make graphics like that for our chips. It could really be useful in a number of ways. But it would need to be automatically generated (or at least almost completely so) in order for the effort to be worth it.
 
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