[HN Gopher] Reverse-engineering a vintage comparator chip
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       Reverse-engineering a vintage comparator chip
        
       Author : parsecs
       Score  : 6 points
       Date   : 2021-04-17 17:33 UTC (5 hours ago)
        
 (HTM) web link (www.righto.com)
 (TXT) w3m dump (www.righto.com)
        
       | PhantomGremlin wrote:
       | _Much of the die is unused, especially the large metal area in
       | the middle._
       | 
       | I don't think the word "unused" is appropriate.
       | 
       | 1) Probably they wanted to physically separate the comparators,
       | for better noise isolation between them.
       | 
       | 2) the large metal area is connected to V+. By using such a large
       | amount of metal they get slightly lower voltage drop in their
       | power distribution.
       | 
       | 3) But here's what I think is the main reason. The metal is being
       | used as a power decoupling capacitor. I can't be sure of what's
       | underneath, but most likely the area is connected to V-. Voila!
       | You couldn't possibly get a decoupling cap any closer to where
       | it's needed than that.
        
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       (page generated 2021-04-17 23:01 UTC)