loose-electron
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Best Design Tool = Capable Designers
Posts: 1638
San Diego California
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matching in a large power transistor is important in the bipolar world, but not as much in the CMOS world.
CMOS devices are self balancing to get equal current thru all parallel devices. Bipolar devices are not.
Two things on geometry with the pass transistor - 1. Keep the transistor width short enough so that the gate stripe resistance does not become an issue. (its an RC time constant thing, go figure frequency of the control signal vs. RC of the gate across the transistor width. 2. Extensive well tie ups are needed to keep the bulk tied to the positive power.
With those 2 things, you end up breaking the transistor into an array of smaller devices tied in parallel.
jerry
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