Probably a dumb question here.. but.. what happens to the DC characteristics of, say, a p-channel MOSFET if I pull the bulk potential above the source by a few volts? Will Id vs. Vgs change much?
Best regards, Spehro Pefhany
Not a dumb question at all. It moves the channel around similar to the gate, so transconductance and threshold change.
Do you have a specific type in mind? Does it have a model available?
Let me know. If you don't have a model I can run a generic device and post the plots so you can see what it looks like.
...Jim Thompson
That would be great.
These guys, which have common bulk:
I see a plot of changes vs. *substrate* bias but not bulk-- all the specs are at Vbs = 0. These parts are nicely specified for analog applications.
My idea is to use these as pass transistors for a number of independent high precision 10uA current sources of both polarities. Will current flow in or out of that pin? I was thinking to connect it to a voltage 2.5V beyond the rail.
Best regards, Spehro Pefhany
^^^^^ oops, make that "source" Best regards, Spehro Pefhany
You might also look at the SD5400 datasheet. A decade ago I've used them a lot for such stuff because the substrate was brought out on a separate package pin. Then they became boutiqueish and expensive :-(
Here you go....
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
Thanks, Jim! Exactly what I need.
Best regards, Spehro Pefhany
You're welcome!
When are you and "C" coming to Phoenix again?
...Jim Thompson
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