nmos G/S/B connected to gnd

[yann_sun]

Hi all,
I've seen a nmos whose G/S/B are all connected together to gnd.
What is that used for?
Thanks.

 

[erikl]

Either a dummy transistor to provide continuous environment for transistors to be matched,
or a spare transistor for optional use in a possible redesign, usually recognizable by its gate & drain connections brought to top (or second to top) metal layer and only there connected to GND.

 

[ducvilla]

When you connect G/S/B of NMOS to gnd, it will act like capacitor.

 

[erikl]

When you connect G/S/B of NMOS to gnd, it will act like capacitor.

Yes: a short-circuited capacitor! :roll:

 

[jarillak]

Hi to all......
When the four terminals(D,G,S,B) of MOS(both NMOS & PMOS),it will acts as adummy.These dummies are useful in MOS layout matching concept which will protect active MOSFETs from etching during fabrication.Normally dummies are kept at edges of matced MOSFETs.

Sometimes MOSFET can be used as capacitor in which three terminals(D,S,B) connected with one potential and the remaining one terminal(G) is connected with another potential.

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Hi to all......
When the four terminals(D,G,S,B) of MOS(both NMOS & PMOS),it will acts as adummy.These dummies are useful in MOS layout matching concept which will protect active MOSFETs from etching during fabrication.Normally dummies are kept at edges of matced MOSFETs.

Sometimes MOSFET can be used as capacitor in which three terminals(D,S,B) connected with one potential and the remaining one terminal(G) is connected with another potential.