I dont know what is happening here. Both PMOS and NMOS have

W=100*270nm L=180nm Vgs=1.8v vds=1.8v

while NMOS is carrying only 14.19mA current, How can PMOS carry 15.97mA for the same size and Voltages ?

enter image description here

  • 1
    \$\begingroup\$ huh, I have the raw opposite in the back of my head: N-Channel mosfets can carry more current than P-Channel MOSFETs at the same dimension. \$\endgroup\$ Commented Jun 9, 2016 at 20:39
  • \$\begingroup\$ I think you have a bad model. try a drain sweep. it's as if the pinch off value is off \$\endgroup\$
    – b degnan
    Commented Jun 9, 2016 at 22:07

2 Answers 2


In your NMOS case the voltage source is mentioned correctly with the total current but in the second PMOS image it does not match. And also the Vgs of both should not be same because for the PMOS Vsg refers to a positive threshold. Try this, connect the ground that is in your image which is connected on top(source) to the bottom which is the drain (Symbols are reverse in PMOS compared to NMOS I hope you are considering this, the top is Source and the bottom is drain unlike in NMOS).

Make sure your PMOS source terminal is connected to a +ve voltage and your drain connected to the -ve of both the voltage sources(gate and source) and place the gnd at the bottom of the PMOS which is the drain. Now you should measure a current less than the NMOS case because mobility of holes is lesser compared to the mobility of electrons.


I'm not quite sure you're looking at this the right way, but anyway:

P- and N-Channel MOSFETs are different in how the respective semiconductor need to be doted and sized for the same current. Due to that physical difference, device of the same dimensions but different channel type will be able to carry a different current.


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