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Please image attached. Is there a mistake on the solutuion as it seem that for the PMOS Vgs = Vs-Vg?? Isn't it supposed to be Vgs = Vg-Vs?

Thanks PMOS Question

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  • \$\begingroup\$ Threshold voltage is term that is used for our convenience and its just a matter of interpretation. If you consdier Vgs of a PMOS then it would be a postive value of say -700mv but if you consider the threshold voltage as Vsg it would 700mV. In my opinion for calculations in order to maintain uniformity for N and Pmos we consider the threshold voltage to be +ve for both and thus Vsg is considered in your case to make the threshold of the Pmos a postive value . \$\endgroup\$ May 7 '16 at 12:58
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To turn on a P-channel enhancement mode MOSFET, the gate must be taken negative with respect to the source, so \$V_{gs}\$ is indeed Vs - Vg although I would agree it can be misleading and would more properly be named \$V_{sg}\$

This yieds the absolute value of \$V_{gs}\$

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