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I was simulating a P MOSFET, and for turning a P MOSFET on we need gate to Source voltage less then its threshold voltage. as per below simulation circuit at start VGS= 0, then there is no way mosfet get turn on,because it need at least -2V as per datasheet gate thershold to turn it on. but simulation i am getting 4V arroud, whats wrong here. enter image description here

Some Might say i applied voltage VDS=5V but for P MOSFET it should be negative, but i saw some circuit where they used this type of connection where R1 is just replaced by a supercap.

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Do you know that every MOSFET has a build in body diode between the drain and the source? In your case, the anode of a body diode is connected to the drain terminal and the cathode to the source terminal. And this is why your MOSFET is turn-ON.

Your circuit

schematic

simulate this circuit – Schematic created using CircuitLab

The proper way to turn on the P-Channel MOSFET looks like this

schematic

simulate this circuit

And now pushing the SW1 switch will Turn ON the MOSFET. And releasing the switch will turn-OFF the MOSFET. Notice that the source terminal is connected to the highest potential in the circuit. And body diode will not conduct.

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There is a diode between source and drain on MOSFETS. It is not always drawn in the symbol, but it is there.

schematic

simulate this circuit – Schematic created using CircuitLab

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