I have designed a PMOS (FDN306) based power on off switch. When I turn off the switch by connecting gate and source (via Schmitt Trigger), I see a output voltage of 50mV. This is with 3.9V Source voltage. If I increase the source voltage to 5V, the output voltage goes down to 20mV. I check the Gate and Source voltage and I see them identical.
I don't have the schematic in this computer but it is essentially a super simple switch. It sounds like, I didn't choose the right PMOS.
What type of PMOS I should choose? Why there is a significant leakage out of PMOS in this case?