Hello David, there are Idsoff current specs in the datasheet. They have named it Idss and Igss. BSS84 Tj=25 degree: IDSS drain-source leakage current VGS = 0; VDS = -40 V -100 nA IGSS gate leakage current VDS = 0; VGS = ¡À20 V - - ¡À10 nA
The 2N7002 is modelled with about 0.6nA drain-gate leakage current. That is the reason why the output voltage is 280mV in the off state. The BSS84 is modelled with an Idoff current of about 20pA. You can conveniently probe this. Just do an .OP analysis and move the cursor to the pins. Watch the staus line at the bottom of the LTSPICE window.
