Hello All,
I am simulating a switch circuit using mosfets. I simulated two circuits. One with the mosfet on the low side and one with it on the high side. The mosfet is an NMOS FDC637AN. I chose this at random just because it was in the library. When the mosfet is placed on the low side the current is significantly higher than when placing it on the high side. When I do the math, it appears that the mosfet is in the triode region Vds<Vgs-Vth. Probing around the circuit Vds is .037V when placed in the low side configuration and 1.48 when placed in the high side configuration. I am stuck understanding why this is happening. Can someone please explain why the mosfet is able to pass more current when placed in the low side configuration? I have attached an image of the circuit that I simulated.
I am simulating a switch circuit using mosfets. I simulated two circuits. One with the mosfet on the low side and one with it on the high side. The mosfet is an NMOS FDC637AN. I chose this at random just because it was in the library. When the mosfet is placed on the low side the current is significantly higher than when placing it on the high side. When I do the math, it appears that the mosfet is in the triode region Vds<Vgs-Vth. Probing around the circuit Vds is .037V when placed in the low side configuration and 1.48 when placed in the high side configuration. I am stuck understanding why this is happening. Can someone please explain why the mosfet is able to pass more current when placed in the low side configuration? I have attached an image of the circuit that I simulated.