> Okay, if I were to do something like this: (attached as png)

> Where would I connect the common source to? Would I put a 1M resistor to
> GND, so that the gate to source voltage is referenced to GND? Is that
> necessary? Or would this work as it is shown in the pic?

Sources can float as shown in your diagram.
When FETs are on then both drains and both sources are at essentially
the same potential.
As long as gate drive is high enough above this common potential when
on to ensure that FETs are fully turned on then the circuit will work.

Turn off gate drive voltage needs to be low enough for Vgs to be sure
to be below Vth for both FETs.

In some cases notionally the circuit may not "start" as the center
sources are floating but in practice this always seems to work well.
No doubt this is fully explicable when all parameters are considered
:-).

Usually this back to back arrangement is most economical but you may
wish to check if a separate P Channel and N Channel FET with each
turned on as required would be better in your case. This applies only
of Vin and Vout always have same relative potential. If Vin and Vout
can reverse relative polarity you either need back to back FETs as
above or a reverse diode in series with two separate P & N Channel
FETs.



            Russell
--=20
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