Consider the following situation:
There is a capacitor C1 (polarity does not matter). The 'top plate' of the capacitor is the one at the top of the diagram and has two ideal switches connected, one connecting to ground during φ1 and one floating at φ2.
The bottom plate also has two ideal switches, one connecting to Vin during φ1 and one connecting to ground during φ2.
In phase 1, the capacitor is charged to Vin with polarity as shown in the diagram. The bottom plate has +Q charge and the top plate has -Q charge.
In phase 2, the bottom plate of the capacitor is switched to ground and the top plate is switched to the floating node, thus a voltage of -Vout will appear at the floating node as the capacitor will maintain the charge.
At the end, the capacitor no longer has +Q and -Q on each of it's plates, it kind of has -Q and -2Q. The positive charges that were at the bottom plate should all go to GND and thus to maintain the same charge across the capacitor (Q=CV), the top plate charge should go more negative.
Where does the top plate receive these extra electrons from? Is it just from the metal of the wire and hence no current actually flows?
My question is really about the polarity of the charges on the capacitor as we go into phase 2. I've always struggled with this.