Required supply voltage for common source.

[hanhan]

Hi, please help me with this section from my text book about power amplifier.
I am confused about the highlighted part. With common source, how can you know about the required voltage for power supply?
For example, in the example, they said that the configurations shown in Fig. 12.1 (a), (b) require a supply voltage greater than Vpp. And in case the load is realised as an conductor, I really don't understand what they say. Please help me explain it more detail.

 

[MrAl]

Hi,

I dont see any circuit, i think you should post it here.

 

[hanhan]

Hi,
The circuit is posted in the post. I can see it now. Maybe the site has problems.
I am posting it again. Please help me understand it.
Thanks.