uu@uk wrote on Jun 16th, 2009, 10:19am:Hi,
The first one is the source follower. it is better to use to drive resistor and it cannot give you rail to rail output. The second one is usually the inverter driving capacitor and easily get a rail to rail output. Also, the second one, is saving power.
In addition the second one has a large gain, therefore it reduces the delay between input an output signal provided both drive the same load.