questions about buffer selecting

[wereiyou]

In which condition should I use a buffer for the signal, such as a clock buffer. Can anybody give me some draft ideas?

 

[The Joy of Electronics]

In conditions where there's a possibility of the desired signal to be significantly attenuated due to improper input resistance.

 

[ahmed_nasr]

In case of analog applications , buffer is used as the input stage of the amplifier so that it has infinite i/p impedance and zero o/p impedance and hence gain isnt reduced

For digital appliacations ... which is your case i guess coz u are talking about clock buffer .... we use buffers to drive large capacitive loads to reduce propagaton delay of the digital signal as these buffers are large in size --> have low output resistance .... so delay=0.69*R*C will be small