An acidic buffer is prepared by mixing :

Preparation of acidic buffer:
Mixiture of weak acid and its salt with strong base is called acidic buffer it is prepared by
(i) taking more amount of weak acid and less amount of strong base. 
$\therefore$ meq of weak acid > meq of strong base
On titration, strong base is completely neutralised and the mixture contains mixture of weak acid (unreacted) and its salt with strong base.
(ii) meq of salt of weak acid and its salt >>> meq of strong acid
Strong acid displaces weak acid from its salt. When meq of strong acid taken is less, after reaction unreacted salt and weak acid formed is present. It is an acidic buffer solution.