PO approval Route

I would like to know if there is a way to have a PO being approved if the originator of the PO is also an approver without going to above approver.

Suppose this route

approval      Responsible

amount    

100            Dwight Akin

1000          Ray Allen

5000          Dominique Abbot

Ray Allen create a PO of 50$.  We would like to have PO automatically approved because the amount is less then the first approver limit.

Ray Allen create a PO of 200$. We would like to have PO automatically approved because the amount is less then  Ray limit.

Ray Allen create a PO of 2500$. We would like to have PO automatically approved because the amount is less the next approver limit.