Does SGA and PGA memory goes hand-in-hand

We are on 11.2.0.3 database and we have a situation on this database where OEM advisory shows that our DB requires an increase in SGA to 17 GB but the PGA is perfectly fine. On this version , we have set the below parameters in the spfile as follows :

sga_target=9 GB

pga_aggreegate_target=4GB 

So my questions to the forum member is as follows ==> 

Que 1) If i approximately doubles the SGA of my system from 9 GB to 17 GB , then would that have any effect on my PGA?  Also, does increase in SGA also mandates increase/decrease in corresponding PGA as well.