If i am using QPSK modulation with data rate 4 Mbps with rolloff factor $0.5$, then the bandwidth will be symbol $\rm rate\times (1 + rolloff\ factor)$. So here it will be $\rm 2\ MHz\times 1.5 = 3\ MHz$
This is baseband data bandwidth.
So should I use analog filter of bandwidth $\rm 3\ MHz$ or should it be more? or should it be more than that?