Spikes on my signal

Hi

I was working on RF Receiver and i finished it but the output data has spikes on it due to using multiplexer at the end.

" The output was like (00 01 10 11) and i wanted to convert it to pam4 signal levels like (0 0.166 0.33 0.5)"

So while using the multiplexer and during edges transactions spikes are found due to fall and rising times...

Is there a way or circuit to remove those spikes..