delay lock loop
the main issue about the PLL and the DLL , is the DLL change the delay , but the PLL change the phase and frequency ,
if u want the DLL to change the freququncy , u should use an delay line , and a edge combiner , in this case the DLL can change frequency , so it can be used to demodulated the FM singal ,
u need to read about how DLL can be used as Freq synthsizer , it can guide
the DLL gone need some twaeking to work as FM demodulator , good luck
khouly