Advantages:-

I) A large no.of comparator are required to be used. For the 2 bit ADC , 3 comparators are used a 3 bit requires 7 comparators and 4-bit requires 15 comparators

n bit requires 2$^{n-1}$ comparators

No of comparators required almost doubles for each addded bit

iii) with increased no.of bits “n” the priority encoder becomes increasingly complex