Direct Type:-

Under direct type ADC, the analog I/p voltag is compared with the certain ref voltage & then with the encoding circuit. It is considered to be single step conversion

The ADC’S are faster than indirect type. But o/p voltage is sensitive to noise . It is widely used in common , particularly for data conversation as pcm signal

Indirect type:- It is two step analog to digital conversation It converts the analog i/p into a linear fun. of time which in turn produces the timing signal . It has either variable time period or the fixed time period . The timing signal is converted into equivalent digital word

It is slower than direct type but has better noise rejection