In this paper, the authors introduced a 4 bit flash analog to digital converter. The propose ADC consist of the comparators and the MUX based decoder. Propose comparator eliminate the use of resistor ladder in the circuit. All the input of comparators is connected to the common input node. Depending upon the internal voltage of comparator and the input voltage output may be “0” or “1” known as thermometer code. This thermometer code is converted to the binary code using the MUX based decoder.