Question

1. An A/D converter will convert voltages over a 0 to 10 V range. How many bits must it be to achieve a 1 mV resolution over the entire range? 2. You have an A/D converter that will convert over a range of 0 to 5 V. You input an analog signal to it that has a range of 1 to 3.5 V. What must be the number of bits of the converter to achieve a resolution of 1% of the maximum signal value? 3. You have and 8 bit A/D that converts over the range of 0 to 5 Volts. What will be its output if an analog voltage of 3.28 volt is the input? 4. You have a flash A/D that has an output of 5 bits. How many comparators does in have inside? 5. The minimum acquisition time for an A/D is 20 microsecond. What is the highest frequency that the signal can contain so that it is sampled without violating the sampling theorem?

Answer 1

1. Resolution of an A/D converter is given by resolution = Input voltge range (N- no. of bit's of ADC) 15%= to 99=104 [n=14] 1% of mox signal value = 1 x 5 = 0.05 0.05 = 3.500 2n = 50 [026] Digital output= ceil ( Input voltge I ADC resolution) resolution = 5 18 Bigo oppis ceil ( 3320 x 25) = ceil(167.9) bizi.op - (168)16 ie pig % = (10101000)

The flash no. of Comparators in an 'N' bit ADC contain = (@^-1) so, 5 bit flash ADC contains = (251) = 31 comparators. acqua siattion time < Is 20x16% = 24 2 lords=24] famosi = 25 kha 20