Test: Data Converters - 1 - Electronics and Communication Engineering (ECE) MCQ

Concept:

The resolution for n bit DAC is given by:

The % resolution for n bit DAC is given by:

Calculation:

n = 8

% R = 0.39

The full scale output voltage of the given step size δ is:                             

V_fs = (2ⁿ−1) x δ where n is the number of bits

Now ,for question n = 8 and δ = 20 mV

V_fs = (2⁸ − 1)×20×10⁻³

V_fs = 5.1 V

Concept:

The resolution of either a digital-to-analog converter (DAC) or an analog-to-digital converter (ADC) is the measure of how finely its output may change between discrete, binary steps.

For an n-bit DAC, the resolution (R) is measured by:

V_out = Output Voltage

n = number of bits

Calculation:

With V_out = 5 V, and n = 8 bits, the resolution will be:

Resolution = 0.0196

No of comparators required for n bit flash type ADC is (2ⁿ - 1)

Given that, n = 12

No of comparators = 4095

Resolution: It is defined as the smallest change in the analog output voltage corresponding to a change of one bit in the digital output.

The percentage resolution (%R) of an n-bit DAC is:

The resolution of an n-bit DAC with a range of output voltage from 0 to V is given by:

Calculation:

Number of bits (n) = 8

Resolution = 

Concept of Resolution: 

It is defined as the smallest change in the analog output voltage corresponding to a change of one bit in the digital output.

The percentage resolution (%R) of an n-bit DAC is:

Calculation:

As we know the formula resolution,

250 = 2^N -1

2^N = 251 ≈ 255 

i.e., 2⁸ = 255

N = 8

Hence the minimum value of N satisfying the condition.

Concept:

• Analog-to-Digital Converters (ADCs) transform an analog voltage to a binary number (a series of 1’s and 0’s).
• Then eventually to a digital number (base 10) for reading on a meter, monitor, or chart.
• The ADC resolution depends upon the number of bits used to represent the digit number. 
• As the number of bits increases the resolution of an Analog to Digital Converter improves and the quantization error decreases.

Resolution for n – bit A/D converter  will be:

Where 

R = Resolution

VFS is reference voltage 'or' Full-scale voltage

n = number of bits

2ⁱbⁱ gives output voltage value.

Calculation:

Given:

V_FS = 5.8 V

n = 4

R = 05 V

2ibi = 12.93 V ≈ 12 V

In bits, the output voltage will be 1100

Hence option (A) is the correct answer.

Concept:

Maximum error (E_r) of D/A is given as,

E_r = (V_FS x Accuracy)

Where,

V_FS: full-scale input voltage

Calculation:

Given: V_fS = 5V , Accuracy= 0.2%

E_r = 10 mV

Counter type ADC:

• Counter-type ADC is very simple to understand and also easy to operate.
• Counter-type ADC design is less complex, so the cost is also less.
• ·Speed is less, since each time the counter has to begin from ZERO.
• There may be conflicts if the next input is sampled before the completion of one process.
• In a Counter type ADC, the conversion time varies.

Resolution: It is defined as the smallest change in the analog output voltage corresponding to a change of one bit in the digital output.

The percentage resolution (%R) of an n-bit DAC is:

The resolution of an n-bit DAC with a range of output voltage from 0 to V is given by:

Calculation:

Full scale output voltage (V) = 10 V

Number of bits (n) = 8

Resolution = 

%R = 1 / 255 × 100 = 0.392 %