Linear Integrated Circuit Multiple Choice Questions on “DAC / ADC Specification”.
1. Find out the resolution of 8 bit DAC/ADC?
A. 562
B. 625
C. 256
D. 265
Answer: C
Clarification: The resolution is the value of LSB
Resolution =2n, where n-> number of bits
∴ Resolution =28=256 possible output values.
2. Non-linearity in the output of converter is expressed in
A. None of the mentioned
B. Percentage of reference voltage
C. Percentage of resolution
D. Percentage of full scale voltage
Answer: D
Clarification: Non-linearity is the measure of deviation of actual output (ε) from the ideal straight line output (△). Therefore, it is expressed as percentage of full scale voltage (ε/△).
3. A binary input 000 is fed to a 3bit DAC/ADC. The resultant output is 101. Find the type of error?
A. Settling error
B. Gain error
C. Offset error
D. Linearity error
Answer: C
Clarification: Offset error implies that the output of the DAC is not zero when the binary inputs are all zero.
4. How many equal intervals are present in a 14-bit D-A converter?
A. 16383
B. 4095
C. 65535
D. 1023
Answer: A
Clarification: A 14-bit D-A converter has 2n-1 equal interval =214-1=16384-1=16383.
5. Resolution of a 6 bit DAC can be stated as
A. Resolution of 1 part in 63
B. 6-bit resolution
C. Resolution of 1.568% of full scale
D. All of the mentioned
Answer: D
Clarification: Resolution of 6 bit DAC =VFS% /(2n-1) =(VFS×100)/(26-1) = 1.588% of VFS and the number of interval is 26-1=63.
=> Thus, resolution of a 6 bit DAC can be stated as a resolution of 1 part in 63.
6. Find the resolution of a 10-bit AD converter for an input range of 10v?
A. 97.7mv
B. 9.77mv
C. 0.977mv
D. 977mv
Answer: B
Clarification: Resolution (in volts) VFS /(2n -1)= 10 /(210 -1) =10/1023 =9.77mv.
7. A good converter exhibits a linearity error
A. Less than or equal to (1/2)LSB
B. Greater than equal to (1/2)LSB
C. Greater than or equal to (1/2)LSB
D. None of the mentioned
Answer: D
Clarification: A good converter exhibits a linearity error of less than ±(1/2)LSB.
8. The maximum deviation between actual and ideal converter output after the removal of error is
A. Absolute accuracy
B. Relative accuracy
C. Relative /absolute accuracy
D. Linearity
Answer: B
Clarification: Relative accuracy is the maximum deviation after gain and offset error has been removed.
9. A monotonic DAC is one whose analog output increases for
A. Decreases in digital input
B. An increases in analog input
C. An increases in digital input
D. Decreases in analog input
Answer: C
Clarification: In a DAC, the analog input is converted into digital output. So, a monotonic DAC increases its analog output with increase in its digital output. For example, if the output decreases when input code change from 001 to 010, it is said to be a non-monotonic DAC.
10. All the commercially available DAC are
A. Monotonic
B. Non-monotonic
C. Either monotonic or non-monotonic
D. None of the mentioned
Answer: A
Clarification: All the commercially available DACs are monotonic because the linearity error never exceeds ± (1/2) LSB at each output level.
11. The time taken for the output to settle within a specified band of its final value is referred as
A. Conversion time
B. Settling time
C. Take off time
D. All of the mentioned
Answer: B
Clarification: Settling time represents the time taken for the output to settle within a specified band ± (1/2) LSB of its final value following a code change at the input (usually a full scale change).