Explain resolution, accuracy and settling time with respect to DAC.
1 Answer

Resolution :

  • The resolution of a converter is the smallest change in voltage which may be produced at the output (or input) of the converter. For example, an 8-bit D/A converter has 2^8-1=255 equal intervals. Hence the smallest change in output voltage is(1/255) of the full scale output range.

  • Resolution should be high as possible. It depends on the number of bits in the digital input applied to DAC. Higher the number of bits, higher is the resolution.

  • It can also be defined as the ratio of change in analog output voltage resulting from a change of 1LSB at the digital input.

For n-bit DAC, $$Resolutions = \frac{V_{FS}}{2^n - 1}$$

Accuracy :

  • Absolute accuracy is the maximum deviation between the actual converter output and the ideal converter output.

  • Relative accuracy is the maximum deviation after gain and offset errors have been removed.

Settling time :

  • Settling time represents the time it takes for the output to settle within a specified band ±(1/2) LSB of its final value, after the change in digital input.

  • It should be as small as possible.

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