Explain Performance characteristics of D/A converters
1 Answer

Answer :

Some of the performance characteristics of D/A converters are as follows:

  1. Resolution

Resolution is defined as the number of possible output levels the DAC is designed to reproduce. This is usually stated as the number of bits it uses, which is the base two logarithm of the number of levels.

For instance a 1 bit DAC is designed to reproduce (21) = 2 levels while an 8 bit DAC is designed for (28) = 256 levels.

Resolution is related to the effective number of bits which is a measurement of the actual resolution attained by the DAC. Resolution determines colour depth in video applications and audio bit depth in audio applications.

  1. Maximum sampling rate

It is defined as measurement of the maximum speed at which the DACs circuitry can operate and still produce the correct output. Nyquist–Shannon sampling theorem defines a relationship between the sampling frequency and bandwidth of the sampled signal.

  1. Monotonicity

The ability of a DAC's analog output to move only in the direction that the digital input moves (i.e., if the input increases, the output doesn't dip before asserting the correct output.) This characteristic is very important for DACs used as a low frequency signal source or as a digitally programmable trim element.

  1. Total harmonic distortion and noise (THD+N)

A measurement of the distortion and noise introduced to the signal by the DAC. It is expressed as a percentage of the total power of unwanted harmonic distortion and noise that accompany the desired signal. This is a very important DAC characteristic for dynamic and small signal DAC applications.

  1. Dynamic range

A measurement of the difference between the largest and smallest signals the DAC can reproduce expressed in decibels. This is usually related to resolution and noise floor.

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