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digital to analoge converter (DAC)

DA converters (D/A), digital-to-analog converters or digital-to-analog converters (DAU) are electronic circuits for converting a digitally coded quantity into an analog current or voltage waveform. The ideal DA converter generates the analog output voltage from the binary

input code, with a linear relationship between the two quantities.

The structure of digital-to-analog converters

The entire conversion of a digital word into an analog signal takes place in several stages. First, the digital word is converted into individual analog voltage values in the actual DA converter. R-2R converters, pulse width modulation (PWM) converters or others are used for this conversion. The voltage at the output has a staircase shape. In the following stage, the stair-stepped signal is smoothed. This can be done by a sample and hold (S/H) circuit or with filters

Digital-to-analog conversion

Digital-to-analog conversion

Resampling in a sample-and-hold circuit reduces the pulse width. The stepped signal is then reconstructed and smoothed in a low-pass filter, which must have a cutoff frequency equal to half the sampling frequency. Filtering cuts off the higher frequencies and harmonics

, as well as the frequencies that are present around thesampling rate

Important parameters of DA converters

Block diagram of a D/A converter

Block diagram of a D/A converter

Important parameters of

D/A converters include accuracy, which depends on the data word length of the digital input signal, conversion speed

andconversion time, and noise

marginand distortion. As with the AD converter, the signal-to-noise ratio of the D/A converter depends on the word length of the digital word, while the distortion factor depends on the converter linearity. The resolution of DA converters on the market is between 8 bits and 24 bits, in some cases

even 32 bits can be achieved. DA converters are used in audio and video technology.

For example, in CD and DVD drives, in MP3 players, mobile phones, telephones and smartphones.

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Englisch: digital to analoge converter - DAC
Updated at: 12.03.2020
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Translations: DE