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Analog digital converter

Analog digital converter. Curs XIII. Definitie. An analog-to-digital converter (abbreviated ADC , A/D or A to D ) is an electronic circuit that converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC).

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Analog digital converter

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  1. Analog digital converter Curs XIII

  2. Definitie • An analog-to-digital converter (abbreviated ADC, A/D or A to D) is an electronic circuit that converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC).

  3. Rezolutia • The resolution of the converter indicates the number of discrete values it can produce over the range of voltage values. The values are usually stored electronically in binary form, so the resolution is usually expressed in bits. In consequence, the number of discrete values available, or "levels", is usually a power of two. For example, an ADC with a resolution of 8 bits can encode an analog input to one in 256 different levels, since 28 = 256. The values are usually a range of from 0 to 255 or from -128 to 127, for example, depending on the application. • Resolution can also be defined electrically, and expressed in volts. The voltage resolution of an ADC is equal to its overall voltage measurement range divided by the number of discrete intervals as in the formula:

  4. Rezolutia • Example 1 • Full scale measurement range = 0 to 10 volts • ADC resolution is 12 bits: 212 = 4096 quantization levels • ADC voltage resolution is: (10-0)/(4096-1) = 0.00244 volts = 2.44 mV • Example 2 • Full scale measurement range = -10 to +10 volts • ADC resolution is 14 bits: 214 = 16384 quantization levels • ADC voltage resolution is: (10-(-10))/(16384-1) = 20/16383 = 0.00122 volts = 1.22 mV • In practice, the resolution of the converter is limited by the signal-to-noise ratio of the signal in question. If there is too much noise present in the analog input, it will be impossible to accurately resolve beyond a certain number of bits of resolution, the "effective number of bits" (ENOB). While the ADC will produce a result, the result is not accurate, since its lower bits are simply measuring noise. The signal-to-noise ratio should be around 6 dB per bit of resolution required.

  5. Precizia • Erori de quantizare • Erori de neliniaritate • -integrale • -diferentiale

  6. Erori de apertura

  7. Nyquist–Shannon sampling theorem

  8. Spectru semnalului esantionat

  9. Alierea frecventelor

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