Analog-to-digital converter - Linear ADCs

An analog-to-digital converter (abbreviated ADC, A/D, or A to D) is a device that converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC). Typically, an ADC is an electronic device that converts a voltage to a binary digital number. However, some non-electronic devices, such as shaft encoders, can be considered as ADCs. Analog-to-digital converter - Resolution. The resolution of the converter indicates the ...

Including:

• Analog-to-digital converter - Resolution
• Analog-to-digital converter - Response type
• Analog-to-digital converter - Linear ADCs
• Analog-to-digital converter - Non-linear ADCs
• Analog-to-digital converter - Accuracy
• Analog-to-digital converter - Sampling rate
• Analog-to-digital converter - Aliasing
• Analog-to-digital converter - Dither
• Analog-to-digital converter - Oversampling
• Analog-to-digital converter - ADC structures
• Analog-to-digital converter - Application to music recording
• Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia - Analog-to-digital converter

These are the most common ways of implementing an electronic ADC: A direct conversion ADC or flash ADC has a comparator that fires for each decoded voltage range. The comparator bank feeds a logic circuit that generates a code for each voltage range. Direct conversion is very fast, but usually has only 8 bits of resolution (256 comparators) or less, as it needs a large, expensive circuit. ADCs of this type have a large die size, a high input capacitance, and are prone to produce glitches on the output (by outputtin ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - ADC structures

ADCs are integral to much current music reproduction technology, since much music production is done on computers; even when analog recording is used, an ADC is still needed to create the PCM data stream that goes onto a compact disc. The current crop of AD converters utilized in music can sample at rates up to 192 kilohertz. Many people in the business consider this an overkill and pure marketing hype, due to the Nyquist-Shannon sampling theorem. Simply put, they say the analog waveform does not have enough information in it to neces ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Application to music recording

In A to D converters, performance can be improved using dither. This is a very small amount of random noise (white noise) which is added to the input before conversion. Its amplitude is set to be about half of the least significant bit. Its effect is to cause the state of the LSB to randomly oscillate between 0 and 1 in the presence of very low levels of input, rather than sticking at a fixed value. Rather than the signal simply getting cut off altogether at this low level (which is only being quantized to a resolution of 1 bit), it extends ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Dither

All ADCs work by sampling their input at discrete intervals of time. Their output is therefore an incomplete picture of the behaviour of the input. There is no way of knowing, by looking at the output, what the input was doing between one sampling instant and the next. If the input is known to be changing slowly compared to the sampling rate, then it can be assumed that the value of the signal between two sample instants was somewhere between the two sampled values. If, however, the input signal is changing fast compare ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Aliasing

Analog-to-digital converter - Linear ADCs. Most ADCs are of a type known as linear, although analog-to-digital conversion is an inherently non-linear process (since the mapping of a continuous space to a discrete space is a non-invertible and therefore non-linear operation). In the sense of the term "linear" as used here, it means that the range of the input values that map to each output value has a linear relationship with the output value, i.e., that the output value k is used for the range of input values fro ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Response type

Accuracy depends on the error in the conversion. If the ADC is not broken, this error has two components: quantization error and (assuming the ADC is intended to be linear) non-linearity. These errors are measured in a unit called the LSB, which is an abbreviation for least significant bit. In the above example of an eight-bit ADC, an error of one LSB is 1/256 of the full signal range, or about 0.4%. Quantization error is due to the finite resolution of the ADC, and is an unavoidable imperfection in all types of ADC. The magnitude of the quantization error at t ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Accuracy

The analog signal is continuous in time and it is necessary to convert this to a flow of digital values. It is therefore required to define the rate at which new digital values are sampled from the analog signal. The rate of new values is called the sampling rate or sampling frequency of the converter. A continuously varying bandlimited signal can be sampled (that is, the signal values at intervals of time T, the sampling time, are measured and stored) and then the original signal can be exactly reproduced from th ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Sampling rate

The resolution of the converter indicates the number of discrete values it can produce. It is usually expressed in bits. For example, an ADC that encodes an analog input to one of 256 discrete values has a resolution of eight bits, since 28 = 256. 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 values. Some examples may help: Example 1 Full scale ...

See also:

Analog-to-digital converter, Analog-to-digital converter - Resolution, Analog-to-digital converter - Response type, Analog-to-digital converter - Linear ADCs, Analog-to-digital converter - Non-linear ADCs, Analog-to-digital converter - Accuracy, Analog-to-digital converter - Sampling rate, Analog-to-digital converter - Aliasing, Analog-to-digital converter - Dither, Analog-to-digital converter - Oversampling, Analog-to-digital converter - ADC structures, Analog-to-digital converter - Application to music recording, Analog-to-digital converter - Other applications

Read more here: » Analog-to-digital converter: Encyclopedia II - Analog-to-digital converter - Resolution