Data Converters Overview

What Are Data Converters?

Data converters come in two varieties, described in greater detail below. In general terms a data converter is a device that converts analog signals to digital data or vice versa. Devices that convert analog signals to digital are frequently referred to as ADC. Devices that convert digital signals to analog are called DAC.

Data converters come in many different architectures and are used for a wide variety of different purposes.


What Are Data Converters Used For?

DAC and ADC devices each have their own uses, but both are vital technologies for the digital age. They make many of the luxuries with which people are familiar possible, and also play significant roles in scientific, telecommunications and other applications.

Digital to analog converters are mainly used in audio and video applications. They are also used in mechanical applications, but their use in A/V is demonstrative of what these devices offer in terms of the benefits of converting analog signal to digital information.

In music players that use digital media, which constitutes the majority on the market today, digital to analog converters make it possible to actually hear the music. The music is stored in digital format, which is accomplished by using an analog to digital converter, detailed below. The digital information—a series of ones and zeroes—is take the digital information and convert it back into an analog signal; the voltage that is put through the speakers, producing the sound.

These also play a significant role in VoIP technology. VoIP technology takes analog information—the sound of a speaker’s voice—and samples it and then converts it into digital information. The digital information is transmitted over the line. Before the listener can hear the voice, it is decoded by a DAC, producing the speaker’s voice over the line.

DAC technology is also used in video technology, as well, though less heavily than it was in the past. Today, most monitors have digital inputs, which eliminate the necessity to convert the digital data to analog. Should a monitor have analog inputs, however, a DAC is required to convert the information from one form to the other.

Analog to digital converters, intuitively enough, are used for the reverse of the processes listed above, but are also employed in many other applications. In the case of music, the ADC devices are oftentimes used during the recording process. In order for music to be encoded onto a CD or another digital format, the audio signal has to be sampled and converted to numerical data that can be encoded into the desired format. The ADC provides this capability.

Where ADC devices are concerned, sample rates are vital specs. The sample rate determines how accurately the ADC can represent the analog signal in digital form. The higher the sample rate, the better.

ADC devices can work very fast, and that’s vital for some signal processing applications. Scientific instruments, such as oscilloscopes and microcontrollers commonly employ these devices in their designs. These devices are also used in applications where a signal such as a television broadcast or a radio signal is converted to digital data, such as in the case of TV tuner cards and software defined radio.

ADC technology is also used extensively in scientific instruments of various types. They are used to process signals in some radar systems. They are also used to quantize information recorded as analog signal, such as light levels, temperature, electrical characteristics and other data. This information is read in sensors that produce analog output, which is then converted to digital information that can be read by the operator on a display. These devices commonly include an amplifier for the analog signal.


What Is the Difference Between a Digital-to-Analog Converter and an Analog-to-Digital Converter?

A DAC and an ADC differ in the obvious regard that one converts digital signal to analog and the other analog signal to digital. However, there is a more substantive difference between these two devices in practice.

A digital to analog converter starts with data that is completely and wholly understood. It is represented by a series of 1s and 0s, all its parameters defined. The converter takes that data and converts it into some sort of an analog signal. Because—as long as it is not corrupted—digital data can be copied endlessly without changing that data, a DAC has the advantage of always starting out with a known set of values and simply has to convert them into the analog signal.

By contrast, the work of an ADC is much more difficult. Analog signal can be random. The signal is generally continuous with modulations within it that have to be sampled and converted to digital data. The rate at which the ADC can sample, as well as the resolution of those samples—meaning how subtle the differences between one period of the signal and the next can be read by the ADC—determine the quality of the digital information the ADC produces. The ADC is a complex device that has to take into consideration the need for signal conditioning and other methods of improving the information that it works with, thus allowing it to produce a better digital representation of the analog signals being read.


How Does a Digital to Analog Converter Operate?

A digital to analog signal converter starts out with a binary number, which is an abstract value that could refer to anything. It takes this information and, through the circuitry in the device, converts them to an analog signal that can be put through speakers or another device to achieve the desired result: audio signal, video signal, etc.

To accomplish this, the numbers are converted to impulses. Those impulses are run through a reconstruction filter. This allows the gaps in the data—these exist even at the fastest sampling rates—to be filled in, producing a more accurate result.

Ideally, the variations in the signal produced by the DAC should be very flowing and very natural. This is particularly important in music and video, where poor sampling rates and audio conversion can result in a choppy, low-fidelity sound or inconsistency in the colour gradients and other aspects of video.


How Does an Analog to Digital Converter Operate?

An analog to digital converter is a complex device. The process of converting the signal involves taking small amounts of data—samples—out of an analog signal. These samples are converted to discrete values—the 1s and 0s—that are used to store a digital representation of the analog signal sampled, or to output that data to a display.

For analog signals, resolution is a significant determiner of how well the device represents the signal in digital form.

The inherent challenge for an ADC is the fact that analog signal has, essentially, the potential for an infinite amount of variations in voltage within the signal. The ADC takes the signal recorded in a sample and compares it to a reference voltage. This is used to make the conversion from analog to digital.

An important aspect of ADC devices is quantization error. This is an inevitable problem with ADC technology. Because only portions of the analog signal are actually recorded and converted, there is always some lost signal during the analog to digital conversion process. The highest quality ADC technology loses very little, but there are losses, nonetheless.

Once the ADC has sampled the analog signal, it takes that sample and records it as digital data, adding to it as more signal is sampled and converted to binary numbers.


What Types of Data Converters Exist? How Does Each Type Function and What Is It Used For?


Analog Front End ICs

These are integrated circuits that are designed to be used in specific types of technologies. Their applications include digital cameras, scanners, infrared imaging technology, voice recognition technology and more.


Audio and Video Encoders and Decoders

These are ADC components that take the analog signal produced by microphones, cameras and other devices and convert it into a digital form that can be used by digital technology. It must be decoded, which is the role of the decoder devices in this category.


Audio ADCs

An audio ADC is one of the most common types of converter on the market. These devices take the analog signal from a microphone or other audio equipment and convert it to digital information that can be sensors, recording device and so forth.


Audio DACs

In order to decode information that has been converted from analog audio signal to digital format, a DAC must be used. These are very common DAC devices, used in CD players and any other appliance that converts digitally stored audio information into an analog form.


Audio Decoder ICs

Audio decoders take the digital representation of an audio signal and decode it so it can be converted into audio signal. The IC contains all the circuitry needed for this process.


Audio Encoder ICs

Audio encoder ICs contain all the circuitry required to encode an audio signal into digital data after it is sampled. These are used in many different applications, from converting voices to digital data for voice recognition to providing a way to put audio music data into a digital form.


Capacitance to Digital Converters

Used in instrumentation, these converters take capacitance measurements, which are analog, and convert them into digital data that can be read by the operator. They are used in both consumer-grade and industrial-grad products.


Data Acquisition Systems

Data acquisition systems are designed to measure variables such as sound, light, pressure, voltage, current and so forth. They incorporate the apparatus used to take the measurements, the IC used to do the processing and other elements. The IC is sometimes sold under this name, as well.


Digital Potentiometers

These are used in the same way as their analog cousins. They are used to trim circuits and can interface with computers and other devices.


Energy Measurement ICs

These are integrated circuits that provide the full functionality required to take digital measurements of energy levels. They are differentiated by resolution, conversion rate, pin count and other variables.


General Purpose ADCs

These can convert analog signals from a variety of different sources to digital data that can be sorted and manipulated as needed. They come in many different pin configurations and designs.


General Purpose DACs

These are DACs that can be integrated into many different builds to convert digital information to analog signal. They come in a variety of designs.


Resolver to Digital Converters

Resolvers take information form mechanical devices, such as the position of a shaft, and convert that to digital information. They can also convert data such as velocity and angle.


Sample and Hold Circuits

These can take a variable voltage from an analog signal and hold the value at a given level.


Sample Rate Converters

Digital information is recorded by sampling at a specific rate. These devices can take one sampling rate to be converted to another.


Touch Screen Controllers

These are utilized in both resistive and capacitive screens. They convert the user’s presses and movements on the screen to signals that can be read by the device.


Touch Screen Digitizers

These components are used to take the analog signal from the user’s finger on a touch screen and convert it to digital data that can be interpreted by the device itself.


Video ADCs

These are common components that take analog input from a video source and convert it to digital data. They are similar to audio ADCs, having sample rates and other variable that affect their performance.


Video DACs

These are generally used on monitors and screens that have analog inputs. They take digital video data and convert it to a format usable by the device.


Video Decoder ICs

These are the integrated circuits responsible for decoding digital video data into analog signal.


Video Encoder ICs

These integrated circuits convert take the data gathered from video sources and encode it in digital form, where it can be stored and copied without degrading.


Voltage-to-Frequency & Frequency-to-Voltage Converters

These devices can take a voltage and convert it to a proportional frequency of vice versa. They come in synchronous, asynchronous and non-synchronous varieties.


Resource: /web/c/semiconductors/data-converters/