7 Differences Between ADC and DAC

By Dominic Cooper on August 17, 2022

There are two types of signals converters namely, an Analog to Digital Converter and a Digital to Analog Converter.

Though the purposes of the two are the same, there are some specific differences between an Analog to Digital Converter, more commonly known as ADC, and a Digital to Analog Converter, more commonly referred to as DAC.

This article consists the major differences between these two signal converters that you will find being used in a lot of different electronic items.

KEY TAKEAWAYS

The 7 Differences Between ADC and DAC

Differences Between ADC and DAC

1. The Concept

The Analog to Digital Converters usually capture mainly unknown signals and convert them into any known representation.

This means that the ADCs typically work on the basis of unknowns at random.

On the other hand, the Digital to Analog Converters take in well understood and fully known inputs and simply generates a corresponding analog value.

Therefore, the DACs work in a more deterministic world.

2. Input and Output

The Analog to Digital converter takes in a continuous physical quantity which is normally voltage and gives out a digital number that signifies the amplitude of the quantity.

On the other hand, in a Digital to Analog Converter, the input is a binary number and the output is a current signal or an analog voltage.

3. Purposes

An Analog to Digital Converter transforms the analog signals transmitted into digital signals.

On the other hand, the Digital to Analog Converter performs the inverse function and transforms digital signals into analog signals.

4. Types

As for the Analog to Digital Converters, you will typically find five major types available in the market such as Successive Approximation or SAR ADC, Delta-Sigma ADC, Dual Slope ADC, Pipelined ADC, and Flash ADC.

On the other hand, as for the Digital to Analog Converters, you will find two major types of it such as Binary Weighted DACs that can be of two further types such as String Resistor DAC and Weighted Resistor DAC, R-2R Binary Ladder DACs, Interleaving DACs or Pipelined DACs.

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5. Mapping Value

The Analog to Digital Converter usually maps the given input voltage between a specific range which may be typically between -10 volts and 10 volts for example, and gives an output value as an integer that the computer can read easily which may range between 0 and 2047 for example.

On the other hand, a Digital to Analog Converter typically maps the given input value which may be an integer between 0 and 2047 for example and gives an output voltage in a particular range which may be between -10 volts and 10 volts for example.

6. Applications

As for the Analog to Digital Converters, there are varied applications of them such as in digital voltmeters, mobile phones, scanners, and voice recorders to name a few.

On the other hand, the different applications of a Digital to Analog Converter include in the modems, video adapters, printers, digital motor control, function generators or oscilloscopes, digital audio and sound equipment.

7. Performance Characteristics

There are different characteristics that are to be taken into consideration to evaluate the performance of the Analog to Digital Converters such as speed, accuracy, resolution, and dynamic range.

On the other hand, the varied performance characteristics of the Digital to Analog Converters are Speed, resolution, dynamic range, glitch impulse area, settling time, SFDR or Spurious Free Dynamic Range, ENOB or Effective Number of Bits, and SNR or Signal to Noise Ratio.

Which is More Important – ADC or DAC?

Ideally, it is quite impossible to say that the Analog to Digital Converter is better and more useful than the Digital to Analog Converter and vice versa.

This is because both these are important for a computer system to work properly and for other systems to help in communicating and other purposes.

However, the ADCs seem to have a miniscule edge over the DACs given the fact that, in the computer world in particular, everything happens in analog form and that should be transformed into digital signals during output.

The working process of the two converters, ADC and the DAC, may be different but the eventual purpose happens to be the same.

The Analog to Digital converters, just as the name indicates, takes in the raw electrical or analog signals and gives out digital signals after converting them into digital information which is displayed on the output devices or is produced as sound.

As for example, microphones usually take in sound energy and convert them into electrical currents.

This current then passes through the computer but this cannot be stored in it as information.

This is where the Analog to Digital Converter comes into play. It takes on the responsibility of altering that current into digital data so that it can be accessed and manipulated by the computer.

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The current from the microphone varies in voltage depending on the audio and when it travels to the Analog to Digital Converter, it typically takes samples of it.

Though most of the ADCs use about 44,100 samples per second, there are a few that may even take in more.

Each of these samples is measured by the ADC depending on the voltage in them and a series of binary digits is assigned to each.

These series of binary digits are then collected in a digital file that can be stored.

This number of digits assigned to each sample matches with the number of output pins in the ADC.

There are several input and output pins in an Analog to Digital Converter that may typically range anywhere from 8, 16, 24, and up to 32 pins.

The number of pins in the ADC is very crucial because the higher the number of pins, the better will be the sound output and the reliability of recorded audio.

On the other hand, the Digital to Analog Converters works in just the opposite way of the ADCs.

They take in digital signals and change them into analog signals.

These signals then travel to the headphones or speaker as an electrical current.

Typically, the Bluetooth speakers and headphones come with the Digital to Analog Converters built in them.

Just like the ADCs, the DACs too have a similar construction wherein there is a specific number of input and output pins that serve the same purpose, which is to enhance the integrity of the audio.

For example, in a 4-bit Digital to Analog Converter with a sample code 1010 passing through it, the input pins are actually with a 1 and pass a current through them to their relevant output pins.

On the other hand, the pins with a 0 will normally not pass any signal through them.

However, in a DAC, the different arrangements of binary digits allow passing different total voltages to the speaker.

This is due to the fact that the resistors in a Digital to Analog Convertor are coupled to the output pins.

Here each of the pins outputs an electricity of 10 volts and each of the resistors halve it.

Therefore, the 1010 sample code in the example above will give a voltage output of 3.125 volts and if it was an 1101 sample code the total output voltage would have been 6.875 volts.

Therefore, both these converters are necessary and that is why you will find the ADCs and DACs are almost omnipresent in the digital world of today. These are used in almost everything such as:

Typically, the purpose of Analog to Digital Converters should not be ignored due to the several benefits that they offer such as:

In general, both of them are heavily dependent on the performance of the clock oscillator or oscillators so that repeatable and most precise sampling process is achieved.

Therefore, in the end, it can be said that the signal processing today is digital and the transition between the analog and digital domains is done with the help of the Analog to Digital Converter and the Digital to Analog Converter.

It is very simple to link a digital circuitry to the sensor devices if these devices are intrinsically digital themselves in the first place.

But, with analog devices, things become much more complicated.

This is because converting a digital signal to an analog signal is much easier than doing the reverse.

Still, at the core of the data acquisition system is an Analog to Digital Converter since most of the systems available today are digital in nature and need discrete digital data, and this cannot be sent through air.

It is true that most of the communication happens through a specific channel through air.

It is therefore more necessary to change any digital signal into analog signals so that it can travel through the air.

Therefore, even if they both do drastically different jobs, one would be useless without the other.

However, it is the needs of the particular application that will determine which among the Digital to Analog Converter and the Analog to Digital Converter is required to ensure an optimal performance and improved functionality of the specific electronic system.

Conclusion

So, now that you know the difference between the Digital to Analog Converters and the Analog to Digital Converters and their significance, as a designer you should not overlook any of them since that will result in system and circuit level hindrances both at the prototype evaluation and in reality.