How to Choose a Digital to Analog Converter

11/04/2020, hardwarebee

Digital to analog converters or DACs are very commonly and frequently implemented components in electronic gadgets and devices. As suggested by the name, a digital to analog converter allows you to change a digital signal into an analog one. Typically, the stuff that you store on your computer or any other tech device is saved in the binary form- a set of 1s and 0s that encode some information.



If you want to turn this digital information into an analog signal such as audio, graphics, or any other form which can be perceived by the senses, then you will need a translator which is a digital to analog converter in most cases. This means that you are using a digital to analog converter even when you try to listen to a song on your computer or mobile phone. They may also be used in combination with analog to digital converters in certain applications.


Types of Digital to Analog Converter


You should familiarize yourself with the types of digital to analog converters available in the market beforehand. Each of the three most commonly used types of DACs have their own pros and cons which makes them best suited for certain applications based on their individual characteristics.


Digital to Analog Converter using the Summing Amplifier


A binary weighted input digital to analog converter is a summing circuit. It adds the inputs that are contributed by the digital bits of incoming data using an inverting summing amplifier. The resistors in the circuit are weighted in a binary format meaning if they receive an input of 1, the switch connects the resistor to the reference voltage whereas an input of 0 connects it to the ground terminal. However, with increasing bits of data, the accuracy of this system becomes rather poor.



R-2R Ladder

In an R-2R digital to analog converter, you have a set of resistors that have repeating values of R and 2R. This kind of an arrangement enables them to produce value matched resistors, which in turn increases the precision of these devices. These converters are usually more precise and are the optimal choice for heavy weight or demanding applications and tasks.



Segmented DACs

Segmented DACs combine the features of multiple architectures to give you the best of both worlds. It uses one kind to deal with the significant bits and the other to handle the least significant bits. Understandably, these DACs tend to be much more expensive than their individual parts.


Before you Start…


Before you start looking at your options, it is important to determine exactly what you want out of the product you are going to invest in. These prerequisites will act as rough guidelines for the minimum requirements or specifications that your ideal digital to analog converter should fulfil. Ask yourself the following questions before you choose the type of digital to analog converter you want for your electronic device:


  • What kind of a digital file will you be using the digital to analog converter to translate? This can be audio, video, or any other format.
  • Do you need the conversion to be fast? Is speed a critical component of the process? Typically, if you are going to be decoding video files, it is better to invest in a speedier converter as you need to convert a large amount of data for a single video file.
  • Or would you rather preserve the resolution and compromise on the speed factor? Higher resolution converters are preferred for audio applications as only a small amount of data must be converted which takes the need for speed out of the picture.
  • How many channels do you need for the output?


These questions will help you determine the specificity in the kind of converter you require and help narrow down your search to a few good options so that your decision making process yields you the most suitable result for your electronic product.



Choosing the Right Digital to Analog Converter


You can use the following parameters to formulate a criteria using which to judge the quality and specifications of a given digital to analog converter. These critical factors include speed, resolution, monotonicity, and the dynamic range of the DAC converter.



Speed refers to the maximum sampling rate of the circuit. This refers to the maximum speed at which the system can run a sample while maintaining the accuracy of the output.



The resolution of a digital to analog converter refers to the number of output levels it can possibly produce. Expressed in the form of bits, the resolution of the converter determines various features of the resulting analog output signal such as the color depth in video files and the audio bit depth in audio applications. The resolution also determines the least significant bit or the LSB which is the smallest increment change that can be produced in the output in response to the input.


Dynamic Range

The dynamic range can be found by calculating the difference between the maximum possible output and the minimum possible output that can be produced by the given conversion system. This measurement is expressed in decibels and is associated with the resolution of the device.



Monotonicity refers to the ability of the converter to ensure that the output is moving in the direction of the input. This means that when the input increases, the output increases as well. Same goes for a decrease in the input signal. There should not be a dip in the output signal before it returns to the correct output.


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