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Digital to Analog Converter ( DAC )


Digital to Analog Converter   (DAC)


DAC stand for Digital to Analog Converter . It is a system that converts a digital signal into an analog signal. Example, When you hear digital recordings, you’re actually listening to an analog signal that was converted from digital by a DAC. 
              DACs are commonly used in music players to convert digital data streams into analog audio signals. They are also used in televisions and mobile phones to convert digital video data into analog video signals which connect to the screen drivers to display monochrome or color images.
            Any time a signal is converted from one format to another, there is a potential loss of quality. Therefore, it is important to have a high-quality DAC whether you are converting audio or video signals.


Applications

1.     Audio :- The most common use for a DAC is to convert digital audio to an analog signal. This conversion typically takes place in the sound card, which has a built-in DAC. The digital signal, which is basically a stream of ones and zeros, is transformed into an analog signal that might take the form of an electrical charge. This electrical charge is recognized by most speaker inputs and therefore can be output to a speaker system. The audio DAC is a low-frequency, high-resolution type.

2.     Video :- DACs are also used for converting video signals. Previously, most video displays, such as TVs and computer monitors used analog inputs. But now from the last couple of years, digital displays with DVI and HDMI connections have become common. Therefore, in order for a computer to output to an analog display, the digital video signal must be converted to an analog signal. This is why all video cards with an analog output (such as a VGA connection) also include a DAC. The video DAC is a high-frequency low- to medium-resolution type.

3.  Display Electronics :- The graphic controller will typically use a lookup table to generate data signals sent to a video DAC for analog outputs such as Red, Green, Blue (RGB) signals to drive a display.
4.     Motor Control :- Many motor controls require voltage control signals, and a DAC is ideal for this application which may be driven by a processor or controller.
5.     Software Radio :- A DAC is used with a Digital Signal Processor (DSP) to convert a signal into analog for transmission in the mixer circuit, and then to the radio’s power amplifier and transmitter.
6. Data Distribution System :- Many industrial and factory lines require multiple programmable voltage sources, and this can be generated by a bank of DACs that are multiplexed. The use of a DAC allows the dynamic change of voltages during operation of a system.

Types of DAC

1.     Pulse-width modulator
2.     Oversampling DAC
3.     Binary-weighted DAC
4.     R-2R ladder DAC
5.     Cyclic DAC
6.     Thermometer-coded DAC
7.     Hybrid DAC

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