Physics
Digital to Analog Conversion
Digital to analog conversion is the process of converting digital signals into analog signals. In this process, discrete digital values are transformed into continuous analog waveforms. This conversion is essential for transmitting digital data over analog mediums, such as audio or video signals, and is commonly used in various electronic devices like smartphones, music players, and televisions.
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11 Key excerpts on "Digital to Analog Conversion"
- Steven F. Barrett, Daniel J. Pack(Authors)
- 2022(Publication Date)
- Springer(Publisher)
We do not want the sample to vary during the conversion process. 5.4.3 Digital-to-Analog Conversion Once a signal is acquired to a digital system with the help of the analog-to digital conversion process and has been processed, frequently the processed signal is converted back to another analog signal. A simple example of such a conversion occurs in digital audio processing. Human voice is converted to a digital signal, modified, processed, and converted back to an analog signal for people to hear. The process to convert digital signals to analog signals is completed by a digital-to-analog converter. The most used technique to convert digital signals to analog signals is the summation method shown in Figure 5.9. FIGURE 5.9: A summation method to convert a digital signal into a quantized analog signal. Com- parators are used to clean up incoming signals and the resulting values are multiplied by a scalar multiplier and the results are added to generate the output signal. For the final analog signal, the quantized analog signal should be connected to a low pass filter followed by a transducer interface circuit ANALOG-TO-DIGITAL CONVERSION 81 With the summation method of digital-to-analog conversion, a digital signal, repre- sented by a set of ones and zeros, enters the digital-to-analog converter from the most sig- nificant bit to the least significant bit. For each bit, a comparator checks its logic state, high or low, to produce a clean digital bit, represented by a voltage level. Typically, in a micro- controller context, the voltage level is +5 or 0 V to represent logic one or logic zero, re- spectively. The voltage is then multiplied by a scalar value based on its significant position of the digital signal as shown in Figure 5.9. Once all bits for the signal have been processed, the resulting voltage levels are summed together to produce the final analog voltage value.
eBook - PDFDigital Electronic Circuits
Principles and Practices
- Shuqin Lou, Chunling Yang(Authors)
- 2019(Publication Date)
- De Gruyter(Publisher)
11 Analog-to-digital and digital-to-analog converter 11.1 Introduction With the rapid development of digital technology, digital technology has already been applied to a wide range of areas besides computer system. Such applica-tions include communication systems, radar, navigation and guidance systems, military systems, medical instrumentation, industrial process control, and many others. However, digital circuits and digital systems deal with digital quantity. From physics point of view, a digital quantity is the one having a discrete set of values. Most things that can be measured quantitatively in nature with analog form. In order to process these analog quantities with digital technique, it is necessary to convert the analog quantity to a digital one. The device that converts an analog signal to a digital signal is called the analog-to-digital converter (ADC). Moreover, most electronic instruments are driven by analog signals and thus the processed digital quantity must be converted back to analog signal to drive the electronic equipment. The circuit that converts the digital signal to an analog signal is called the digital-to-analog converter (DAC). This chapter first introduces the basic concepts and then the operating princi-ples of DAC and ADC. Several typical integration DAC and ADC chips and their applications are also covered. The objectives of this chapter are to – Explain how analog signals are converted to digital forms – Describe the sample process – State the purpose of digital-to-analog conversion – Explain the operating process of several types of DACs – State the purpose of analog-to-digital conversion – Explain the operating process of several types of ADCs 11.2 Digital-to-Analog Converter (DAC) In electronics, a digital-to-analog converter (DAC, D/A, or D-to-A) is a circuit that converts a digital signal into an analog signal. DAC is an important part of a digital processing system.
eBook - ePubDigital Electronic Circuits
Principles and Practices
- Shuqin Lou, Chunling Yang(Authors)
- 2019(Publication Date)
- De Gruyter(Publisher)
11 Analog-to-digital and digital-to-analog converter11.1 Introduction
With the rapid development of digital technology, digital technology has already been applied to a wide range of areas besides computer system. Such applications include communication systems, radar, navigation and guidance systems, military systems, medical instrumentation, industrial process control, and many others. However, digital circuits and digital systems deal with digital quantity. From physics point of view, a digital quantity is the one having a discrete set of values. Most things that can be measured quantitatively in nature with analog form. In order to process these analog quantities with digital technique, it is necessary to convert the analog quantity to a digital one. The device that converts an analog signal to a digital signal is called the analog-to-digital converter (ADC). Moreover, most electronic instruments are driven by analog signals and thus the processed digital quantity must be converted back to analog signal to drive the electronic equipment. The circuit that converts the digital signal to an analog signal is called the digital-to-analog converter (DAC). This chapter first introduces the basic concepts and then the operating principles of DAC and ADC. Several typical integration DAC and ADC chips and their applications are also covered.The objectives of this chapter are to- – Explain how analog signals are converted to digital forms
- – Describe the sample process
- – State the purpose of digital-to-analog conversion
- – Explain the operating process of several types of DACs
- – State the purpose of analog-to-digital conversion
- – Explain the operating process of several types of ADCs
11.2 Digital-to-Analog Converter (DAC)
In electronics, a digital-to-analog converter (DAC, D/A, or D-to-A) is a circuit that converts a digital signal into an analog signal. DAC is an important part of a digital processing system. After the digital data are processed, they need to be converted back to analog form. In fact, there are several types of DACs. This section mainly introduces two types of DACs: binary-weighted-input DAC and the R /2R
eBook - PDF- Ian Sinclair, John Dunton(Authors)
- 2013(Publication Date)
- Newnes(Publisher)
Digital -Analogue Conversions 251 Analogue-to-digital conversion CHAPTER 9 DIGITAL -ANALOGUE CONVERSIONS So much signal processing now is digital rather than analogue, and since the display of information is by now much more oriented to digital rather than to analogue methods, the conversion between digital and analogue signals has assumed considerable importance. All conversion from analogue to digital form is based on sampling a waveform and converting the amplitude of each sample into digital signals. The type of digital signal is normally a binary number whose size is proportional to the amplitude of the analogue signal, and the frequency of analogue signal that can be handled depends critically on the rate at which conversion can be achieved. Conversion in the opposite direction has been achieved in the past by methods that used the binary codes of the digital signal to generate analogue voltages which were summed but, as will be explained, this method is often inadequate for precise conversions and has been replaced by other systems, some of which are not quite so new as might be thought at first. A n a l o g u e -t o -d i g i t a l conversion The conversion of analogue signals into digital form (strictly speaking, into pulse-code modulated digital form) is the essential first step in any system that will use digital methods for counting, display or logic actions. It is often necessary to distinguish between conversion and modulation in this context. Conversion means the processing of an analogue signal into a set of digital signals, and modulation means the change from the original digital signal into a type of digital signal that can be stored or transmitted by an error-free method. The two are very often closely bound up with each other because many forms of conversion are also forms of modulation.
eBook - PDF- Ian R. Sinclair(Author)
- 2016(Publication Date)
- Newnes(Publisher)
Chapter 8 Digital-analogue Conversions So much signal processing now is digital rather than analogue, and since the display of information is by now much more oriented to digital rather than to analogue methods, the conversion between digital and analogue signals has assumed considerable importance. All conversion from analogue to digital form is based on sampling a waveform and converting the amplitude of each sample into digital signals. The type of digital signal is normally a binary number whose size is proportional to the amplitude of the analogue signal, and the frequency of analogue signal that can be handled depends critically on the rate at which conversion can be achieved. Conversion in the opposite direction has been achieved in the past by methods that used the binary codes of the digital signal to generate analogue voltages which were summed but, as will be ex-plained, this method is often inadequate for precise conversions and has been replaced by other systems, some of which are not quite so new as might be thought at first. Analogue-to-digital conversion The conversion of analogue signals into digital form is the essential first step in any system that will use digital methods for counting, display or logic actions. It is often necessary to distinguish between conversion and modulation in this context. Conversion means the processing of an analogue signal into a set of digital signals, and modulation means the change from the original digital signal into a type of digital signal that can be stored or transmitted by an error-free method. The two are very often closely bound up with each other because many forms of conversion are 240 Digital-analogue Conversions 241 also forms of modulation. In general, if digital signals are to be transmitted over parallel lines only conversion is needed, but if a serial line is to be used, modulation may be necessary in addition to conversion.
eBook - PDF- E. J. Wightman(Author)
- 2017(Publication Date)
- Butterworth-Heinemann(Publisher)
CHAPTER 9 Analogue-To-Digital Conversion 9.1 Introduction Analogue-to-digital conversion is probably one of the most im-portant processes in any data acquisition system. It forms a key link between physical variables that are essentially analogue by nature, and the alpha numeric output of the system by which form the quantitative values of the process are expressed. Although analogue-to-digital conversion usually describes the conversion of voltages to digital form, it may also refer to the analogue frequency-to-digital conversion process in which a fre-quency proportional to some input parameter is first obtained, such as a shaft rotation. Digital conversion is obtained in such instances by counting pulses for a fixed time interval to obtain a numerical value corresponding to the time integral of input frequency. Certain forms of digital voltmeter depend for their operation on a voltage-to-frequency conversion process. Probably the simplest example of an instrument combining analogue and analogue-to-digital converted display is the car speedometer. The pointer of the instrument takes up an angular position proportional to speed (analogue) and the driver then interprets the appropriate numerical value of speed from the speedometer scale using his eyes to carry out the analogue-to-digital conversion. In addition to obtaining a measure of the instantaneous speed from the pointer display, the distance travelled is indicated on a separate numerical indicator comprising a number of rotating drums each containing the figures 0 to 9. The counters are driven by gearing from the input to the speedo-meter and indicate the distance travelled by totalling the increments 198 ANALOGUE-TO-DIGITAL CONVERSION 199 of distance represented by each rotation of the input drive shaft. It is of interest to note that by stopping the counter at hourly intervals the average speed is indicated numerically in miles per hour.
eBook - ePub- Karl Stephan(Author)
- 2015(Publication Date)
- Wiley(Publisher)
The second major application of electricity to come along was the telephone, which was developed in the 1870s. The sound waves produced by the human voice are continuous variations in air pressure, which were most conveniently translated into continuous variations in voltage by a diaphragm-operated device called a transmitter. A similar device at the receiving end translated the voltage variations back into air-pressure variations to be heard by the ear. We would term the early telephone a primarily analog system, though it soon acquired digital features such as pulse-actuated automatic dialing.As a matter of statistics, the vast majority of electronic signals today are in digital form, meaning that their interpretation involves the ones and zeroes of digital technology. This is mainly because digital signal processing and related digital technologies are vastly more powerful, flexible, and better performing than their analog-signal-processing counterparts, if such counterparts exist at all. Many routine digital processes today could not be performed at all with analog-only systems, no matter how elaborate or expensive.However, many signals of interest exist in analog form—light waves, sound waves, motions of objects, positions of obstacles on a road, and so on. For digital processing to occur, all these analog signals must be transformed into a form that is easily dealt with by digital systems. And at the other end of the process, digital information and commands must often be converted back into an analog quantity or signal. So as long as there are real-world inputs and outputs that are not digital, there will be a need to convert between the analog and the digital domains. The conversion process is the subject of this chapter.We will now turn to more specific definitions and discussions of the two main ways one can represent information in electronics.8.2 ANALOG AND DIGITAL SIGNALS
8.2.1 Analog Signals and Measurements
An analog signal is a form of electrical energy (voltage, current, or electromagnetic power) for which there is (ideally) a linear relationship between the electrical quantity and the value that the signal represents. As an example, in the case of a telephone or microphone signal as discussed in Chapter 6 , there is a direct proportion between the instantaneous sound pressure change p (in pascals) at the microphone and the microphone’s output voltage v
eBook - PDFMicrochip AVR® Microcontroller Primer
Programming and Interfacing, Third Edition
- Steven F. Barrett, Daniel J. Pack(Authors)
- 2022(Publication Date)
- Springer(Publisher)
The same analysis can be performed as we move spatially from the top to the bottom of the image. Analog signals are those whose physical variable values change continuously over their independent variable. Most physical variables, your speech characteristics, movement of stars, 4.2. BACKGROUND THEORY 101 Figure 4.2: A photo of a walking robot. and the music you hear at a concert are all examples of analog signals. Digital signals, on the other hand, have their physical variables defined only for discrete instances over their indepen- dent variables. Although it may look continuous to human eyes, the photo example shown in Figure 4.2 is a discrete signal because pixels (picture elements) that make up a camera image cannot capture all space within the camera frame. The image is only a finite composition of discrete intensity values seen by a discrete number of pixels. Digital signals are important because all signals represented in digital systems, computers, and microcontrollers are in digital forms. The important task is how to faithfully represent analog signals using digital signals. For example, human voices must be converted to corresponding digital signals before they can be routed by digital switching circuits in telephone communication systems. Similarly, voice commands to robots must be converted to a digital form before robots can process the command. 102 4. ANALOG-TO-DIGITAL CONVERSION As shown in the previous examples, we live in an analog world; that is, physical variables are analog signals. It is precisely this reason why the ADC is so very important in any digital systems that interact with an analog environment. 4.2.2 SAMPLING, QUANTIZATION, AND ENCODING In this subsection, three important processes associated with the ADC are presented, starting with the subject of sampling. Imagine yourself as a photographer in an Olympic diving stadium.
eBook - PDF- Paul Regtien, F. van der Heijden, M. J. Korsten, W Otthius(Authors)
- 2004(Publication Date)
- Butterworth-Heinemann(Publisher)
Chapter 6 Analogue to Digital and Digital to Analogue Conversion An analogue signal is not suitable for processing by a digital computer. Only after conversion into a digital signal, can it be handled by the computer. Con- versely, many actuators and other Output devices require analogue signals, hence the digital signals from a computer have to be converted into an analogue format. Analogue-to-digital converters (AD-converters or ADC's) and digital-to-analogue converters (DA-converters or DAC's) are available as modules or integrated cir- cuits. In Chapter 5 digital signals, binary codes and some digital processing elements have been introduced. This chapter starts with an overview of the main causes of conversion errors. The remaining sections are devoted to particular types of converters and their major characteristics. 6.1. Conversion errors In this section we discuss the main errors occurring in the conversion from the analogue to the digital signal domain. These errors include the quantization and sampling errors (which are independent of the converter type) and some converter- specific errors, due to shortcomings of the electronic components of the converter. 6.1.1. Quantization noise Figure 6.1 represents the transfer characteristic of an AD converter. The range of the converter is set by the reference voltage Vre f. Usually, the range is from 0 to Vref, but some converters allow a user-specific range setting, for instance from _! 2 Vref to + 1 Vref An ideal converter performs a perfect rounding off to the nearest quantization level. Obviously, the maximum error is 1LSB or - 89 LSB. For a fixed input signal and range the quantization error decreases with an increasing number of bits n. It is possible to express the quantization error in terms of noise power or in rms value. Suppose the intervals between two successive levels are all the same and equal to q (uniform quantization, see Chapter 3).
eBook - PDF- Jocelyn O. Padallan(Author)
- 2019(Publication Date)
- Arcler Press(Publisher)
There are four important conversion techniques which include digital to digital, digital to analog, analog to digital and analog-to-analog. The same are discussed in detail here. In each technique of conversion, there are many subtypes and all subtypes are explained in a lucid manner. Information about analog and digital data has also been provided in the chapter. In this section, modes of transmission such as parallel or serial modes are discussed along with their applications and advantages. 4.1. INTRODUCTION This chapter is about digital and analog transmission but before that what does we mean by data transmission is an important thing. The process of sending digital or analog data over a medium of communication to one or more computing network communication or electronic devices are called data transmission. Figure 4.1: Analog signal ( Source: https://learn.sparkfun.com/tutorials/analog-vs-digital/analog-signals). It enables the transfer and communication of devices in a point-to-point, point-to-multipoint and multipoint-to-multipoint environment. The transmission of data can be analog and digital but it is mainly concerned with sending and receiving digital data. So, it is popularly known as digital transmission or digital communication. Digital and Analog Transmission 85 Figure 4.2: Transmission ( Source: https://upload.wikimedia.org/wikipedia/en/ thumb/4/4a/Baud.svg/1280px-Baud.svg.png). The transmission of data is done with the help of a device or piece of equipment, like computer, which aims to send a data object or file to one or multiple recipient devices like a server or a computer. The origin of digital data is the source device from which it originates in the form of discrete signals or digital stream of bits (Figure 4.2). From these sources the streams of data or the signals are positioned over the medium of communication which can be a physical copper wires, wireless carriers and optical fiber and carry forward to the destination or the receiver.
eBook - ePubNonlinear Electronics 2
Flip-Flops, ADC, DAC and PLL
- Brahim Haraoubia(Author)
- 2019(Publication Date)
- ISTE Press - Elsevier(Publisher)
2Analog-to-Digital and Digital-to-Analog Converters
Abstract
In general, the role of an analog-to-digital converter (ADC) is to transform an analog signal into a series of numeric codes that represent the amplitudes of the samples of the analog signal. Therefore, before proceeding with the conversion operation, first, a sampling of the analog signal should be performed. Sampling is achieved in the more general case at regular intervals. An analog-to-digital converter is schematically presentedKeywords
Analog signal; Analog-to-digital converter; Digital signal; Digital-to-analog converter; Dual-ramp converters; Field-effect transistor; Shannon’s theorem; Single-ramp converters; Voltage–frequency converters; Zener diode2.1 General information
2.1.1 Analog-to-digital converters
In general, the role of an analog-to-digital converter (ADC) is to transform an analog signal into a series of numeric codes that represent the amplitudes of the samples of the analog signal. Therefore, before proceeding with the conversion operation, first, a sampling of the analog signal should be performed. Sampling is achieved in the more general case at regular intervals. An analog-to-digital converter is schematically presented in Figure 2.1 .The various quantities involved at the level of the analog-to-digital converter are summarized as follows:Figure 2.1 Principle of an analog-to-digital converter- Ean : an analog sample to be converted;
- Eref : a reference voltage. This voltage must necessarily be very accurate and have a very high stability;
- H: a system command clock. It must be very stable;
- SC: the starting command of the conversion “Start Conversion”;
- CC: the conversion duration control “Control Conversion”.
The analog-to-digital converter must send a signal that indicates its state. For example, this signal is in high state for the duration of the whole analog conversion. Sometimes, this signal or control point that is found at the converter level itself is called “STATE” or “STATUS”
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