D/A converter

Digital-to-analog converters, say again D/A converter, abbreviation DAC, it is the digital quantity change into analog devices. D/A converter basically composed by four parts, namely power resistance network, operational amplifiers, benchmark power and analog switches. ADC generally with digital-to-analog converters, ADC namely A/D converter, abbreviation ADC, it is the continuous analog signals into discrete digital signal devices.

Digital-to-analog converters analytic principle

A binary digital quantity forms of discrete signal converting to standard amount (or A reference amount of benchmark analog quantities of converter, abbreviation DAC or D/A converter.

The most common way digital-to-analog converters

The most common digital-to-analog converters is parallel to the digital quantity converts binary dc voltage or dc current, it is usually used as process control computer system output channel, and actuators are linked together, the realization of the production process of automatic control. Digital-to-analog converters circuit are used for using a feedback technology adc design.

Digital-to-analog converters conversion ways

Parallel digital-to-analog

Analog-to-digital conversion has two transformation way: parallel analog-to-digital conversion and the serial analog-to-digital conversion. Figure 1 is typical of parallel digital-to-analog converters structure. Dotted line box of digital operation switch and resistor network is the basic components. Figure device through an analogue reference voltage and a resistor trapezoid network produces on the reference quantity as the benchmark scores of right or right value current voltage, Using digital input variables control by a group of switch to decide which some current or voltage sum up form output. The so-called "rights", is the binary number of each represents the value. For example the three binary number "111", right 1 bit "rights" is 20/23 = 1/8; Second place is 21/23 = 1/4, The third is 22/23 = 1/2. Figures more ordinal analogy. Figure 2 for the three digital-to-analog converters the basic circuit, a reference voltage VREF in R1, R2, R3 produced in binary right currents, current through the switch. When the bit values is "0", and to connect, When the bit values is "1", and output summarizations busbar is connected. A few road current generated by the feedback resistance sum Rf output voltage. Voltage polarity and reference quantity instead. Input terminal of the digital quantity every change 1, only cause output relative amounts change 1/23 = 1/8, this value is called digital-to-analog converters resolution. Figures more resolution is taller, conversion of precision is higher also. Industrial automatic control system adopts the digital-to-analog converters are mostly 10, 12, convert the precision of 0.5 ~ 0.1%.

Serial digital-to-analog

Serial analog-to-digital conversion is the digital quantity convert pulse sequence number, a pulse equivalent to the digital quantity of a unit, then each pulse into unit analog quantities, and will all the units analogue addition, get with the digital quantity proportional to the analog output, so as to realize the digital quantity and analogue conversion.

Along with the digital technology, particularly the rapid development of computer technology and popularization, in modern control, communication and testing etc, in order to improve the performance of the system indexes, the signal processing is widely adopted digital computer technology. Due to the system of the actual object tend to be some analog quantities (such as temperature, pressure, displacement, images, etc), to make the computer or digital instrument can identify, handling these signals, must first will these analog signals converts digital signal, And through computer analysis, after processing output the digital quantity also often need to convert to the corresponding simulation signal can be accepted for actuators. So, you need a can in analog signals and digital signal serve as a bridge between the circuit -- modulus and digital-to-analog converters.

Convert an Analog signal into A Digital signal circuit, called ADC (hereinafter referred to as the A/D Converter or ADC, Digital Converter); to Analog to produce stats Converting Digital signals for Analog signal circuit called digital-to-analog converters (hereinafter referred to as D/A Converter or DAC, Digital Converter); to Analog to produce stats A/D converter and D/A converter computer system has become an indispensable interface circuit.

To ensure system for handling the accuracy of the results, A/D converter and D/A converter must have enough of conversion precision, If we are to achieve rapid variation signal of real-time control and testing, A/D and D/A converter also requires high converting speed. Convert precision and converting speed is measured A/D converter with D/A is an important technical indicators. With integrated technology development, has been developed and produced many single chip and mixed set molding of A/D converter and D/A, they have more and more advanced technology index. This chapter introduces several common A/D and D/A converter circuit structure, working principle and its application.