12
Data Conversion Circuits – D/A
and A/D Converters
Digital-to-analogue (D/A) and analogue-to-digital (A/D) converters constitute an essential link when
digital devices interface with analogue devices, and vice versa. They are important building blocks
of any digital system, including both communication and noncommunication systems, besides having
other applications. A D/A converter is important not only because it is needed at the output of most
digital systems, where it converts a digital signal into an analogue voltage or current so that it can be fed
to a chart recorder, for instance, for measurement purposes, or a servo motor in a control application;
it is also important because it forms an indispensable part of the majority of A/D converter types. An
A/D converter, too, has numerous applications. When it comes to transmitting analogue data, it forms
an essential interface with a digital communication system where the analogue signal to be transmitted
is digitized at the sending end with an A/D converter. It is invariably used in all digital read-out
test and measuring equipment. Whether it is a digital multimeter or a digital storage oscilloscope or
even a pH meter, an A/D converter is an important and essential component of all of them. In this
chapter, we will discuss the operational fundamentals, the major performance specifications, along with
their significance, and different types and applications of digital-to-analogue and analogue-to-digital
converters, in addition to application-relevant information of some of the popular devices. A large
number of solved examples is also included to illustrate the concepts.
12.1 Digital-to-Analogue Converters
A D/A converter takes digital data at its input and converts them into analogue voltage or current that
is proportional to the weighted sum of digital inputs. In the following paragraphs it is briefly explained
Digital Electronics: Principles, Devices and Applications Anil K. Maini
© 2007 John Wiley & Sons, Ltd. ISBN: 978-0-470-03214-5
Data Conversion Circuits – D/A
and A/D Converters
Digital-to-analogue (D/A) and analogue-to-digital (A/D) converters constitute an essential link when
digital devices interface with analogue devices, and vice versa. They are important building blocks
of any digital system, including both communication and noncommunication systems, besides having
other applications. A D/A converter is important not only because it is needed at the output of most
digital systems, where it converts a digital signal into an analogue voltage or current so that it can be fed
to a chart recorder, for instance, for measurement purposes, or a servo motor in a control application;
it is also important because it forms an indispensable part of the majority of A/D converter types. An
A/D converter, too, has numerous applications. When it comes to transmitting analogue data, it forms
an essential interface with a digital communication system where the analogue signal to be transmitted
is digitized at the sending end with an A/D converter. It is invariably used in all digital read-out
test and measuring equipment. Whether it is a digital multimeter or a digital storage oscilloscope or
even a pH meter, an A/D converter is an important and essential component of all of them. In this
chapter, we will discuss the operational fundamentals, the major performance specifications, along with
their significance, and different types and applications of digital-to-analogue and analogue-to-digital
converters, in addition to application-relevant information of some of the popular devices. A large
number of solved examples is also included to illustrate the concepts.
12.1 Digital-to-Analogue Converters
A D/A converter takes digital data at its input and converts them into analogue voltage or current that
is proportional to the weighted sum of digital inputs. In the following paragraphs it is briefly explained
Digital Electronics: Principles, Devices and Applications Anil K. Maini
© 2007 John Wiley & Sons, Ltd. ISBN: 978-0-470-03214-5