12bit 低功耗DAC 數模轉換器
The MAX5302 combines a low-power, voltage-output,
12-bit digital-to-analog converter (DAC) and a precision
output amplifier in an 8-pin μMAX package. It operates
from a single +5V supply, drawing less than 280μA of
supply current.
This work titled A Digital Phase Locked Loop based Signal and Symbol Recovery
System for Wireless Channel is intended to serve as a document covering funda-
mental concepts and application details related to the design of digital phase locked
loop (DPLL) and its importance in wireless communication. It documents some
of the work done during the last few years covering rudimentary design issues,
complex implementations, and fixing configuration for a range of wireless propa-
gation conditions.
Optical communication technology has been extensively developed over the
last 50 years, since the proposed idea by Kao and Hockham [1]. However, only
during the last 15 years have the concepts of communication foundation, that
is, the modulation and demodulation techniques, been applied. This is pos-
sible due to processing signals using real and imaginary components in the
baseband in the digital domain. The baseband signals can be recovered from
the optical passband region using polarization and phase diversity tech-
niques, as well as technology that was developed in the mid-1980s.
While teaching classes on digital transmission and mobile communications for
undergraduate and graduate students, I was wondering if it would be possible to
write a book capable of giving them some insight about the practical meaning of the
concepts, beyond the mathematics; the same insight that experience and repetitive
contact with the subject are capable to construct; the insight that is capable of build-
ing the bridge between the theory and how the theory manifests itself in practice.
The field of digital communication has evolved rapidly in the past few
decades, with commercial applications proliferating in wireline communi-
cation networks (e.g., digital subscriber loop, cable, fiber optics), wireless
communication (e.g., cell phones and wireless local area networks), and stor-
age media (e.g., compact discs, hard drives). The typical undergraduate and
graduate student is drawn to the field because of these applications, but is
often intimidated by the mathematical background necessary to understand
communication theory.
OSCILLATORS are key building blocks in integrated transceivers. In wired and
wireless communication terminals, the receiver front-end selects, amplifies and
converts the desired high-frequency signal to baseband. At baseband the signal can
then be converted into the digital domain for further data processing and demodula-
tion. The transmitter front-end converts an analog baseband signal to a suitable high-
frequency signal that can be transmitted over the wired or wireless channel.
The third generation (3G) mobile communication system is the next big thing
in the world of mobile telecommunications. The first generation included
analog mobile phones [e.g., Total Access Communications Systems
(TACS), Nordic Mobile Telephone (NMT), and Advanced Mobile Phone
Service (AMPS)], and the second generation (2G) included digital mobile
phones [e.g., global system for mobile communications (GSM), personal
digital cellular (PDC), and digital AMPS (D-AMPS)]. The 3G will bring
digital multimedia handsets with high data transmission rates, capable of
providing much more than basic voice calls.
Multi-carrier modulation? Orthogonal Frequency Division Multi-
plexing (OFDM) particularly? has been successfully applied to
a wide variety of digital communications applications over the past
several years. Although OFDM has been chosen as the physical layer
standard for a diversity of important systems? the theory? algorithms?
and implementation techniques remain subjects of current interest.
This is clear from the high volume of papers appearing in technical
journals and conferences.
In this book, we present the basic pinciples that underlie the analysis and design of digital communication system.The subject of digital communications involves the transmission of information in digital form from a source that generates the information to one or more destinations.
In Helsinki during a visiting lecture, an internationally well-known professor in communica-
tionssaid,‘Inthecommunicationssocietywehavemanagedtoconvertourproposalsandideas
to real products, not like in the control engineering society. They have very nice papers and
strong mathematics but most of the real systems still use the old PID controllers!’. As our
background is mainly in control as well as communications engineering, we know that this
thought is not very accurate. We agree that most of the practical controllers are analog and
digital PID controllers, simply because they are very reliable and able to achieve the required
control goals successfully. Most of the controllers can be explained in terms of PID. The
reasons behind this impressive performance of PID will be explained in Chapter 2.
