-
5 RF Transmitter Measurements Every Engineer Should Know

-
ZigBee Alliance Launches Smart Energy Profile 2.0 For HANs
The ZigBee Alliance
has finalized its Smart Energy Profile 2.0 (SEP2) standard, which is
an application for short-range radios using the ZigBee standard for
wireless networking. It implements all the various features needed
for home energy management.

-
Understanding Signal Analyzer Architectures
Many
engineers who use spectrum
analyzers on a regular basis
might be content to know
that their instruments will
produce a display of “power
versus frequency” with
little idea of what’s going
on inside. Despite this,
understanding the
architecture of these
instruments is important to
maximizing their performance
in practical applications.
An RF signal analyzer must
downconvert signals from RF
to a frequency range that
can be digitized with an
analog-to-digital converter
(ADC) with anywhere from 12
to 16 bits of resolution.
The mixer—and its frequency
translation properties—is at
the heart of the
downconversion process,
though I won’t focus on
mixer theory of operation
here (see “What’s
Inside Your RF Signal
Analyzer?”).
Instead, I want to focus on
two main vector signal
analyzer (VSA)
architectures, exploring
both the theory of how they
downconvert signals to
baseband and the tradeoffs
between them.

-
The Fundamentals of Oscilloscope Triggering
A trigger is
defined as “anything, as an
act or event, which serves
as a stimulus and initiates
or precipitates a reaction
or series of reactions.” The
same definition applies to
an oscilloscope trigger. An
oscilloscope trigger
involves waiting for an
event to occur, triggering
upon occurrence of the
event, and then the
oscilloscope capturing and
displaying the electrical
signaling (data) that
follows the trigger event.
For more complex events,
it’s important that an
oscilloscope incorporate
advanced triggering
capabilities. Overall,
oscilloscope triggers have
become important to the
point where they’re often
the deciding factor when
purchasing an oscilloscope.
Software Trigger

-
Essential Steps For Making High-Quality Electrical Measurements
Accurate measurements
are central to virtually every scientific and engineering
discipline, but measurement science tends to suffer for a couple of
reasons. For one, it musters little attention in the undergraduate
curriculum. Secondly, even for those engineers who received a
thorough grounding in measurement fundamentals as undergraduates,
it’s certainly possible—and forgivable—if they’ve forgotten some of
the details.

-
Understanding Onboard Flash Programming
Firmware often is
preprogrammed into flash memory devices prior to the printed-circuit
board’s (PCB) manufacture to maintain high throughput and avoid
slowing the manufacturing beat rate. Yet there are advantages to
programming the flash memory after it has been soldered to the PCB.
In-circuit test (ICT), the Joint Test Action Group (JTAG) interface,
and external connectors all can be used to program flash devices
without impacting manufacturing beat rates. Image size, existing
manufacturing infrastructure, system capability, and required
programming methods also should be considered in choosing an optimal
preprogramming solution.

-
Software Defined Radio Handbook
SDR (Software-Defined
Radio) has revolutionized electronic systems for a variety of
applications including communications, data acquisition and signal
processing. This handbook shows how DDCs (Digital Downconverters)
and DUCs (Digital Upconverters), the fundamental building blocks of
SDR, can replace legacy analog receiver and transmitter designs
while offering significant benefits in performance, density and
cost. In order to fully appreciate the benefits of SDR, conventional
analog receiver and transmitter systems will be compared to their
digital counterparts, highlighting similarities and differences. The
inner workings of the SDR will be explored with an in-depth
description of the internal structure and the devices used. Finally,
some actual board- and system-level implementations and available
off-the-shelf SDR products and applications based on such products
will be presented.


-
PCBWeb, The Latest PCB Design Tool to Hit the Web
Several
browser-based PCB design
tools have emerged in the
past couple of years, yet
the vast majority of
designers are still using
the same desktop
applications that have
dominated the EDA industry
for decades.Now PCBWeb, a
new design tool from the
founders of Aspen Labs, the
media company behind the
electrical engineering
community EEWeb, is the
latest product to be
introduced into this
competitive space. Their
goal? To provide a
full-featured online circuit
design and manufacturing
solution for professional
engineers.

-
Circuit Generates High-Frequency Sine/Cosine Waves From
Square-Wave Input
Although quite a few
direct digital synthesis (DDS) ICs can generate high-frequency sine
waves, their complexity excludes them from many designs. However,
designers can use simple high-frequency CMOS logic and two
switched-capacitor filters to create a sine/cosine generator. With
newer filters, a 1-MHz output at 1.7 V p-p is possible.
The example circuit uses an MSHFS6 5-V, low-power 12.5:1
switched-capacitor filter with selectable Butterworth, Bessel, or
elliptic filters in the lowpass mode and full-, 1/3-, or 1/6-octave
filters in the bandpass mode. Since the lowpass mode would cause a
3-dB loss of the signal output, the circuit uses the 1/6-octave
bandpass filter, which is selected by tying pins 1 and 3 high on the
MSHFS6 (Fig. 1).

-
Understanding The Internet Of Things
Recent developments in
connectivity technologies have spurred the adoption of
Internet-connected “smart” devices for remote sensing, actuating,
and intelligent monitoring using advanced analytics and real-time
data processing. As the pace and the scale of such solutions
increase rapidly, there will soon be a problem getting these
disparate solutions to work seamlessly together to realize a
large-scale Internet of Things (IoT). Recent developments in
protocols and standardization initiatives for the IoT, particularly
application layer protocols, aim to address these issues.

-
Understanding Wireless Range Calculations
One of the key
calculations in any wireless design is range, the maximum distance
between transmitter and receiver for normal operation. This article
identifies the factors involved in calculating range and shows how
to estimate range to ensure a reliable communications link.
Since dBm is
based on a logarithmic
scale, it is an absolute
power measurement. For every
increase of 3 dBm there is
roughly twice the output
power, and every increase of
10 dBm represents a tenfold
increase in power. 10 dBm
(10 mW) is 10 times more
powerful than 0 dBm (1 mW),
and 20 dBm (100 mW) is 10
times more powerful than 10
dBm.You can convert
between mW and dBm using the
following formulas:
P(dBm) = 10 · log10(P(mW))
P(mW) = 10(P(dBm)/10)
For example, a power of
2.5 mW in dBm is:
dBm = 10log2.5 = 3.979
or about 4 dBm. A dBm
value of 7 dBm in mW of
power is:
P = 107/10 =
100.7 = 5 mW

-
Understanding Lithium Battery Tradeoffs In Mobile Devices
Lithium-ion (Li-ion)
batteries give mobile-device designers choices that affect product
convenience, durability, and style. These choices involve tradeoffs
among several parameters, though (see the table).
Understanding how these factors interact requires some knowledge of
Li-ion construction and chemistry.

-
Fundamentals of Communications Access Technologies: FDMA, TDMA,
CDMA, OFDMA,
AND SDMA
Access methods are
multiplexing techniques that provide communications services to
multiple users in a single-bandwidth wired or wireless medium.
Communications channels, whether they’re wireless spectrum segments
or cable connections, are expensive. Communications services
providers must engage multiple paid users over limited resources to
make a profit. Access methods allow many users to share these
limited channels to provide the economy of scale necessary for a
successful communications business. There are five basic access or
multiplexing methods: frequency division multiple access (FDMA),
time division multiple access (TDMA), code division multiple access
(CDMA), orthogonal frequency division multiple access (OFDMA), and
spatial division multiple access (SDMA).




-
An Introduction to LTE-Advanced: The Real 4G
Long-Term
Evolution (LTE) is being
adopted around the world as
the primary cell-phone
communications service.
Multiple 2G and 3G cellular
radio methods are being
phased out as carriers build
their new LTE networks. It
will be years before this
expansion is complete, and
older radio technologies
like GSM and CDMA will
coexist with LTE for a while
(see “The Evolution Of
LTE,”
www.demo.electronicdesign.com/content/evolution-lte
).LTE is likely the
most complex wireless system
ever developed. It
incorporates features that
could not have been
economically implemented as
recently as a decade ago.
Today, with large-scale ICs,
LTE can be easily
accommodated in basestations
and battery-powered handsets
alike. The complexity is a
function of the advanced
wireless methods used as
well as the many options and
features that can be
implemented.
In the meantime, the next
phase of the LTE standards
as put forth by the Third
Generation Partnership
Project (3GPP) is ready to
be deployed.1
Called LTE-Advanced (LTE-A),
this significant upgrade to
the LTE standard will
provide more speed and
greater reliability. While
LTE-A is still being
developed, some LTE-A
service could begin late in
2013.

-
Raise Your Decibel Awareness In Audio Measurements
In the radio-frequency
(RF) microwave test and measurement world, engineers often deal with
the power measurement unit of dBm instead of wattage (W). However,
when entering the audio measurement arena also need to understand
the unit dBu, which is decibel (dB) relative to 1 mW into 600 Ω.
The dBm unit
is defined as:
if a 600-Ω load results
in 0 dBm. Therefore:
Therefore:
The “u” in
dBu represents the word
“unloaded.” It also implies
that the load is
un-terminated, or the load
impedance is unspecified,
and will likely be high.
Thus, the 0.7746 V rms is an
open circuit source.
-
The Fundamentals Of Short-Range Wireless Technology
Wireless has
become a major feature for
just about every new
electronic product. It adds
flexibility, convenience,
and remote monitoring and
control without expensive
wiring and cabling. The
range of applications is
staggering, from simple toys
to consumer electronic
products to industrial
automation.This great
rush to make everything
wireless has produced a
flood of different wireless
technologies and protocols.
Some were established
primarily for one
application, while others
are more general and have
many uses.

-
How Do Operational Amplifiers Operate?
Though sometimes taken
for granted, designers shouldn’t overlook the intricacies of
voltage- and current-feedback op amps—integral players in the analog
and mixed-signal worlds. Op amps amplify tiny signals from sensors
so analog-to-digital converters (ADCs) can digitize them. They also
make it possible to craft active filters with better characteristics
than filters built of just coils and capacitors. Although an IC op
amp’s circuitry tends to be subtle and complex, its application
principles—at least to a first approximation—are relatively simple.

-
Understanding Trusted Computing From The Ground Up
Why is trust related
to computing such a big deal? Imagine if the data on your computer
is visible to others. Or, what if others have changed the data on
your computer? Trust doesn't only refer to "secrets," it also
encompasses the ability to count on your computer to act the way you
expect it to, without unanticipated crashes and appearance of
viruses becoming part of your computing routine. These issues have
made "trusted computing" the electronics industry's biggest
21st-century buzzwords.

-
Fundamentals Of Crystal Oscillator Design
Appropriately
cut quartz crystals can be
used as high-quality
electromechanical
resonators. Their
piezoelectric properties
(voltage across the crystal
deforms it; deforming the
crystal generates a voltage)
allow them to be the
frequency-determining
element in electronic
circuits. Crystals are
widely used in oscillators,
timebases, and frequency
synthesizers for their high
quality factor (QF);
excellent frequency
stability; tight production
tolerances; and relatively
low cost.This article
covers the primary design
considerations for
fundamental-mode oscillators
using AT-cut crystals. These
include load capacitance;
negative resistance; startup
time; frequency stability
versus temperature;
drive-level dependency;
crystal aging; frequency
error; and spurious modes.
This information is based on
experience from more than a
decade designing ISM-band
(industrial, scientific,
medical) radios. (Topics
relevant in other types of
radio systems, such as
crystal oscillator phase
noise, aren’t limiting
factors in ISM radios and
aren’t covered.)
-
Relate ADC Topologies And Performance To Applications
Don’t believe the
hype. The digital revolution hasn’t conquered everything. We still
need analog technologies to gather data and turn it into ones and
zeroes, and the analog-to-digital converter (ADC) remains the
foundation of that process. Different topologies (or architectures)
are available for particular applications, though, so choose your
ADC wisely (see “The
Real World Versus Your ADC”).

-
The Real World Versus Your ADC
Sensors that measure
real-world variables seldom have output signals that can be directly
connected to a data converter in a system. Typically, there are
requirements to amplify, filter, shift offset, and perform other
conditioning functions. Various device families perform these analog
signal processing functions, each with unique strengths and
application requirements.

-
Microcontrollers Tackle Networking Chores
Developers have a
range of wired and wireless mechanisms to connect microcontrollers
to their peers (Table
1). On-chip peripherals often dictate the options, but many of
the interfaces are accessible via off-chip peripherals. External
line drivers and support chips are frequently required as well.

An I2C
network uses two control lines and is typically implemented using
open drain drivers. There is a range of I2C protocols
based around 7-bit and 10-bit device addressing.

-
How To Create And Program USB Devices
The Universal Serial
Bus (USB) standard has been with us for many years, but making USB
devices is still a daunting task. The USB specification comprises
thousands of pages spread over dozens of documents, and although
good books have been written on the subject, they are rarely
shorter. In addition, the application programming interface (API)
offered for programming USB devices is often complex and intricate.
This article describes how to program your own software-based USB
devices. It is not limited to standard class devices, but also
presents a way to implement any device, whether it complies with a
standard class or not.


-
Understanding MPEG Audio Codecs From mp3 To xHE-AAC
-
Understanding HTML5
-
Get More Out Of Your Digital Oscilloscope
-
The Fundamentals Of Spectrum Analysis
The analysis of
electrical signals, otherwise known as signal analysis, is a
fundamental challenge for virtually all electronic design engineers
and scientists. While it provides valuable insight into a signal’s
properties, signal analysis is only as good as the instrument with
which it is performed. Spectrum analyzers and vector signal
analyzers are two instruments commonly employed to analyze
electrical signals. This tutorial covers the basics of how to make
the best use of these instruments.

-
Understanding Amplifier Operating "Classes"
“Class” is in session.
This discussion of electronic amplifier circuits offers an overview
of the characteristics that define commonly used class designations.
The class designations described are A, B, AB, C, D, E, F, G, and H.
-
The Fundamentals Of Flash Memory Storage
-
Back to Basics: Impedance Matching (Part 1)
The term
“impedance matching” is
rather straightforward. It’s
simply defined as the
process of making one
impedance look like another.
Frequently, it becomes
necessary to match a load
impedance to the source or
internal impedance of a
driving source.A wide
variety of components and
circuits can be used for
impedance matching. This
series summarizes the most
common impedance-matching
techniques.

Fig 1. Maximum power is transferred from a source to
a load when the load resistance equals the internal resistance of
the source.

Fig 2. Varying
the load resistance on a source shows that maximum power to the load
is achieved by matching load and source impedances. At this time,
efficiency is 50%.
-
Back to Basics: Impedance Matching (Part 2)
During impedance
matching, a specific electronic load (RL) is made to
match a generator output impedance (Rg) for maximum power
transfer. The need arises in virtually all electronic circuits,
especially in RF circuit design.

-
Back to Basics: Impedance Matching (Part 3)
The L-network is a
real workhorse impedance-matching circuit (see “Back
to Basics: Impedance Matching (Part 2)” ). While it fits
many applications, a more complex circuit will provide better
performance or better meet desired specifications in some instances.
The T-networks and π-networks described here will often provide the
needed improvement while still matching the load to the source.

-
Understanding Noise Terms In Electronic Circuits
-
Understand Signal Analysis In The Time, Frequency, And Modulation
Domains
Modern
oscilloscopes capture, view,
measure, and analyze complex
RF signals in the time,
frequency, and modulation
domains. Time-domain
analysis, the original
oscilloscope function,
allows users to see the
signal’s modulation
envelope. It also enables
measurement of
signal-transition times,
overshoot, and other
time-related
characteristics.The
frequency-domain view shows
the signal’s spectral
content, the power
distribution as a function
of frequency. The
modulation-domain view
allows us to demodulate the
signal and view the
modulation data. This
multi-domain analysis
capability reduces the
number of test instruments
required to completely
characterize signals and
provides a simultaneous view
of all domains.
We will look at a couple
of examples of signals that
benefit from this
multi-domain analysis and
show a comprehensive view of
the three domains.

-
Fundamentals Of Low-Power Design
In the realm
of design, the quest for low
power continues ad infinitum
as a primary goal. Yet
low-power requirements place
significant additional
constraints on designs,
constraints that ordinarily
would be secondary or
non-existent. Often, a
simple oversight in the
firmware executing on a part
can substantially reduce
battery life.When on this
quest, designers must
ask—before writing any code,
selecting components, or
creating schematics—what
“low power” means. Almost
always, the answer is that
it depends. For instance, it
depends on the application,
the typical use case, and a
whole slew of tradeoffs
involving cost, performance,
size, and other factors.

-
Understanding Modern Digital Modulation Techniques
Fundamental to all wireless
communications is
modulation, the process of
impressing the data to be
transmitted on the radio
carrier. Most wireless
transmissions today are
digital, and with the
limited spectrum available,
the type of modulation is
more critical than it has
ever been.The main goal
of modulation today is to
squeeze as much data into
the least amount of spectrum
possible. That objective,
known as spectral
efficiency, measures how
quickly data can be
transmitted in an assigned
bandwidth. The unit of
measurement is bits per
second per Hz (b/s/Hz).
Multiple techniques have
emerged to achieve and
improve spectral efficiency.
Table of Contents
References


-
Use Li-Ion Batteries In Your Next Mobile Computer
Lithium-ion
(Li-ion) cells come in three
basic form factors:
cylindrical, prismatic
(rectangular brick shape),
and flat lithium-polymer (LiPo)
cells. The most commonly
used Li-ion cell is the
cylindrical 18650 cell (Fig.
1). Several million
cells per month are
manufactured, and they’re
used in most notebook
computer applications.The
18650 offers the lowest cost
per watt hour. The “18”
refers to the cell diameter
in millimeters, and the
“650” means it’s 65 mm long.
Li-ion cylindrical (and
prismatic) material layers
are rolled like a jelly
roll. Li-ion cylindrical
(and prismatic) cells are
packaged in metal cans.
Typical capacities of an
18650 cell range from 2.2 to
3.0 Ahrs.
Prismatic or brick-shaped
cells are often
cost-effective and available
in myriad sizes. They also
come in a variety of heights
ranging from about 4 mm to
about 12 mm. The most common
size is the 50-mm length and
34-mm width footprint.
Li-ion prismatic
batteries with a thin
layered polymer can be
housed in a metal can (Fig.
2). Note that the
prismatic cell has a
pressure vent with the
terminals on the metal can.
The positive and negative
terminals on the polymer
cell are tabs protruding
from the cell. The typical
capacity of a prismatic cell
ranges from 1 Ahr to 3 Ahrs.
-
Mixology 101: Mixers And Modulators In High-Speed Communications
In high-speed
wireless communications
systems, signals must be
translated in frequency by
up-conversion or
down-conversion for signal
propagation and processing.
Traditionally known as
mixing, this frequency
conversion is fundamental to
both receive and transmit
chains.
Mixers and modulators,
then, are the basic building
blocks for radio-frequency (RF)
systems. As wireless
communications standards
continue to evolve, it is
essential to review the
characteristics of these
building blocks and to
understand how mixers impact
the overall system
performance.
In any radio design,
mixers and modulators allow
frequency translation and
enable communication. They
establish the basic
specifications for the
entire signal chain. And,
they see the highest power
in the receive chain,
up-convert signals from the
digital-to-analog converter
(DAC) in the transmit path,
and enable digital
pre-distortion (DPD)
systems, impacting the
performance of the complete
communication system.
So how does the basic
mixer work, which
specifications are important
to consider, and what
options of mixers and
modulators are available
today to improve and
simplify system design?




-
Take Time For A Clock-Chip Update
In choosing clock
chips for high-performance data converters, the most critical
datasheet characteristic is jitter, which translates to
phase noise in the frequency domain (Fig. 1). You can
look at the jitter as uncertainty in the placement of the data
conversion. But from an analytical standpoint, it may be useful to
look at that phase noise as a limitation on signal-to-noise ratio (SNR).
Really high-performance, high-speed converters require clocks with
RMS jitter below 200 fs.

-
The
ABCs Of ADCs
-
Rechargeable-Battery Power Management Demands Multiple ICs
-
Can Home Networking Find A Happy Medium?
-
Batteries 101: From Nickel To Lithium And Beyond
Virtually all
battery-based power-management designs depend on the associated
battery, so design starts by picking the specific battery type. The
battery may be the non-rechargeable primary type or the rechargeable
secondary type. The most widely used rechargeable battery-based
systems may employ nickel-cadmium (NiCd), nickel-metal-hydride (NiMH),
lithium-ion (Li-ion), or Li-ion polymer, though silver-zinc
batteries are now emerging.
-
Modern DSP Chips Serve Up Variations On A Theme
-
Welcome To Antennas 101
Antennas are
much more than simple
devices connected to every
radio. They’re the
transducers that convert the
voltage from a transmitter
into a radio signal. And
they pick radio signals out
of the air and convert them
into a voltage for recovery
in a receiver.Typically
taken for granted and left
for the last minute in a
design, antennas are
nonetheless critical for
establishing and maintaining
a reliable radio connection.
They may look complex and
enigmatic to most engineers,
especially EEs working with
wireless applications for
the first time—not to
mention that they come in a
seemingly infinite variety
of sizes and shapes.
However, a brief review of
the essentials can help
allay any design worries.




-
Antennas 102: More Questions And Answers
-
Without Thermal Analysis, You Might Get Burned
-
DDS Basics
-
DDS vs/ Si570
... Hans Summer, G0UPL ...
http://www.hanssummers.com/ddssi570.html
The Si570 is a
relatively new device made by
Silicon Labs. It's a very small device
containing a crystal reference oscillator, digital Phase Locked Loop
(PLL), and I2C interface so it can be programmed for any frequency
between 10MHz and 945MHz (selected frequencies to 1.4GHz). Direct
Digital Synthesis (DDS) chips such as those from the market leader
Analog Devices have been around for
longer. They are very different kinds of parts, even though they are
both oscillators. Accordingly the best choice depends heavily on the
application. These are my opinions about the relative advantages and
disadvantages which may be important factors for your decision.

So after all that [discussion by
category], here's my summary of my opinion on the
various criteria by which to judge these two kinds
of oscillator. Bear in mind that every application
is different! In some applications, some of these
criteria don't matter to you at all, or the decision
of what is better will be clear (and opposite to my
conclusion). In others, you are faced with the usual
decisions about trade-offs. Performance and
complexity; features and cost; etc. But I'll
generalise and operate in typically bi-polar manner
and give my overall winner in every category
regardless, and leave the judging of your
applications to you. |
Category |
Winner |
Ease of construction |
Si570 |
Output waveform |
DDS |
Frequency range |
Si570 |
Frequency stability/accuracy |
DDS |
Frequency agility |
DDS |
Programming interface |
DDS |
Performance: Spurs |
Si570 |
Performance: Phase noise |
DDS |
Power Consumption |
Si570 |
Cost |
Si570 |
Other features |
DDS |
Overall Complexity |
Si570 |
-
Back To Amp Camp
-
Temperature Sensors Are Hot In Circuit Design
-
Stop The Waste In Your Battery-Charger Conversion
-
Make Your Next Design As Solid As A Rock
-
Secure That Microcontroller
Cool Product of the Month
...
Ultimate2 QRSS Kit,
by Hans Summers, G0UPL
The ultimate QRSS Transmitter
Kit is a new version of the original
Ultimate QRSS kit. This
new version comes with a pre-assembled AD9850 DDS module, and
plug-in low pass filter modules
which are also available separately for any band. The kit can transmit on
any frequency from audio (500Hz) to over 40MHz, and changing bands is a
matter of plugging in the appropriate low pass filter kit to attenuate
unwanted harmonic output.
QRSS ... WSPR ... FSK/CW ... DFCW ... Hellshreiber
... CW ... FSK

