| |
 |
•
Electro-Mechanical Broadband RF Switch.
• Single-Stage Driver Amplifier •
Quad-Band EDGE Radio Solution • Modeling
3G / WCDMA / HSDPA • Composite Filters
• Integration of Waveguide •
Coaxial Components • Antennas Needed
• And More... |
|
|
|
|
 |
|
 |
| |
 
Low Cost S-Band VCO
A RoHS compliant VCO in S-band, the V804ME17-LF is ideal for fixed wireless applications. It offers a low phase noise performance of -95 dBc/Hz @ 10 kHz offset and covers the entire bandwidth between 0.5 to 4.5V at DC supply voltage of 5V, drawing 20mA (typ.).
AWGN Generator
The NW2.3G2.7AWGN-4S tester for WiMAX and MIMO test applications is now available. The unit is a 4 channel Additive White Gaussian Noise (AWGN) generator designed to add noise to multi-channel receivers. Frequency coverage is from 2.3 to 2.7 GHz.
WiMAX Circulators
Three new circulator designs for WiMAX base stations are high reliability, extended temperature devices with minimal insertion loss. They replace older style crimp components with more reliable screw top designs better suited for mass production with consistent test results.
Digital SP2T Switch
Model SW2-200305RD2NF is a reflective Single Pole Two Throw Switch, covering the frequency range from 20 to 30.5 GHz with a minimum of 30 dB isolation and VSWR of 2:1 maximum. Available options include an extended band version, as well as sub-band versions.
RF Driver IC
A new 20A RF MOSFET driver IC for high frequency switching and short power pulses applications, the DEIC421 from IXYS solves the problems of delay, lead inductance and false triggering due to noise and feedback, which are typical with high current, high speed gate drivers and applications.
Two Way Splitter Combiner
This 2 way splitter combiner drop-in model operates at 2 to 18 GHz, full bandwidth. It operates over the full temperature range of -30 to +80ºC with 10W power handling. Custom parts can be had up to 18 GHz with 25% bandwidth, and the unit can be combined with other embedded functions.
New Oscilloscopes
Ten new oscilloscope models comprise the company’s next-generation InfiniiVision 7000 Series, offering bandwidths up to 1 GHz and delivering an unparalleled deep memory waveform update rate of up to 100,000 waveforms per second.
New SAW Filter
This filter for high-speed wideband cable TV digital tuner applications, built using a new proprietary technique, has enabled CATV tuner, baseband and set-top box manufacturers to build smaller, high performance DOCSIS® 3.0-based high-speed cable modems.
Stripline Circulator
A new surface mount stripline circulator product line was designed for high volume, automated assembly requirements. These low loss, high performance products are currently available in all the major cellular bands. They are not available as isolators.
VXI Instrument Card
A high density, DSP-based, single slot VXI card with modular design that provides up to four synchro//resolver instrument-grade stimulus channels, or up to eight synchro/resolver embedded-grade stimulus channels, and up to six programmable reference supplies is now available. Up to 0.005º accuracy is provided for measurement and stimulus channels.
Ultra LNA Family
A new family of ultra low noise amplifiers with less than 1 dB noise figure across the designed frequency range that are appropriate for a variety of applications including GPS, WiMAX, DAB and MoCA specifications. They are the first products developed on the company’s newest low noise LH3 0.5um pHEMT process.
Sub-Harmonic Image Reject Mixer
A GaAs MMIC sub-harmonic image reject mixer for use in transmit and receive frequency conversion applications, the XM1003-BD is well suited for wireless communications applications such as millimeter-wave point-to-point radio, LMDS, SATCOM and VSAT.
|
|
|
 |
|
|

| |
March 2006
AWGN: Still the Great Enabler
By Ed Garcia,
President, Noisewave Corp.
If you've looked inside microwave test equipment recently,
no doubt you've noticed that there is precious little
microwave hardware inside. A great example is the RF power
meter, which is now an almost completely digital instrument,
except for a little RF hardware in the sensor. In this
environment of "RF digitization," a test tool as simple
as Additive White Gaussian Noise (AWGN) would seem to
be ready for archival in the annals of microwave technology
past. Interestingly enough, that's far from the case,
as noise-based testing is as viable as ever.
Noise is certainly a signal we are all familiar with,
mostly with its deleterious effects. For those new to
the positive uses of "white noise," it is a simple but
remarkably versatile signal that has a constant spectral
density (expressed in watts per hertz of bandwidth) with
a Gaussian amplitude distribution. AWGN can be generated
by several sources, but avalanche diodes are the most
common source used in electronic system testing. When
AWGN is injected into the input of a receiver, it can
quickly evaluate receiver performance and other parameters.
AWGN can be used to simulate a complicated modulation
signal, to purposely corrupt an existing signal, as a
reference signal in other applications, and as economical
source of broadband power.
The Great Enabler
In the 1990s, the availability of coaxial noise sources
with precision, traceable outputs allowed some of the
first digital wireless systems (such as IS-95 CDMA) to
be evaluated in signal environments that were a reasonable
approximation of real-world conditions. Today, digitally-generated
waveforms have to a large degree replaced AWGN as signal
stimuli in cellular and PCS testing, but they simply were
not available back when analog systems were transitioning
to digital. So in a sense, noise-based simulation enabled
the development of digital wireless systems that could
withstand dense, hostile signal environments. Today's
wireless systems employ complex digital modulation schemes
that are evaluated with waveforms and signal densities
that are generated digitally and very closely resemble
real-world operating conditions. Like so many stories
of "modernization," the next sentence in this article
would logically read: "digital waveforms have largely
replaced diode-base noise sources as signal stimuli in
receiver testing." It hasn't happened.
The Leap-Frog Effect
As modulation bandwidths of communications systems increase
to accommodate the higher data rates required of high-speed
transmission, the systems become more susceptible to noise
because more noise power is coupled into the signal. At
the highest frequencies and broadest bandwidths, digital
waveforms cannot be clocked accurately or even generated
at all. The answer: diode-based noise sources, which can
have bandwidths greater than 100 GHz and retain their
precise nature throughout this range.
As they have before, digital signal generation techniques
will ultimately catch up, and noise-based simulation will
step aside, its job complete as enabler of another generation
of system testing. When the next generation ultra-broadband
system appears, noise-based simulation will no doubt be
called upon again, followed by its digital alternative,
and so on.
Unique Needs For Noise
Noise-based testing is not limited to wireless signal
simulation, and has long been a staple in noise power
ratio (NPR), bit error rate (BER), carrier-to-noise ratio
(C/N), and noise figure measurements. To accurately make
these measurements, a precision coaxial noise standard
remains essential. For example, noise sources make BER
testing practical because the required number of errors
can be generated quickly. Without the ability to increase
the number and frequency of errors, it could take a week
and a half to obtain the number of errors required to
determine a system's BER.
Noise sources also make excellent solutions for implementing
Built-In Test (BIT), since they are extremely inexpensive
yet provide a precise reference by which receiver performance
can be measured. Tiny circuit board-mounted noise sources
that inject a signal of a precisely-known power level
and spectral distribution can be switched-in and the receiver
can be checked at various points to determine if it is
functioning properly.
Cable model testing presents another application for noise-based
testing. Hybrid fiber coax (HFC) systems deliver signals
over a broad bandwidth, and are susceptible to noise and
adjacent channel distortion. By testing a modem in the
presence of noise generated by a noise source, the system
can be evaluated and modified if necessary with different
levels of filtering and other remedies.
Digitally-generated waveforms may accurately represent
signal conditions, but at very high frequencies and very
broad bandwidths their effectiveness declines while diode-based
noise sources continue to perform satisfactorily. Digitally-generated
stimuli repeat, unlike natural phenomena that are problematic
at times. In encryption applications this repetition issue
can be solved by using a truly random number generator
derived from a Gaussian noise source. In BER, NPR, C/N,
and other standard receiver tests, noise sources remain
a key element of the test system. The amount of information
that can be transmitted through a communications channel
is a function of the signal-to-noise ratio. The world's
persistent hunger for information forces an almost continuous
need to evaluate performance as a function of signal-to-noise
ratio. In short, noise may not be new and flashy, but
it still provides an elegant solution to the problem of
evaluating receiver systems of every type for their ability
to meet both rated specifications and to glimpse how they
will perform in the so called "real world." To paraphrase
Monty Python,
"Noise is not dead yet!"
NOISEWAVE
www.noisewave.com
Email
this article to a friend!
|
|