Designlines’ top test articles of 2011

Here are some of the most popular articles on the “Test & Measurement Designline” Website during 2011.

Colin Holland, Editor, Test & Measurement Designlines -- Test & Measurement World, 1/20/2012 2:51:05 PM

Test & Measurement World is part of UBM Electronics, which also publishes EE Times. The EE Times Website includes several mini-Websites, called “Designlines,” that are dedicated to various disciplines within electrical engineering. Below, I have summarized some of the most popular articles on the “Test & Measurement Designline” during 2011:

• Oscilloscopes and ENOB

While ENOB provides one basis for scope evaluation, ENOB computations don’t include the effect of magnitude or phase flatness. Scopes 1 and 2 have the same ENOB, but scope 2 has offset and phase distortion errors that limit its ability to correctly display the input signal.

One quality metric for an oscilloscope with a bandwidth in the gigahertz range is the ENOB (effective number of bits) of the scope’s ADC. Joel Woodward and Brig Asay of Agilent Technologies discuss the importance of ENOB and how effective it is at predicting a scope’s measurement accuracy (figure).
www.eetimes.com/4216991.

•  Perfect timing: performing clock division with jitter and phase noise measurements
As clock speeds and communication channels run at ever-higher frequencies, accurate jitter and phase-noise measurements become more important, even as they become more difficult to manage. Howell Mitchell of Silicon Labs describes pointers for situations where clock signals have been divided down from higher-frequency VCOs (voltage-controlled oscillators). www.eetimes.com/4219306.

•  A measurement approach for IQ offset and imbalance of LTE mobile devices
Imperfect analog front ends of mobile devices cause transmit signals to be non-ideal. Typically, the signal processing for IQ components is likewise affected. Christian Kuhn of Rohde & Schwarz explains that an estimation of the IQ offset must take into account the special structure of the physical layer of LTE. www.eetimes.com/4229667.

•  Hunting noise sources in wireless embedded systems
When integrating a radio chip or module into a typical embedded system, designers must track down and eliminate noise and spurious signals. Darren McCarthy of Tektronix describes tips and techniques for hunting noise sources using a mixed-domain oscilloscope. www.eetimes.com/4227229.

•  Jitter and timing analysis in the presence of crosstalk
Testing serial data streams for jitter is critical for long-term stability and for achieving a good BER (bit-error rate) in a design. Chris Loberg of Tektronix says to perform an effective analysis, you must select the right instruments and also have a good understanding of instrument noise, rise time, and factors such as 3rd, 4th, and 5th harmonic performance. www.eetimes.com/4233152.

•  DSOs: The banner specs tell only part of the story
Dan Strassberg says an oscilloscope’s performance in capturing anomalous waveforms depends on little-known and often poorly understood characteristics. You might discover that the headline specifications of a scope fail to reveal much of the information you need about the instrument’s behavior. www.eetimes.com/4227286.

•  Vector network analyzers aid breast cancer screening research
Bristol University spin-out Micrima is using high-speed vector network analyzers for the clinical trials of a revolutionary breast cancer screening technique. www.eetimes.com/4230300.

•  Understanding the impact of digitizer noise on oscilloscope measurements
Noise can make it difficult to make measurements on a signal in the millivolt range, such as in a radar transmission. Jit Lim of Tektronix explains how you can use ENOB testing to accurately evaluate the performance of digitizing systems. www.eetimes.com/4217597.

•  Achieving Efficiency in Blood Glucose Meter Design
A glucometer is a medical device for measuring the level of glucose concentration in a patient's blood to determine whether he or she needs a hypoglycemiant drug. Cuauhtemoc Medina Rimoldi describes how a glucometer works. www.eetimes.com/4204495.

•  Design and implementation of a low cost MCU based current loop calibration device
Abdulkadir Çakır, Fırat Yücel, and Hakan Çalış discuss the design and implementation of a low-cost microcontroller-based current-loop calibration device to test and calibrate systems that communicate via the 4-20-mA current-loop standard. For less than $100, they designed a device that has 0.001-mA resolution on the current sourcing The device can both measure and source requested current between the range of 4 mA and 20 mA either in response to an automated step- or ramp-based function or in response to current values entered on a keypad. (A version of the article, “Microcontroller circuit calibrates current loops.” appears in T&MW's Feburary 2012 issue.) 
www.eetimes.com/4230136.  T&MW