Scope Guru on Signal Integrity
Jit Lim, Tektronix senior technologist for high-speed signal analysis, has an EE degree from the Massachusetts Institute of Technology and more than 20 years of experience in the test-and-measurement industry. He has also designed some of Tektronix's highest-performance real-time scopes and published numerous technical papers. Lim brings his extensive experience in signal integrity, jitter measurement, and high-speed-signal physical-layer characterization to these blog posts.
A window into the frequency domain, part 2
From guest blogger Gina Bonini: In my last post, I reviewed windowing factors used during scope FFTs—why they’re needed, and how to select the right one. In this post, I’ll continue down the path of reviewing key tidbits about the scope FFT function, an often confusing and somewhat mysterious topic. One of the biggest concerns when performing an FFT is aliasing. Aliasing occur ...... Read More
Comments (2)A window into the frequency domain
From guest blogger Gina Bonini: For a recent project, I had to blow the dust off the front cover of my Discrete Fourier Transform (DFT) book from college. I actually have a few DFT books, acquired throughout my career from a variety of sources. Each one of these books is relatively thin but packed with equations and higher-order math, which makes cracking the cover and trying to “remember&# ...... Read More
Comments (0)A night at the circus
From guest blogger Gina Bonini: I spent my Saturday night at the circus–Cirque Du Soleil, to be exact. I’ll admit it; I’m a big circus fan. To watch human performers do death-defying stunts, and push their bodies to a level beyond what mere mortals can do, is entertaining and inspiring. Cirque Du Soleil is unique in that it is also a major theater production with music and lig ...... Read More
Comments (2)Probing: It's not always about bandwidth
From guest blogger Randy White: Choosing a scope probe or understanding how to use one may not be as straightforward as you might think. For example, the Tektronix P2220 is one of the most common passive voltage probes, yet there are many factors to consider. The data-sheet spec section for this probe states, “200 MHz bandwidth, 10x/1x attenuation, 17 pF input C, and includes a 6 inch groun ...... Read More
Comments (0)Living the pipe dream at Design West
From guest blogger Randy White: Remember that animated video of the pipes and balls with synchronized music? The video is called “Pipe Dream” and was made about 11 years ago. Below is a screen shot from the video in case you’re not familiar with it. Last week at the 2012 Design West show in San Jose, attendees were treated to a “live” version of this video. This ...... Read More
Comments (0)Approaches to testing 100G networking equipment designs
From guest blogger Chris Loberg: With 100G networking topologies becoming more common, network equipment suppliers and designers at all levels of the supply chain are beginning to evaluate their approach to verification and compliance testing. Many of the 100G demonstrations at OFC 2012 focused on testing four-lane (4×25G/4×28G) implementations with electrical/PHY tests on a couple of ke ...... Read More
Comments (0)Ensure maximum signal fidelity with good solder-in probe connections
From guest blogger Chris Loberg: In my last post on LPDDR memory, I talked about the importance of observation-point accuracy to provide a solid platform for signal acquisition. With chip designs getting microscopic in size and faster in clock frequency, it’s more important than ever to have this nailed for accurate PHY-layer electrical verification and compliance testing. In addition to fi ...... Read More
Comments (0)Increasing performance and battery life in mobile devices
From guest blogger Chris Loberg: The latest arena to address improvements in mobile-device performance is memory systems. JEDEC is pushing forward with specifications for the LPDDR3 memory interface, which will operate at an all-time low of 1.2V. What LPDDR3 brings to the table for mobile-device designs is faster read/write speed and a tighter package accompanied by a lower drain on batteries.The ...... Read More
Comments (1)Taking measure of OFC 2012 trends
From guest blogger Chris Loberg: After three days at the OFC (Optical Fiber Communications) Conference in Los Angeles, it’s clear that the optical market is showing promising progress in both innovation and adoption of new technologies to improve bandwidth utilization. First, 100Gb/s networking equipment using DP-QPSK modulation techniques was commonplace at the event. Also very prevalent a ...... Read More
Comments (0)Jitter analysis under the hood: Rj/Dj decomposition
From guest blogger Randy White: In my last post, we took a look under the hood at how jitter-analysis packages handle clock recovery. In this post, I explore the task of separating total jitter (Tj) into individual components, focusing on separating out random jitter (Rj) and deterministic jitter (Dj). Let’s start by taking a look at some advantages of oscilloscope-based jitter analysis: Sp ...... Read More
Comments (1)Looking under the hood of a jitter-analysis engine
From guest blogger Randy White: Teardowns are popular these days for the latest consumer devices, but why doesn’t anyone do a teardown of the latest jitter-analysis packages? A comment from the last blog entry about how measurements correlate across different instrument vendors brought this to my attention. It’s a very good question worth exploring. Any tool, whether simple or compli ...... Read More
Comments (2)Measuring propagation delay in a device
From guest blogger Gregory Davis: In logic devices such as buffers and comparators, a parameter of interest is the propagation delay or response time. This is the time it takes for the device output to respond to an input signal. Often, the specifications for propagation delay are not easy to find, or a range is given that is so wide it’s hard to determine how much margin you actually have. ...... Read More
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