編集後記

Welcome to the February issue of Analog Dialogue.

February always reminds me of when I was a student. It was a difficult time, between enduring the cold weather and preparing for exams. Looking back, it is hard to believe I understood all the math involved. Recently our StudentZone articles have offered some more basic challenges with simple passive components—a breadboard and an ADALM1000. Soon we will continue on to the active components and our experiments will become more complex. Please see this month’s StudentZone article about cascaded RC low-pass filters. In the future we will use the ADALM2000 and the ADALM-PLUTO. I am looking for your feedback. Do these topics remind you of your studies?

And now, back to the featured technologies in this month’s Analog Dialogue.

Real-time deterministic Ethernet protocols, such as EtherCAT, have enabled the synchronized operation of multi-axis motion control systems. There are two aspects to this synchronization. First, the delivery of command and references between the various control nodes must be synchronized to a common clock. And second, the execution of the control algorithms and feedback functions must be synchronized to the same clock. The first kind of synchronization is well understood and an inherent part of the network controller. However, the second kind of synchronization has, up to this point, been neglected, creating a bottleneck when it comes to motion control performance. Jens Sorensen, Dara O’Sullivan, and Christian Aaen present a novel concept to synchronize motor drives. From a network controller to the motor terminals and sensors. These technologies enable much improved synchronization leading to significantly increased control performance. Christian, Dara, and Jens are experts in motor control and power conversion. As those applications are increasingly connected to the cloud, time sensitive networks (TSNs) also become an important topic for engineers.

The discovery of X-radiation by Wilhelm Conrad Röntgen in 1885 earned him the first Nobel Prize in Physics and laid the historical foundations for the field of medical imaging. Since then it has developed into an extensive scientific discipline that, in its widest sense, designates diverse techniques for noninvasive visualization of the internal aspects of the body. The data converter constitutes the most demanding challenges imposed by medical imaging on the electronics design. In his article, Anton Patyuchenko discusses the design challenges in a context of different imaging modalities including digital radiography, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US), and positron emission tomography (PET) devices. Anton is a field applications engineer in EMEA specializing in healthcare, energy, and microwave applications.

High power LEDs continue to proliferate in modern lighting systems, spanning automotive headlights, industrial/commercial signage, and architectural lighting, as well as a variety of consumer electronics applications. As LED lighting is incorporated into an expanding array of applications, the demand for higher LED currents for increased light output also grows. One of the biggest challenges for powering these high currents is achieving high efficiency power conversion to prevent unwanted heat. Close to 95% efficiency is reachable with the application described by applications engineer Kyle Lawrence in this Analog Dialogue article. He is responsible for the design and testing of a variety of dc-to-dc converters, including 4-switch buck-boost voltage regulators and LED drivers targeting low EMI automotive applications. Kyle received his B.S. degree in electrical engineering from the University of California, Santa Cruz in 2014.

You probably know from your electric toothbrush that a wireless power transfer system is composed of two parts separated by an air gap: transmitter circuitry with a transmit coil, and receiver circuitry with a receiver coil. Like in a typical transformer system, alternating current generated in the transmitter coil induces alternating current in the receiver coil via magnetic field. Most wireless power applications in use today are configured as wireless battery chargers. A rechargeable battery resides on the receiver side and is charged wirelessly whenever in the presence of a transmitter. After charging is complete and when the battery is subsequently taken off of the charger, this battery then powers the end application. What if you do not have a battery in your end system? Mark Vitunic, a design manager in Analog Devices’ power business unit, will answer this question in the featured RAQ. Mark joined ADI in 2017 following the acquisition of Linear Technology, where he had worked for the previous 19 years. His focus is on wireless power transfer, ultra-low power ICs, energy harvesting, active battery balancing, and multichannel dc-to-dc regulators. Mark holds B.S. and M.S. degrees in electrical engineering from Carnegie-Mellon University and the University of California at Berkeley.

Next we move on to the StudentZone, which discusses how if two passive RC low-pass filters are cascaded, the frequency response is not simply the product of the two first-order RC transfer functions. This is because the ideal single-pole response assumes that a zero-source impedance is driving the filter and that there is no load on the output (that is, the filter drives an infinite impedance). However, directly connecting the second filter acts as a load for the first, effectively changing the combined RC time constant. If you try to analyze the cascaded circuit by simply adding phasors you will soon realize the shortcomings of that simple technique. We will expand the series to include active components and, starting soon, we will also introduce you to the ADALM2000. Doug Mercer and Antoniu Miclaus are committed to guiding us through this series. I hope you enjoy the new session. Good luck in your studies.

And as we have for 52 years, we invite you to be part of the “dialogue” in Analog Dialogue. You can get in touch through our blogFacebook page, or email. Let us know how we’re doing and what you’d like to see from us in the coming months.