編集後記

Let’s talk about competition—no, it is not industry competition I have in mind. I am talking about a game of family chess! I learned chess from my father. I remember playing a couple of chess games during the weekend. It was a casual event between the two of us that involved having a chess match after lunch. My father learned chess from his father, my grandfather. During family events, quite often, the chessboard was already prepared on arrival. Looking back, it was a great spirit-filled activity, a relaxing time, and a nice tradition. Now, during COVID times, we extend this tradition but instead of having a live game, my son and I meet virtually at an online chessboard. It is a relaxing break at the end of a day, and I am proud to admit that I am losing the majority of the chess games against him. I am sure there are family traditions like this around the world. How have you continued the traditions in your country?

And now, back to the Analog Dialogue articles.

It was not so long ago that RF engineering was an emerging discipline. Today RF technology is so deeply ingrained in our lives that it is inconceivable how modern civilization could survive without it. Communication and transportation, industrial automation and healthcare, aerospace and defense are all areas heavily relying on the RF technologies that underpin any RF signal chain, which is the central theme of this article, “RF Signal Chain Discourse: Properties and Performance Metrics.” We all know that RF stands for radio frequency, and a common definition ties this term to a specific range of frequencies extending from MHz to GHz portions of the electromagnetic spectrum. If we take a closer look we come to realize that the actual boundaries of the RF portion of the spectrum are defined differently. Then what is RF?

In Part 3 of our CTSD Precision ADCs article series, we will highlight the “alias free” nature of new CTSD ADCs, which improves the immunity to interferers, or signals outside the signal bandwidth of interest, without any added periphery design. The key challenge for signal chain designers is that the ADC sampling phenomenon causes these interferers to alias into the signal bandwidth of interest (in-band) and degrade performance. The solutions to reject these aliases are one of the reasons why traditional ADC signal chain designs are quite complex. The unique inherent alias rejection property of new precision CTSD ADCs provides a simplified solution. This article, “CTSD Precision ADCs—Part 3: Inherent Alias Rejection Made Possible,” compares the complexity of alias rejection solutions for currently available precision ADC architectures.

We began our signal chain power series with the article, “Optimizing Power Systems for the Signal Chain—Part 1: How Much Power Supply Noise Is Tolerable?” We examined how power supply ripple noise can be quantified, and likewise, how these quantities can be connected to real effects in the signal chain. As noted, a pure focus on minimizing noise can come at the cost of increased size or lower efficiency. In the next article, “Optimizing Power Systems for the Signal Chain—Part 2: High Speed Data Converters,” we build on a generalized overview of the effects of power supply ripple in high performance signal chains. Part 2 dives deeper into the details of optimizing power distribution networks for high speed data converters. We compare a standard power distribution network to an optimized network to see where improvements can be made. Subsequent articles will explore specific optimization solutions for other signal chain devices, such as RF transceivers.

EMI performance is critical in noise-sensitive systems, especially when switch-mode power supplies are involved. In particular, the FM band (76 MHz to ~108 MHz) is sometimes the most difficult and last band to get enough EMI reduced to pass the EMI tests. Why is the high frequency FM band so difficult to mitigate? Low frequency (AM band) conducted emissions are dominated by differential-mode noise. High frequency conducted emissions are dominated by common-mode noise. Common-mode noise current is generated by nodes with changing voltages on the PCB. The current leaks through stray capacitance to reference ground and back to input plus and minus cables. Due to the complexity of stray capacitance around the PCB, it is not practical to simulate stray capacitance and estimate FM band conducted EMI. However, one simple approach is to test the board in the EMI chamber. This approach will be discussed in the article “RAQ Issue 188: Mitigation Strategies for Tricky FM Band Conducted EMI.”

In previous StudentZone articles, “ADALM2000 Activity: Zero-Gain Amplifier (MOS)” and “ADALM2000 Activity: Common Emitter Amplifier,” we outlined how to use transistors as current mirrors. In this month’s “ADALM2000 Activity: The Emitter Follower (BJT),” we will introduce you to another basic usage of a transistor—the simple NPN emitter follower (BJT) amplifier, also sometimes referred to as the common collector configuration. As always, we are using a breadboard and the ADALM2000 Advanced Active Learning Module.

And as we have for 55 years, we invite you to be part of the dialogue in Analog Dialogue. You can get in touch through our blog, Facebook page, or email. Let us know how we’re doing and what you’d like to see from us in the coming months.