A Note From the Editor

Welcome to the year 2022, and Analog Dialogue’s 55th year since its first release in April 1967. The first Analog Dialogue magazines were available only in paper. During my studies my go to source was the book, Electronic Circuits: Handbook for Design and Applications. As students we knew exactly where to find the basics about transistors, bode diagrams, op amps, applications, and so on. What was not in this book pretty much did not exist for us. Now the digital world is more accessible than ever and it’s easy to find all kinds of information through search engines and apps like flipboard, or other services. As we welcome the new year, we are grateful to our readers who have continued to make it possible for us to bring the Analog Dialogue—from print to digital—for 56 years and as always, we’re excited to discuss the latest innovations and technology solutions with you.

And now, let’s look at the articles in this month’s issue of Analog Dialogue.

Various methods exist to measure the concentration of an unknown parameter in a liquid sample, such as pH, fluorescence, or turbidity. A popular method is to evaluate liquids optically, as it is noninvasive and provides stable and accurate results. Precision optical liquid measurements require mixed domain knowledge in electronics, optics, and chemistry. In simple terms, the analysis begins with a sample that is exposed to light from a source such as an LED. After interacting with the sample, the resulting light is processed by a photodiode. This article, “Optical Liquid Analysis Platform Lights the Pathway to Ubiquitous Sensing,” will demonstrate a prototyping platform created for rapid liquid sensing.

The following article, “How to Accelerate Peripheral Monitoring in Low Power Wearables with DMA,” explains the use cases, advantages, and disadvantages of utilizing direct memory access (DMA) in embedded systems programming. The article describes how DMA interacts with peripheral and memory modules for more efficient operation of CPUs. It will also introduce different DMA bus access architectures and the advantages of each. For optimizing power, preserving quick responses to events, and managing large continuous data transfers, a microcontroller with DMA may offer the best solution.

Digital power system managers (DPSM) LTC297x devices are mixed-signal PMBus ICs that can measure and supervise power supply currents. This article, “Current Sensing with PMBus Digital Power System Managers—Part 2,” describes how to measure current on high voltage or negative supply rails and how to set configuration registers for the IMON sensing method. This article covers accuracy considerations of measuring current and provides instructions on programming devices using LTpowerPlay. In part 1, we covered the general concepts of current sensing including the various methods and circuit topologies.

This article, “RF Demystified: Understand Wave Reflections,” is a short discourse for non-RF engineers into the terminology associated with one of the key properties inherent to RF designs—wave reflections. The key difference between the ordinary circuits operating at low frequencies and the circuits designed for RF frequencies is their electrical size. RF designs can be of many wavelengths in size, leading to the variation of voltages and currents in magnitude and phase over physical dimensions of their elements. This gives RF circuits several fundamental properties that underlie the core principles used for their design and analysis.

We continue our StudentZone article series with the article “ADALM2000 Activity: The CMOS Analog Switch.” The objective of this exercise is to explore the use of complementary MOS transistors as an analog voltage switch. The ideal analog switch has no on-resistance, infinite off-impedance, and zero-time delay and can handle large signal and common-mode voltages. Real analog switches made with MOS transistors meet none of these criteria, but if we understand the limitations of analog switches, most of these limitations can be overcome. The on-resistance is one of these limitations and this lab activity will attempt to characterize this switch specification.

And as we have for 56 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.