Wireless sensor nodes, wearables, trackers, and displays are typical devices that can be powered using energy harvesting (EH), also called ambient energy, energy scavenging, or power harvesting. The availability of ambient energy for harvesting varies depending on the location and environment where the device is used. Among the many possible sources of ambient energy, the […]
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Practical measurement of feedback loops and their stability
Feedback is relevant not only to electronic circuits but also to all kinds of natural and human-based phenomena ranging from mechanical engineering to economics and finance. Feedback emerges when one or more system outputs are connected back to system inputs. If polarity is inverted, it is an instance of negative feedback, which in electrical circuits […]
Basics of CMOS and measuring CMOS logic parameters
Complementary metal-oxide semiconductor (CMOS) fabrication uses p-type and n-type complementary and symmetrical pairs to implement logic functions. The fundamental building block of the CMOS circuit is the MOSFET semiconductor, which enables it to operate at far lower current levels than bipolar transistors. This current reduction comes via pairs of p-type and n-type MOSFETs connected gate-to-gate […]
Class D audio, Gallium-Nitride versus Silicon – Virtual Roundtable (part 2 of 2)
In this second part of EEWorld’s “virtual roundtable” discussion on Class D audio, our panelists delve into the impact that the emergence of gallium-nitride (GaN) is having on Class D designs: Where are silicon devices still dominant? What are the performance benefits of using GaN in Class D amplifiers? And what are the anticipated future […]
Class D audio technology and applications – Virtual Roundtable (part 1 of 2)
The first part of EEWorld’s two-part “virtual roundtable” discussion on Class D audio considers technical challenges and design trade-offs for engineers using Class D audio technology. Joining us for this virtual roundtable are: Joshua LeMaire (JL), Audio Systems Architect at Analog Devices; Steve Colino (SC), Vice President Strategic Technical Sales with Efficient Power Conversion; and […]
Sorry, but it’s “Goodbye, Caboose” – EoT devices have made you obsolete, Part 2
Part 1 of this article discussed the concept and basic implementation of the end of train (EOT) device. This part explores the EOT and its larger “ecosystem” in more detail. First, a bit of history While the first caboose replacement was a simple flashing rear-end device (FRED), first used by the Florida East Coast Railroad […]
Sorry, but it’s “Goodbye, Caboose” – EoT devices have made you obsolete, Part 1
The venerable-freight train caboose of history has been made obsolete over the past few decades by sophisticated, rugged, electronic end-of-train (EOT) devices which do much more, much better, and much cheaper. Ah, the caboose (Figure 1): it’s a railroad car which combines practicality, utility, legend, imagery, history, nostalgia, romance, dreams, myths, and so much more. […]
Hysteresis and its measurement
Hysteresis might be defined as something that happens when the physical state depends upon its history. The classic example of hysteresis in action is the residential thermostat. It has built-in hysteresis to prevent rapid cycling. It’s low cut-in and high cut-out levels are designed to prevent the heating/cooling system from rapid switching, which would quickly […]
RF/Microwave bandpass filter implementations, Part 3: microstrip, coaxial, and helical filters
Part 2 looked at two types of RF/microwave filters, but there are many more, including ceramic coaxial filters and helical filters. They are discussed in this part. Microstrip filters Microstrip filters are built as a carefully defined pattern on a PC board. There is almost no limit to the filter designs which can be built […]
RF/Microwave bandpass filter implementations, Part 2: Cavity and comb filters
The well-known and extensively analyzed lumped-element bandpass filter is generally not suitable for the RF/microwave region, but there are many distributed-element, energy-based alternatives. Part 1 of this article established the context for these RF/microwave filters, which operate in the spectrum from several hundred MHz and higher, and increasingly cannot use discrete lumped-circuit elements (RLCs). Instead, […]