Antennas based on fractal mathematics offer some significant advantages but also some controversy. The first part of this article looked at the basic concept and history of fractals. This part looks at the relationship between fractals and antennas. Q: All this fractal discussion is interesting, but what does it have to do with antennas? A: […]
FAQ on fractal antennas, Part 1
Antennas based on fractal mathematics offer some significant advantages but also some controversy. Although all antenna designs are derived from either the basic dipole or monopole/ground-plane configurations, there are almost countless antenna variations in use (Figure 1). Each one offers a different combination of key attributes such as center frequency, bandwidth, bandwidth, side lobes, front-to-back […]
Zero-drift amplifiers finesse ultralow-frequency signals, Part 3
Modern zero-drift amplifiers provide the extremely low drift and noise performance, needed for processing many optical biological, and physical-world signals near 0 Hz. Contrary to what you might think, mechanical chopping is still alive and useful. Given the outstanding performance of electronic components, using a high-performance zero-drift amplifier seems the way to go. That is […]
Zero-drift amplifiers finesse ultralow-frequency signals, Part 2
Modern zero-drift amplifiers provide the extremely low drift and noise performance needed for processing many optical biological, and physical-world signals near 0 Hz. The ultimate limitations of chopping led designers to investigate another approach called auto-zeroing, which is especially feasible with integrated circuits. This is a dynamic correction technique that works by sampling and subtracting […]
Zero-drift amplifiers finesse ultralow-frequency signals, part 1
Modern zero-drift amplifiers provide the extremely low drift and noise performance needed for processing many optical biological, and physical-world signals near 0 Hz. In our world of ever-faster, wider-bandwidth signals and systems operating at higher and higher frequencies, it may seem that signals in the very-low-frequency range — down towards zero hertz (0 Hz) — […]
Minimizing electrical noise to improve medical-ultrasound images, Part 3
Low-noise circuitry is critical to image quality of medical ultrasound, an indispensable diagnostic tool. Efficiency versus noise It may seem that if there is a tradeoff between power-supply noise versus potential efficiency, the need for ultralow noise in the ultrasound application should prevail. After all, a few more tens of milliwatts of dissipation should not […]
Minimizing electrical noise to improve medical-ultrasound images, Part 2
Low-noise circuitry is critical to image quality of medical ultrasound; an indispensable diagnostic tool. Despite the conceptual simplicity of the underlying principle, a complete, high-end ultrasound imaging system is a complicated device (Figure 1). The ultimate performance of the system is largely determined by the transducer and analog front end (AFE), while post-processing of the […]
Minimizing electrical noise to improve medical-ultrasound images, Part 1
Low-noise circuitry is critical to the image quality of medical ultrasound, an indispensable diagnostic tool. Ultrasound technology, a widely used non-invasive tool in medical diagnostics and other applications, has shifted from static to dynamic images and from black-and-white to color Doppler images. These important enhancements are largely due to the introduction of digital ultrasound technology […]
When reality intrudes on component models and equivalent circuits
Determining the utility of an equivalent-circuit model versus construction reality is often a difficult challenge. Using simplified, first-order approximations in models and equivalent circuits is a normal part of engineering life. Without them, we would get mired in the details and harsh reality of the components and their characteristics. We would never be able to […]
What are digital twins, and where are they on the “hype cycle”?: Part 2
Digital twins are getting lots of deserved attention, but are they the cure-all for whatever simulation issues you have? Although digital twins are undoubtedly valuable tools along with basic simulation, modeling, HITL, and others, the associated all-good/no drawbacks promotion concerns me. When a tool, product, or other development gets a lot of “pumping up” to […]
