The previous parts of this article explored the photomultiplier tube (Part 1 and Part 2), which is based on a simple, fairly clear physics principle, although building a high-performance PMT is an art and requires various skills, of course. This part looks at a microwave/mm-wave amplifier called the traveling wave tube (TWT – often pronounced […]
Vacuum tubes we still (have to) use: The photomultiplier tube, Part 2
We live in a world of solid-state active devices that have made most vacuum tubes obsolete, but a few types remain as they are still indispensable. Part 1 of this article explained the basics of the photomultiplier tube. This part looks into other PMT characteristics. Q: Are there solid-state functional equivalents to the PMT? A: […]
What are the applications and measurements of S-parameters? (Part 2)
Part 1 of this FAQ was a basic introduction to the context and concept of s-parameters. Part 2 looks at their measurement and application and relationship to the time domain. Q: How do you actually measure s-parameters? A: In general, except for approximate measurements, you cannot use a spectrum analyzer alone for this frequency-domain test. […]
What are the functions and principles of S-parameters (Part 1)?
As design frequencies now routinely go into the hundreds of MHz and tens of GHz range, conventional voltage and current measurements are not useful, but scattering (s) parameters can fully characterize the RF component or path performance. For engineers with experience focused from DC to several hundred megahertz, it is usually sufficient to characterize components […]
Fluxgate compasses, Part 2 – Issues and enhancements
Part 1 of this FAQ examined the underlying context of fluxgate compasses and navigation, as well as the basic principles of the fluxgate design. This part looks at additional fluxgate-compass issues and advances in their implementation. The fluxgate compass is fairly simple in principle. However, as with all things related to magnetism in general and […]
Fluxgate Compasses, Part 1 – Context and principles
Despite the availability of GPS and inertial measurement units, the compass in an electronic fluxgate implementation is still a viable and needed navigational tool. The classic magnetic-needle compass is not getting much respect or attention these days. Between the Global Positioning System (GPS) and the Inertial Measurement Unit (IMU) system, the compass – whether it […]
Printed Circuit Boards, Part 4: Beyond FR-4
Part 4 concludes this FAQ with some fabrication issues and at substrates with performance which is multi-GHz-compatible and goes beyond that available using FR-4 material. Q: What’s the set-up situation for PC board fabrication? A: The production-level fabrication process is optimized for runs of tens, hundreds, and thousands of boards, as there is a set-up […]
Printed Circuit Boards, Part 3: Vias and multilayer boards
Part 1 of this FAQ series looked at the ubiquitous FR-4 PC board as well as other PC board issues, and Part 2 reviewed highlighted some of the board issues and the widely used FR-4 PC board substrate. This third part looks at advanced PB board issues such as vias and multilayer boards. Q: How […]
The basics of FR-4 Printed Circuit Boards
Part 1 of this FAQ provided context and background on the PC board, and discussed its first widespread appearance as a phenolic-based board. Part 2 looks at some board issues and the widely used FR-4 PC board substrate. Q: I see the term “solder mask” — what is that? A: Solder mask (also called a […]
Printed Circuit Boards, Part 1: Context and phenolic boards
Despite appearances, there’s nothing simple about the materials or fabrication of the ubiquitous PC board, and the requirements of multi-GHz systems are increasing the performance demands placed on these boards. We take the standard, usually green, printed circuit board (PC board or PCB) for granted, but it has an interesting history, alternatives, and future. This […]
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