Basic passive microwave components have a vital role in RF/microwave system design. Despite the apparent simplicity of their functions, their performance is based on electromagnetic theory and Maxwell’s equations for insight into their operating principles and performance. Design for the demands of microwave signals is a very different situation than working at lower frequencies. Although […]
RF switches, Part 2: Analog and MEMS switches
Part 1 of this FAQ looked at the venerable electromechanical RF switch – still widely used in some applications, where it is the only viable option—and the use of PIN diodes as RF switches. This part looks at analog and MEMS-based switches. Q: What is an analog switch? A: It’s conceptually straightforward: in basic form, […]
RF switches, Part 1: Mechanical and PIN-diode switches
There’s a ubiquitous and increasing need to switch RF signals ranging into the tens of GHz; four basic switch technologies – electromechanical, PIN diode, analog, and MEMS – are available, each with different features and capabilities. The need to switch RF signals has been a necessary design function since the earliest days of “wireless.” This […]
Filters, Part 2: SAW and BAW devices for RF
Part 1 of this FAQ looked at the basic available electronic filters – analog, switched capacitor, and digital – and briefly reviewed the attributes of each. As the frequencies to be filtered reach to 1 GHz and well beyond, while the selectively needed also became narrower, these filter approaches can no longer support many of […]
MRI, Part 2: historical development (and lawsuits)
The modern MRI system is an amazing blend of diverse technologies, based on the realization that a small but critical aspect of the spin of hydrogen nuclei could be leveraged to provide a safe, non-invasive way to see inside a human body. Part 2 of this FAQ looks at the physics and other advances that […]
Optical amplifiers, Part 2: Basic implementations
Part 1 of this FAQ began an overview into the arcane world of all-optical amplifiers including where and why they are needed. Part 2 will briefly describe the four types and identify the two most commonly used for optical-fiber link signal boosting. Q: How “accurate” will this presentation be? A: Frankly, it will have large-scale […]
Optical amplifiers, Part 1: Applications and considerations
We can now amplify electronic signals from low frequencies to the multi-GHz range without too much difficulty, but amplifying a stream of photons such as in an optical fiber has a very different meaning and is a challenge with no single or easy solution – but it is being done. Electronic and optics technologies are […]
Analog computation, Part 2: When and how
Analog circuits based on op amps can be used to implement mathematical functions and are still useful in many applications due to their unique attributes. Part 1 of this FAQ looked at the basic need for and virtues of analog-based computational circuits. Part 2 looks at some implementation specifics and considerations. Q: What are the […]
Analog computation, Part 1: What and why
Analog circuits based on op amps can be used to implement mathematical functions and are still useful in many applications due to their unique attributes. Say the word “computer” or “computation” and the instinctively associated concept is “digital.” That makes sense since most computers and computation functions are implemented with general digital logic, specialized arithmetic […]
Synthesized tuning, Part 2: Advanced synthesizers and performance
Part 1 of this FAQ looked at the basic issues and topologies related to the challenge of frequency synthesis. Part 2 continues with advanced approaches and their attributes, as well as general concerns when choosing a synthesizer. Q: Are there other digitally-controlled synthesizer topologies? A: Yes. A widely used one is called the classical phase […]