In the RF signal chain, the power amplifier (PA) is the active element located between the transmitter signal chain circuitry and the antenna, Figure 1. It is often a single discrete component, one with requirements and parameters which differ from those of much of the transmit chain as well as the receiver circuitry. This FAQ […]
basics
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 […]
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 […]
Wheatstone bridge, Part 2: Additional considerations
Part 1 of this FAQ explained the basic principle of the Wheatstone bridge. This part will take the bridge configuration into modern applications and go beyond basic resistance measurements. Q: All this measurement via changing resistance or by measuring current seems very slow or static; how does it fit into today’s electronics? A: First, many […]
Wheatstone bridge, Part 1: Principles and basic applications
Although the electronics industry is relentlessly driven by advances in materials, components, and architectures, the “new” obviously also builds on the “old” and often still uses it, albeit in new guises. There’s still a viable place and need for old devices such as the transformer, solenoid, relay, and Wheatstone bridge. This FAQ will look at […]
Blood oxygen meters, Part 2: IC implementations
It is now trivial and non-invasive to measure blood-oxygen saturation SpO2, thanks to LEDs, algorithms, and ICs for pulse oximetry — it’s a very long way from having to draw blood and send it out for assessment. Part 1 of this FAQ discussed the principle of the non-invasive, light-based pulse-oximetry systems for reading blood-oxygen saturation […]
