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 […]
Quartz crystals and oscillators, Part 2: Advanced crystals
Part 1 of this FAQ established the context for the quartz crystal as the core of an oscillator whether used as a system clock or as a frequency-setting element in a tuning circuit. This part looks at the achievable performance, the factors that affect it, and what can be done for highest performance. Q: What […]
Quartz crystals and oscillators, Part 1: Crystal basics
An oscillator or clock function is key to nearly all electronic circuits, and in most (but not all) cases, the heart of this oscillator circuit is a tiny piece of quartz, called the crystal blank or slab. It’s easy and commonplace to think of the crystal as a simple component, but as with most components, […]
GPS, Part 2: Implementation
Part 1 of this FAQ looked at the basic principles of the GPS system. Part 2 looks at some hardware circuitry used to implement a GPS receiver as well as the unappreciated role that Einstein’s Theory of Special Relativity plays in providing an accurate GPS. Q What are the key elements of a GPS receiver? […]
20 mA current loops, Part 2: Advanced features
Part 1 of this FAQ looked at the basics of the 20-mA current loop, why it is still used extensively, and its primary attributes. In this part, we’ll look at how the analog current loop is used for digitized signals and at self-powered loops – two developments which have extended its life and viability. Q: […]
20-mA current loops, Part 1: Basic functions
You’ve been given an “easy” assignment: get the low-rate data from a temperature sensor to a control computer located 100 feet (30 m) away, in an industrial setting. After much investigation and assessment, you choose a widely used standard called the 20-mA loop, which has been in use for over 50 years, rather than Wi-Fi, […]
Active noise cancellation, Part 2: Implementation
Part 1 of this FAQ looked at the basic concept of active noise cancellation, how it might be implemented in principle using analog circuitry, and the harsh reality of actually providing the ANC function. Part 2 looks at modern ANC systems and how they function, as well as their practical issues. Q: Is ANC using […]
Analog Top Talks in January on EDABoard.com forums
Peer-to-peer, engineer-to-engineer questions and answers from the EDABoard.com engineering community around analog ICs and analog design. Click the “Read more” link and follow the entire conversation and maybe add your two cents by logging in to EDAboard.com. Flyback diode: it has one job, but mine…? – Please have a look at my simple circuit: And here […]
Top analog threads on EDAboard.com – August
(editor’s note: Intrigued by the problem? Have a question or another solution? Then click the “Read more” link and follow the conversation on EDAboard.com or log in to EDAboard and participate in the analog forum threads.) MOSFET getting very hot – In this schematic, the VCC feed with a less than 1 A MOSFET gets […]
Using the Smith chart for Impedance matching, Part 1
In circuit designs spanning low-frequency audio through high-frequency RF, there’s considerable discussion about impedance matching between components or subcircuits, with various tools such as the Smith chart with is used to facilitate the matching. Q: What is impedance matching? A: Impedance matching means that a signal source sees a load impedance which is the complex […]
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