The cathode ray tube (CRT) is what made possible TVs, computer monitors, and oscilloscopes as we know them. CRTs have largely been replaced by flat-screen technologies but CRTs still serve in niche applications. For example, some kinds of military needs still require a CRT display. General-purpose CRTs are no longer manufactured in the U.S., but […]
FAQ
Memory technology from Floating Gates to FRAM
There are two basic types of memory: volatile and non-volatile. Volatile memory loses its content and becomes a blank slate whenever power is completely removed. However, volatile memory doesn’t need much power and can maintain its contents with a small battery. Non-volatile memory retains its contents even if power is completely removed. SRAM and DRAM […]
Measuring oscillator jitter
In digital electronics, jitter is a particularly insidious form of noise, to be understood, measured and where possible mitigated. Jitter is short-term, generally considered less that one second, deviation from the design intent. It consists of timing fluctuation in periods or transitions within cycles. An eye diagram tells the whole story. While vertical closing of […]
Impedance matching and the Smith chart, 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 […]
Options for current sensing, Part 2
Part 1 of this FAQ discussed the issue of current measurement, and four transducers which can be used to measure current. The first two – shunt resistors and Hall-effect devices – can be used for AC or DC currents. We will now look at two other transducers – the Rogowski coil and the current transformer […]
Measuring active and passive filters
The usual rationale for a filter in electronic circuitry is to reject unwanted portions of a spectrum or at least reduce their amplitudes to acceptable levels without attenuating the desired frequency or range of frequencies. In some situations, active filters are needed to perform this function, and often they are less expensive than alternate solutions […]
A look at the computer engineering stack
The embedded world looks a lot like the computing world as technology evolves, so it’s worth taking a look at the full computer engineering stack. This kind of stack refers to the structures built on top of each other that combine to form computers, not the memory register stack that processors use and can sometimes […]
Mechanical vibration for electronics: the quartz crystal
It is now 100 years since Alexander Nicholson at Bell Telephone Laboratories built and patented the first crystal oscillator, and crystals are still the main source of accurate oscillations up to UHF frequencies using quartz instead of Rochelle Salt (see US patent 2212845). Quartz crystal oscillators use the piezoelectric effect. The piezoelectric effect refers to […]
What’s the difference between an analog switch and digital switch ICs?
Analog switch integrated chips (ICs), then turned on, will conduct both analog and digital signals from the input pin to the output pin. Digital switches can only accept digital signals and duplicate the logic level on the input pin at the output pin. When the digital switch is turned off, it returns to a default […]
The importance of Fourier Transforms
I have mentioned Fourier transforms in other posts but it is probably worthwhile explaining more about Fourier transforms in order to show why I think they are so important to analog signal processing. You may come across several theorems containing the name “Fourier” such as the Fourier Series, Fourier Transform, Fourier Integral and Fourier Analysis. […]
