Feedback is a term that describes comparing the actual output of a system to the desired output and adjusting the actual output to produce the desired end result. For example, the human nervous system provides constant feedback to the brain, especially when pain is felt for avoiding further bodily harm. In electronics, feedback is defined […]
FAQ
How much math do you need to know to design electronics?
Education for electronics design tends to have a fair amount of math in it but how much is really required nowadays in order to design electronics? You certainly need some, but a high percentage of what you learn at college or university is likely to be unused once you leave, although this does depend on […]
Interfacing and using bridge sensors
Sensors such as strain gauges, pressure gauges and some magnetic sensors are often bridge devices. They can be full or half bridge although the bridges are usually made of multiple devices connected together, with MEMS sensors being an exception. So, in the case of a strain gauge, a half bridge would be made with one […]
Signal line and supply filtering
There are many reasons for needing to filter power supply or signal line. Power supply lines from a switching regulator may be too noisy for sensitive analog circuitry. Signal or power supply lines may pick up interference either from the rest of the system circuitry or from external devices. With signal lines the problem of […]
Troubleshooting analog circuits
While you may need to troubleshoot a circuit that used to work and now doesn’t, the emphasis here is how to troubleshoot a design when you have your first PCB made. While you may be fortunate and everything works perfectly first time, there is often a need for some troubleshooting with a new design. The […]
When inductors self resonate
Inductors only behave like inductors below because of what’s called their self resonant frequency. And the self resonant frequency arises because the equivalent circuit of real-world inductors isn’t strictly inductive. There are parasitic elements that come into play. To understand why, look at the equivalent circuit for an inductor. An inductor can be comprised of […]
Variable gain amplifiers
It is not uncommon to need an adjustable gain in an analog signal processing chain. If the adjustment is manual then it is pretty straightforward — you can use a potentiometer. When you need the adjustment under digital control then it becomes more complicated. If you need a digitally adjustable instrumentation amplifier then there are […]
Calculating and comparing amplifier noise
I was recently presented with the problem of comparing the noise of two alternative designs that were presented to me. Normally that wouldn’t take much sorting out – a few minutes with a SPICE simulator and you would have the answer. That depends on having reliable SPICE models. The first thing I do when embarking […]
Level shifting digital logic signals
In the past digital systems were 5V and analog ones +/-15V or +/-12V. Nowadays analog systems are more likely to be single supply 5V, 3.3V or lower and digital circuitry is likely to be 3.3V, 2.5V, 1.8V, 1.2V or something in between. You might also have LVDS, DDR or other differential or single ended standards […]
Choosing, using and designing oscillators
Most electronics today have oscillators in them. Digital circuitry needs a clock. Radio frequency signals require an oscillator or clock. Some analog circuitry also needs a clock or oscillating signal source. If you are using a microcontroller then it might have a built-in clock, although it may not be accurate enough, depending on your application, […]
