top of page

Characterizing LED Performance with a Frequency Response Analyzer and Line Injector

This application note series by Steve Sandler explores the measurement of the dynamic resistance of an LED and how to create a usable SPICE model from the data. Today, LEDs dominate the lighting industry, replacing incandescent, CFL, and halogen bulbs. They are much more efficient at saving power, and as semiconductor devices, they should be much more reliable. Most LEDs are powered by constant current drivers in order to maintain uniform lighting in parallel strings with mat

Measuring a Scope Probe Requires Two Oscilloscope Channels and a Very Flat Signal Source

Oscilloscope users can also calibrate their passive oscilloscope probes, though the process is much less sophisticated and for lack of a better term, wrong.  The calibration process also generally can’t include the “fixture.” This short article shows you what to measure and a method to accurately measure the response of the probe.  In addition to the probe, there are other errors that need to be removed.  Most importantly, this article will show you how to accurately measure

Match impedances when making measurements

Recently, I used a shielded coaxial cable to measure power supply ripple and the results were even noisier than using an oscilloscope probe. How can that happen? Doesn’t the shielding reduce noise? I even measured my setup using a signal generator and it all looks ok. So what was wrong? On the surface, it seems like a great idea to use a shielded cable to measure noise. In reality, it is a great idea to use a coaxial cable to measure ripple and noise and you can gain the bene

Why Network Analyzer Signal Levels Affect Measurement Results

When measuring a circuit or device with our network analyzers, engineers generally inject a signal and believe that the measured results reflect that of a small?signal AC measurement. Many of us have been taught to keep the signals “very small”. This raises the questions, “how small is very small” and “is this an issue with my network analyzer”? SPICE based circuit simulators use partial derivatives to perform small?signal analysis, and therefore, are not sensitive to the sig

FAQ #16: What Calibration Services do you offer?

What Calibration Services do you offer? Apart from warranty repairs, calibration and servicing, done directly at Picotest, we work with Precision Metrology, a calibration and repair service based in Milwaukee, WI (7350 North Teutonia Avenue Milwaukee, WI 53209 414-351-7420). They are one of the largest independent calibration houses in the country. They are fully ISO 9001 certified and A2LA accredited. See list of accreditations via this form : http://www.precisionmetrology.c

FAQ #8: Why do I have to calibrate my measurements? Isn’t the equipment calibrated?

Why do I have to calibrate my measurements?  Isn’t the equipment calibrated? Yes the devices are calibrated, however for accurate results you still need to calibrate the measurement itself.  The purpose of the calibration is to eliminate any influences caused by the probes or other cabling.  The calibration nulls any errors in gain or in phase.  The calibration is very simple.  Fr gain measurements connect the two probes to the same point in the circuit and perform a THRU cal

Blog: Blog2
bottom of page