You need to test, we're here to help.

You need to test, we're here to help.

08 November 2018

How Tip Inductance Impacts a Probing System's Bandwidth

Shown are FFT plots of a 10-MHz, fast-edge square wave reaching the oscilloscope via direct coax connection  (orange-yellow plot) and 10x passive probe fitted with a coax tip adapter (straw-colored plot)
Figure 1: Shown are FFT plots of a 10-MHz, fast-edge square
wave reaching the oscilloscope via direct coax connection
(orange-yellow plot) and 10x passive probe fitted with a coax
tip adapter (straw-colored plot)
If you're using 10x passive probes with your oscilloscope, it's important to understand the bandwidth of your probing system and how it's affected by various methods of probing the signal of interest. There's a relatively easy way to determine this parameter by probing a fast-edge, 10-MHz signal from a square-wave generator. Doing so can also instruct us in the effects of tip inductance on the probe's bandwidth.

01 November 2018

How Equalization Works in 10x Passive Probes

The adjustable equalization circuit on the oscilloscope end of the coaxial cable compensates for the 10x passive probe's inherent low-pass filter characteristics
Figure 1: The adjustable equalization circuit on the oscilloscope
end of the coaxial cable compensates for the 10x passive
probe's inherent low-pass filter characteristics
We've been discussing 10x passive probes and their inner workings; our last post covered all the ways in which a 10x passive probe is apt to be a liability. They'd be basically unusable for any measurements at all but for one attribute: their equalization circuit (Figure 1). Without it, the 10x passive probe makes a pretty good low-pass filter, but the equalization circuit counters that with a high-pass filter to balance things out.