Hi, I'm Melissa at Keysight Technologies.
If you're making power integrity
measurements, chances are you need a very
accurate and specific test setup in
order to capture the results you're
looking for. You need something with low
noise in order to prevent getting
false-negative results, something with
really low loading so that your signal
isn't distorted by the probe, something
with high bandwidth so you can catch
high frequency switching loads, and you
also want a way to remove the DC offset so
you can zoom in tight in your signal
without using a DC block, which can
filter out supply drift and other
information in your signal that you want
to observe and capture in your results. A
standard passive probe is not going to
provide all these solutions for you.
So let's take a look at a
standard passive probe compared to a
specialized power probe. Connected to my
S-Series I have two probes. On channel 2 I have
my standard ten-to-one passive probe
and on channel 1 I have my specialty
1-to-1 power rail probe. So let's take a
baseline noise measurement. First I'm
going to zoom in a little bit tighter on
these signals, I'm going to go to 10
millivolts per division on each channel
and then I'll ground each probe
tip so we get a good baseline noise
measurement. I'm just taking off the
clip here and I'll ground the
probe tip with the clip there and then with
my active probe, this is actually a SMA
connector, so I'm going to use my handy
screwdriver to gently make this
ground connection. To
free up my hands I'm going to
stop the acquisition. Now
we've captured that measurement so let's
take a voltage measurement on each of
these. So on the passive
probe we have 26.7 millivolts
of baseline noise. And on
my active probe I've got 1.6 millivolts of
baseline noise, so that's about 20 times
less noise on this power rail probe
than on your standard passive probe.
Now that we've looked at baseline noise
let's look at how immune to noise these
probes are. So if we hold both of
these probes up to the screen we should
see if they pick up noise from our
capacitive touchscreen. You can see
this passive probe is really picking
up a lot of noise, but with this power rail probe
there's just not much going on there.
It's really not picking up any of
the noise from the touchscreen. Let's go
ahead and take a closer look at this.
Let's go ahead and expand our
view, let's separate these into grids,
center the waveforms, just so we can
really get a good look at what's going on.
Both of these probe tips are held
up to the screen and again the passive
probe is really picking up noise where
this active probe is just really not.
It's not picking up any of that noise.
This is really useful in a power rail
probe because you don't want to be picking
up noise spikes like this
because then you could trigger and you'd
get false-negative results. But not only
does it have the noise advantages also
got two gigahertz of bandwidth and
allows you to remove the DC component
without using a DC block which as I
mentioned can filter out supply drift
that you probably want to measure in
your system. The specialty probe I've
been using today is the Keysight N7020A
power rail probe and when you pair
this with the S-Series oscilloscopes,
the result is a really powerful solution.
If you watch my video from several weeks
ago you'll recall that the
a signal integrity of the S-Series
oscilloscopes is amazing.
When you pair an ultra-low noise
scope with an ultra-low noise probe the
result is incredibly accurate measurements
Click the link in the
description to learn more about the
probe and how it can help with your power
integrity measurements.
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