Hi, my name is David Tu. I'm an application engineer with Agilent Technologies, soon to
be Keysight Technologies. In this video today we're going to talk about creating differential
signals with a Trueform generator and we are talking specifically about the 33600A series
generator which I have right here. You know that Waveform generators are really great
for simulating your signals but maybe you have some harder times creating a differential
signal from your Waveform generator. A differential signal is basically just a twisted pair signal
that is isolated. Some of the challenges that you might have for creating a differential
signal is simulating an IC output, to maybe simulating a biomedical signal or maybe just
creating an LVDS, your low voltage differential signal outputs.
So using a Trueform Waveform generator there are some advantages. So (a) it's going to
be really easy to create that differential signal. We have dual channel models to help
with that and they have floating outputs up to 42 volts. Then the other advantage is that
the output range is really great. So you have one millivolts peak to peak to ten volt peak
to peak ranges. So that's going to allow you to simulate quite a few signals.
So let's go ahead and talk about creating that signal. First off we're going to talk
about the hardware. First you need to actually create a cable to do this. So I've got a
cable that has two inputs and then a single output here. So let's go ahead and put up
a picture and describe the single block diagram for this cable. In order to create the differential
signal you have to combine the two channels into a single differential output. You have
to connect the two common connections on the units and then the middle pin of the first
signal of channel one is going to be your high signal and the middle pin of channel
two is going to be your low inverse return path. So that's really all there is for
the hardware.
So let's go ahead and connect this cable up to our unit and our scope. We'll go ahead
and walk you through just creating a simple differential signal. Let's start off by
using a cardiac signal since we had talked about biomedical signals before. So I'm
going to press arb, select arb and just scroll into the built in cardiac signal. Here you
see the simple heart beat. So in order to do the differential portion all you have to
do is press channel one and go to this dual channel button and here we have this tracking
button. So I want to press that and turn on inverted. Press done.
So on the screen you can see that the channel one output is this yellow one. So it's our
normal cardiac signal but you see this new green signal here which is our inverse channel
two signal. So that's our return path. So all we have to do next is just turn on both
outputs and you can see on our scope here that it's our cardiac signal. That's really
all there is to creating a differential signal on a Trueform generator.
So as you can see it's going to save you a bunch of time to create that differential
signal with this. On a generator that does not have this inverted capability and actually
could take you a few hours. You have to create two different arbs, your high going arb and
your low going arb and then you actually have to figure out how to synchronize those two
signals between those two channels. That actually could take you quite a bit of time. With this
feature it's going to take you maybe five, ten minutes if you're unfamiliar with the unit
That's really it. Hopefully you see the advantage of using a Trueform generator with
differential signals. Thanks a lot.