Most of us learned how to use a function generator in our first hands-on
engineering class. They are staple on any electronics bench. In general they're
pretty easy to use if you only need to source one signal but it can be a bit
cumbersome if you're trying to coordinate multiple inputs. If you're in
an automated testing environment, trying to coordinate multiple function
generators can also make your code more cumbersome. So today we're going to look
at how to coordinate or couple together at multiple function generator outputs.
Here we have a dual output function generator piped into an oscilloscope so
we can see the function generators outputs. We can actually couple the
outputs together using dual channel operation. To turn on dual channel
operation select a channel, hit more, and then turn on Dual Channel and you'll see
we have a Dual Channel Operation Menu and if you look at this we can couple
the frequency, we can couple the amplitude, and if we turn on frequency
coupling, we can even set a frequency ratio between the two channels.
So I'm going to set this ratio to two so channel two is going to have double the
frequency of channel one and then notice if I go in and change the frequency of
channel 1, channel 2 is automatically going to be adjusted. So these channel
frequencies are now coupled together with one simple control. One situation
where this is often used is in the testing of differential gain amplifiers,
by syncing the frequencies you can see how your amplifier responds to different
inputs. Here the flatness of channel one shows us that the amp is working
properly and here we can see the differential amplifiers response when
the differential inputs aren't perfectly in line. In this case channel one has a
two to one frequency ratio. This could also be useful if you want to maintain a
90 degree offset for IQ data or mix together two outputs to create one multi
frequency signal, especially if you're using ARSM. For example testing the pulse
rejection characteristics of a pacemaker. For more tips on using waveform
generators check out the app notes over in the waveform generator section.