HP 81200, User Manual, Page: 115 / 240

How to Set Up a Port or Channel for Generated Signals Setting Up Ports and Channels
HP 81200 Data Generator/Analyzer Platform User Guide, Revision 2.1
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5
Activate the connection: This is probably the most important step of all!
T I P
When running a test, check the green LEDs of the frontends. They indicate
whether the channel is enabled or disabled.
6 Close the window.
How to Add Channels in Analog Mode
If you have chosen an HP E4838A frontend, the Parameter Editor shows an
additional tab: Analog Channel Add . This tab provides a window with
additional parameters which take effect as soon as you add the channel to
the channel above in analog mode (see “How to Combine Generator
Channels” on page 124 ).
Figure 46 Analog Channel Add Parameters
The window illustrates how the analog channel addition works.
You are adding two differential signals. A differential signal consists of an
OUT and a complementary OUT voltage. Both signals can have different
slew rates (rise/fall times) and amplitudes (the voltage difference between
high and low level).
But the output voltage of the E4838A frontend at 50
τ
load is limited to
–2.2 V to + 4.4 V, and the output voltage swing must be in the range of
0.05 V to 3.5 V (for details refer to the HP 81200 Technical Specifications ).
So we keep the high level voltage of the frontend that holds the connector.
That means, the connected channel’s high level voltage is only reached
after adding the two OUT channels. The amplitudes Amp1 and Amp2
remain unchanged, and the resulting voltage swing of the signal is the sum
of both amplitudes.
A similar scheme applies to the complementary OUT connector.