As shown below, the 33120A has a fixed output source resistance of
50 ohms. During calibration, output amplitudes are calibrated for both
the open-circuit voltage (no load) and the terminated output voltage
(loaded). The terminated output amplitude is calibrated for an exact
50 ohm load. Since the function generator’s output resistance and the
load resistance form a voltage divider, the measured output voltage of
the function generator will vary with load resistance value and accuracy.
When the function generator’s output is loaded with a 0.2% accuracy
termination, an additional (negligible) 0.2% amplitude error is created.
Using a 5% accuracy termination will add 5% additional error to
specified output amplitudes.
If the function generator’s output is measured with no load connected,
the output will be approximately twice the displayed amplitude
(V
gen instead of Vload). In some applications, you might continually use
the function generator in a “no-load” conditions. In such applications,
remembering to double the function generator’s displayed amplitude can
cause many errors. The 33120A allows you to specify the function
generator’s load condition using the OUTPUT:LOAD command; thus
enabling the function generator to display the correct output amplitude.
50
W
50
W
Vload
Vgen
7
Chapter 7 Tutorial
Output Amplitude Control
281
To Next Page
Loading...
Need help?
General
