Keysight EXG and MXG X-Series Signal Generators User’s Guide 117
Optimizing Performance for All Models
Using External Leveling (N5173B/83B Only)
Option 1E1 Output Attenuator Behavior and Use
When using the internal detector, the Option 1E1 output attenuator enables signal generator
power levels down to -130 dBm at the RF Output connector. It accomplishes this by adding
attenuation to the output signal after the ALC detection circuit. The output power value (shown in
the Amplitude area of the display) is the resultant of the Set Atten and Set ALC Level values (see
page 114). With the external detector selected, the output attenuator no longer attenuates the
output signal since the feedback for the detection circuit has been moved beyond the output
attenuator. Because the attenuator no longer affects the amplitude of the output signal, the output
amplitude is determined by only the Set ALC Level softkey.
With external leveling selected, the signal generator enables attenuator hold and the power range
approximates the range of a standard option (no attenuator) signal generator (see the Data Sheet).
As stated earlier, the actual output power may vary due to the external detector and the
coupler/power splitter performance characteristics.
Even though the output attenuator no longer affects the output power, it is still useful to drive the
ALC circuit to its mid–power point of approximately 0 dBm, which is optimal for the internal leveling
circuitry and typically provides the best amplitude flatness results. This is useful with power values
of -5 dBm or less. For example, to drive the ALC to approximately mid–power with a -20 dBm
power setting, add 25 dB of attenuation. This sets the ALC circuit to 5 dBm (-20 + 25).
Configure External Leveling
Basic Setup Process
— If working with a single frequency signal, perform Steps 1 through 5.
— If working with multiple frequencies:
a. Perform Steps 1 through 4.
b. Perform a user flatness correction, see “Using Flatness Correction” on page 98.
— If working with a sweep:
a. Perform Steps 1 through 4.
b. Setup the sweep, see “Using Swept Signal Mode (Configuring a Swept Output)” on page 62.
1. Setup the equipment, see “Equipment Setup” on page 118
2. Configure the carrier signal, see “Configuring the Carrier” on page 118
3. Select external leveling, see “Selecting External Leveling” on page 118.
When the internal detector (Internal selection) is reselected, the signal
generator does not turn the attenuator hold off.
If there is too much attenuation, it will drive the ALC circuit too high and
cause the signal generator to go unleveled. Ensure that you decrease the
attenuation as you increase the power level.
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