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Calibration and Measurement General Guidelines
Read This The following general guidelines should be considered when setting up and
NO T E
making an AM-noise measurement
• The AM detector must be well shielded from external noise especially 60 Hz
The internal detectors in the N5500A Option 001 and N5507A, along with the 70429A
NO T E
Option K21 provide this level of protection.
• Although AM noise measurements are less vulnerable than residual
• The output voltage monitor on the AM detector must be disconnected from
• The noise floor of the detector may degrade as power increases above +15
• An amplifier must be used in cases where the signal level out of the DUT is
• It should have the lowest possible noise figure, and the greatest possible
• The signal level must be kept as high as possible at all points in the test
• It should have only enough gain to get the required signal levels. Excess gain
• The amplifier's sensitivity to power supply noise and the supply noise itself
Agilent E5505A User's Guide
noise. The components between the diode detector and the test system
should be packaged in a metal box to prevent RFI interference.
Also, the AM detector should be connected directly to the test system if
possible, to minimize ground loops. If the AM detector and test system must
be separated, semi-rigid cable should be used to keep the shield resistance
to a minimum.
phase-noise measurements to noise induced by vibration and temperature
fluctuation, care should be taken to ensure that all connections are tight
and that all cables are electrically sound.
digital voltmeters or other noisy monitoring equipment before noise
measurement data is taken.
1
- - -
f
1
- - -
dBm. Noise in the
region of the detector is best measured with about +10
f
dBm of drive level. The noise floor is best measured with about +20 dBm of
drive level.
too small to drive the AM detector or is inadequate to produce a low enough
measurement noise floor. In this case the amplifier should have the
following characteristics.
dynamic range.
setup to avoid noise floor degradation.
leads to amplifiers operating in gain compression, increasing their
likelihood of suppressing the AM noise to be measured.
must both be minimized.
AM Noise Measurement Fundamentals
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