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Minimum input power 0 dBm
Output bandwidth 1 Hz to 40 MHz
AM Detector Considerations
•
The AM detector consists of an Agilent/HP 33330C Low-Barrier
Schottky Diode Detector and an AM detector filter (Agilent/HP 70429A
K21).
•
The detector, for example, is an Agilent/HP 33330C Low-Barrier
Schottky-Diode Detector. The Schottky detectors will handle more
power than the point contact detectors, and are equally as sensitive and
quiet.
•
The AM detector output blocking capacitor in the Agilent/HP 70429A
Option K21, 70420A Option 001, or 70427A prevents the dc voltage
component of the demodulated signal from saturating the system's low
noise amplifier (LNA). The value of this capacitor sets the lower
frequency limit of the demodulated output.
•
Carrier feedthrough in the detector may be excessive for frequencies
below a few hundred megahertz. The LNA is protected from saturation
by the internal filters used to absorb phase detector feedthrough and
unwanted mixer products. This limits the maximum carrier offset
frequency to:
Table 12-1
•
The ac load on the detector is 50 ohms, set by the input impedance of the
LNA in the test system. The 50 ohm load increases the detector
bandwidth up to than 100 MHz.
•
The Agilent/HP 70420A phase noise test set must be dc blocked when
using its Noise Input or internal AM detector. The test set will not
tolerate more than ± 2 mV DC Input without overloading the LNA. A
DC block must be connected in series after the AM Detector to remove
the dc component. The Agilent/HP 70429A Option K21 is designed
specifically for this purpose or the internal DC blocking filter in either
the Agilent/HP 70420A or Agilent/HP 70427A may be used.
Agilent Technologies E5500 Phase Noise Measurement System 12-5
AM Noise Measurement Fundamentals
Amplitude Noise Measurement
Maximum Carrier Offset Frequency
Carrier Frequency
≥
250 kHz
≥
50 MHz
≥
5 MHz
≥
500 kHz
≥
50 kHz
Offset Frequency
100 MHz
20 MHz
2 MHz
200 kHz
20 kHz
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