Atec Agilent-8563E - Manual (Page 132)

ESG Family Signal Generators Adjustments
Power Level Accuracy
Calibration Guide 5-35
Power Level Accuracy
Description
This test adjusts both power flatness and power level accuracy. First the power flatness
and accuracy calibration constants are initialized to zero. Then power flatness is measured
with a power meter, and corrected, with the internal attenuator set to 0 dB. The power
meter then measures the RF output over the +13 to –15 dBm dynamic range, and
calibration constants are set to optimize power level accuracy over this range.
For power levels below
−
15 dBm, a vector signal analyzer is used to make relative power
measurements. A low noise amplifier (LNA) and step attenuator are connected in series to
control the absolute power level input to the signal analyzer. For power level settings
≥ −
60 dBm, the step attenuator is set to approximately cancel the gain of the LNA. Below
−
60 dBm, the step attenuator is set to 0 dB, which keeps the signal level well above the
signal analyzer’s noise floor.
Relative measurements are accomplished by setting the DUT amplitude. For example:
The DUT is set to a frequency and the internal step attenuator is set to 0 dB. The signal
analyzer does a peak search, sets the reference level, and sets the marker to delta mode
(0 dB). The DUT internal attenuator is set to 20 dB, and the signal analyzer makes
another measurement. The signal analyzer relative measurement should be - 20 dB. Any
variation from this value is used to set a calibration constant for the 20 dB attenuator
setting at that frequency.
To determine calibration values for internal step attenuator settings below 60 dB, the
signal analyzer makes the 0 dB marker delta measurement with the internal step
attenuator set to 60 dB, and all lower level measurements are made relative to this
reference. The previously measured error for the 60 dB setting is then accounted for in the
measurement.
For frequencies above 2 GHz, an HP/Agilent 8563E signal analyzer is used to downconvert
the frequency to 321.4 MHz.
Required Test Equipment
See page 1-4 for Details on the following:
• HP/Agilent 438A Power Meter
• HP/Agilent 8482A Power Sensor
• HP/Agilent 89441A Vector Signal
Analyzer
• HP/Agilent 8563E Option 001 Signal
Analyzer
• HP/Agilent 8491A/B Option 006 (6dB)
Attenuator
• HP/Agilent 8495G Programmable Step
Attenuator (0 to 70 dB)
• HP/Agilent 11713A Step Attenuator Driver
• Low Frequency Noise Amplifier (LNA) • High Frequency Low Noise Amplifier (LNA)