Agilent Technologies PN 8510-16 User Manual
Agilent PN 8510-16
Controlling Test Port Output
Power Flatness
Product Note
UNCORRECTED POWER
CORRECTED POWER
OUTPUT POWER
Agilent 8510C Network Analyzer
2
Introduction
Designers and manufacturers of active devices
often need to control the power level at the test
port1of their power-sensitive devices, but find difficulty in overcoming insertion losses. The insertion
losses occur as a result of connecting components
in the measurement path between the source and
the DUT. The Agilent Technologies 8510C is a
microwave network analyzer2capable of setting
and controlling the power level at the test port.
This product note reviews the implementation
and operational considerations of the 8510C’s
test port power flatness-correction feature.
The 8510C performs a flatness-correction calibration by measuring the test port power level
using an Agilent power meter and creates a table
of power corrections versus frequency. The
power meter then stores the table into an Agilent
8360 series synthesized sweeper.3When the test
port flatness correction is enabled, the source
will adjust its output power to compensate for
path losses at each measurement point in the
frequency span.
1. In this document, “test port” will refer to the point in the system where the test
device is connected. This may be port 1 or port 2 of any 8510 coaxial-based test
set or the end of a cable or adapter that is attached to the DUT.
2. 8510B network analyzers with revision B.06 or later may also be used to achieve
constant test port power levels. To obtain the latest firmware revision order the
11575F upgrade kit.
3. Any 8360 synthesized sweeper with firmware revision of September 25, 1990 or
earlier must be upgraded. To upgrade your 8360 to the latest firmware revision,
order part number 08360-60167.
Power flatness correction is useful for characterizing active devices by allowing measurements of
absolute power, gain versus input power, and
swept-frequency gain compression. Swept-power
gain compression measurements are possible in
the power domain with the flatness correction
enabled.
The 8510XF measurement system is capable of leveling and controlling the test port power between
45 MHz and 110 GHz without requiring a power
calibration for each measurement. When power leveling is enabled, the test port power variation is
typically less than ±1 dB over the full frequency
sweep, with 20 dB of adjustable power. For more
information regarding power leveling in the Agilent
8510XF, refer to product note 8510XF-1, literature
number 5968-5270E.
3
System Configuration
The basic 8510C measurement system configuration needed for test port f latness correction is
shown in Figure 1. A single channel power meter
such as the Agilent 437B, E4418A, or E4418B is
required, along with a compatible sensor, for performing the power flatness calibration. Power
meters with the 437B command set must be used
for the power level flatness correction.
Figure 1. Basic Agilent 85107B measurement system configuration for test port flatness correction
The Agilent 8511B frequency converter test
set may be used with the test port power flatnesscorrection feature. The range of the test port
power is determined by the available power of
the 8360 source and the insertion loss of the components added to the measurement system.
8517B test set
8485A
power sensor
E4418B
power meter
83651B
synthesized sweeper
8510 system bus
85107B Measurement System
8510C network analyzer
4
Flatness-Correction Operation
The basic setup procedure to obtain flat test port
output power is illustrated in Table 1. To simplify
the execution of the procedure, the front panel
hardkeys are enclosed in [brackets]. The softkeys
are enclosed in {braces}. Table 2 provides the procedure for setting up the power meter. The network analyzer should be reset before performing
any procedures. The flatness-correction calibration
can be performed in step, ramp, or frequency list
sweep mode. Figure 2 illustrates test port power
versus frequency with and without f latness correction using an 85107B measurement system.
When the flatness correction is enabled in an
8510C measurement system the analyzer’s Power
Source 1 softkey controls the test port power level.
The source and test set used will determine the
available test port power range.
The maximum leveled power the source can output at different frequency spans is indicated in
Table 3. Once the flatness correction is enabled,
the test port power level must be set within the
power range presented in Table 4 for common
source/test set combinations.
Figure 2. Comparison of test port power without flatness correction (channel 1)
and with flatness correction (channel 2)
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