Third-Order Intermodulation Distortion - Keysight Technologies N9322C User Manual

Functions and Measurements
Making Distortion Measurements

Third-Order Intermodulation Distortion

Remote
Standby
On
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Two- tone, third- order intermodulation distortion is a
common specification in communication systems. When two
signals are present in a non- linear system, they may interact
and create third- order intermodulation distortion (TOI)
products that are located close to the original signals.
System components such as amplifiers and mixers contribute
to the generation of these distortion products.
This example will test a device for third- order
intermodulation through the use of markers. Two sources
are used, one set to 300 MHz and the other to 301 MHz.
1
Connect the equipment as shown in figure below. This
combination of signal generators, low pass filters, and
directional coupler (used as a combiner) results in a
two- tone source with very low intermodulation distortion.
Although the distortion from this setup may be better than
the specified performance of the analyzer, it is useful for
determining the TOI performance of the source/analyzer
combination. After the performance of the source/analyzer
combination has been verified, the device- under- test (DUT)
(for example, an amplifier) would be inserted between the
directional coupler output and the analyzer input.
Signal Generator
FUNCTIONS
N9310A RF Signal Generator 9 kHz - 3.0 GHz
Frequency AM I/ Q Utility Preset
Amplitude FM Sweep File Local
Enter M Pulse Trigger LF Out
7 8 9 MOD
On/ Off
4 5 6
1 2 3
0 ·
RF
On/ Off
LF OUT RF OUT 50
REVERSE PWR
4W MAX 30VDC
RF OUT
300 MHz LOW
PASS FILTER
Signal Generator
FUNCTIONS
N9310A RF Signal Generator 9 kHz - 3.0 GHz
Frequency AM I/ Q Utility Preset
Amplitude FM Sweep File Local
Enter M Pulse Trigger LF Out
7 8 9 MOD
On/ Off
4 5 6
1 2 3
·
0 RF
Remote On/ Off
Standby LF OUT RF OUT 50
On
REVERSE PWR
4W MAX 30VDC
300 MHz LOW
PASS FILTER
Directional Coupler
Spectrum Analyzer
N 9320A SPECTRUM AN ALYZER 9 kHz - 3.0 GHz
Auto BW / Sw eep/
Tune Avg Trig
Local
View / Det/ File/
M arker
Trace Display Print
Save
Peak
MODE Meas M arker
Search
7 8 9
4 5 6
1 2 3 Back
0 · Enter
Rem ote
50V DC M AX
30dBm 1W M AX
Standby TG SOURCE CAL OU T RF IN 50
On
PROBE POWER
50M Hz 10dBm CAT Ⅱ
RF IN