PA Intermodulation Distortion Measurements Using the PNA María Jesús Cañavate Sánchez
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PA Intermodulation Distortion Measurements Using the PNA
María Jesús Cañavate Sánchez
Index
Galashiels
Orkney
1. Introduction: characterization of a power amplifier
2. PNA N5225A
3. S-Parameters
4. AM/AM
5. AM/PM
6. Two-tone test
1. Introduction: characterization of a power amplifier
Galashiels
Orkney
S-Parameters
DUT: Amplifier
1. Introduction: characterization of a power amplifier
Galashiels
Orkney
Nonlinear characteristic
AM/AM and AM/PM compression
of a typical Traveling Wave Tube
(TWT) amplifier.
1. Introduction: characterization of a power amplifier
Galashiels
Orkney
Intermodulation distortion
DUT: Amplifier
Frequency spectrum of the amplifier
input signal: 5 unmodulated carriers.
AM/AM and AM/PM compression
of a typical Traveling Wave Tube
(TWT) amplifier.
Frequency spectrum of the amplifier
output signal: 5 unmodulated
carriers and IMP3.
2. PNA N5225A
Galashiels
Orkney
- Number of ports: 4
- Frequency range: 10MHz – 50GHz
- Max. port power, 20GHz: +13dBm
- Receiver damage level: +15dBm
2. PNA N5225A
Galashiels
Orkney
Damage: +15dBm
Damage: +30dBm
Damage: +43dBm
Coupling factor: 15dB
3. S-Parameters
Galashiels
Orkney
Power flow analysis (for all types of PA measurements)
3. S-Parameters
Galashiels
Orkney
Before calibration: make sure settings are at desired levels
3. S-Parameters
Galashiels
Orkney
Select power and internal attenuators levels
- Output power: -10 dBm
- Gain: 26 dB
- External attenuation: 6 dB
- Internal attenuation: 15 dB
- Measured S21 drops by the attenuation
- After calibration, attenuator losses will
be removed
- Before calibration: Gain = 5 dB
- After calibration: Gain = 26 dB
- Internal attenuation still not available
3. S-Parameters
Galashiels
Orkney
Calibration performance (for all types of PA measurements)
Source–power calibration at the input point of the amplifier
To ensure a constant and known power
Material needed: power sensor
Two-port SOLT calibration
To remove effects of the external and internal attenuators
Material needed: mechanical calibration kit
SOLT: short-open-load-through
3. S-Parameters
Galashiels
Orkney
Calibration performance
Source–power calibration Two-port calibration
3. S-Parameters
Galashiels
Orkney
Measurements
4. AM/AM
Galashiels
Orkney
S21 measurement under a power sweep condition
- Attenuator settings are fixed
- Source-power calibration at
source and receiver ports
4. AM/AM
Galashiels
Orkney
S21 measurement example
Gain
AM/AM
5. AM/PM
Galashiels
Orkney
Procedure:
S21 measurement under a power sweep condition
(AM/AM).
Change the S21 measurement from log magnitude format
to phase format.
No new calibration is required.
6. Two-tone test
Galashiels
Orkney
2 different configurations (option 087):
Using internal PNA components
Only extra cables are required
Using external components
Combiner
Coupler
Extra cables
6. Two-tone test
Galashiels
Orkney
Using internal PNA components:
6. Two-tone test
Galashiels
Orkney
Using external components:
6. Two-tone test
Galashiels
Orkney
6. Two-tone test
Galashiels
Orkney
Frequency tab:
6. Two-tone test
Galashiels
Orkney
Power tab:
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