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Network Analysis
Back to Basics
Objectives
Review RF basics (transmission lines, etc.)
Understand what types of measurements are made with vector
network analyzers (VNAs)
Examine architectures of modern VNAs
Provide insight into nonlinear
characterization of amplifiers,
mixers, and converters using a VNA
Understand associated calibrations
Application: Amplifiers test and Fixture
Simulator
Automation VBA example
Network Analysis is NOT.…
Router
Bridge
Repeater
Hub
Your IEEE 802.37 X.25 ASDN switched-packet data stream is running at 547 MBPS with a BER of 1.523 X 10 . . .
-9
What Are Vector Network Analyzers?
Are stimulus-response test systems
Characterize forward and reverse reflection and transmission responses (S-parameters) of RF and microwave components
Quantify linear magnitude and phase
Are very fast for swept measurements
Provide the highest level of measurement accuracy
S21
S12
S11 S22
R1 R2
RF Source
LO
Test port 2
B A
Test port 1
Phase
Magnitude
DUT
Reflection
Transmission
What Types of Devices are Tested?
Device type Active Passive
Inte
gra
tio
n
Hig
h
Lo
w
Antennas
Switches
Multiplexers
Mixers
Samplers
Multipliers
Diodes
Duplexers
Diplexers
Filters
Couplers
Bridges
Splitters, dividers
Combiners
Isolators
Circulators
Attenuators
Adapters
Opens, shorts, loads
Delay lines
Cables
Transmission lines
Resonators
Dielectrics
R, L, C's
RFICs
MMICs
T/R modules
Transceivers
Receivers
Tuners
Converters
VCAs
Amplifiers
VTFs
Modulators
VCAtten’s
Transistors
Device Test Measurement Model
NF
Stimulus type Complex Simple
Co
mp
lex
Re
sp
on
se
to
ol
Sim
ple
DC CW Swept Swept Noise 2-tone Multi-tone Complex Pulsed- Protocol freq power modulation RF
Det/Scope
Param. An.
NF Mtr.
Imped. An.
Power Mtr.
SNA
VNA
SA
VSA
RFIC Testers
TG/SA
Ded. Testers
I-V
Absol.
Power
LCR/Z
Harm. Dist.
LO stability
Image Rej.
Gain/flat.
Phase/GD
Isolation
Rtn loss
Impedance
S-parameters
Compr'n
AM-PM
Mixers
Balance
d
RFIC test
Full call
sequence
Pulsed S-parm.
Pulse profiling
BER
EVM
ACP
Regrowth
Constell.
Eye
Intermodulation
Distortion NF
Measurement plane
Lightwave Analogy to RF Energy
RF
Incident
Reflected
Transmitted
Lightwave
DUT
Why Do We Need to Test Components?
Verify specifications of “building blocks”
for more complex RF systems
Ensure distortionless transmission
of communications signals
• Linear: constant amplitude, linear phase / constant group delay
• Nonlinear: harmonics, intermodulation, compression, X-parameters
Ensure good match when absorbing
power (e.g., an antenna)
KPWR FM 97
The Need for Both Magnitude and Phase
4. Time-domain characterization
Mag
Time
5. Vector-error correction
Error
Measured
Actual
2. Complex impedance
needed to design
matching circuits
3. Complex values
needed for device
modeling
1. Complete characterization
of linear networks
S21
S12
S11 S22
6. X-parameter (nonlinear) characterization
Agenda
• What measurements do we make?
• Network analyzer hardware
• Error models and calibration
• Applications
• Automation RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
SHORT
OPEN
LOAD
Transmission Line Basics
Low frequencies Wavelengths >> wire length
Current (I) travels down wires easily for efficient power transmission
Measured voltage and current not dependent on position along wire
High frequencies
Wavelength or << length of transmission medium
Need transmission lines for efficient power transmission
Matching to characteristic impedance (Zo) is very important for
low reflection and maximum power transfer
Measured envelope voltage dependent on position along line
+ _
I
Transmission line Zo
Zo determines relationship between voltage and current waves
Zo is a function of physical dimensions and r
Zo is usually a real impedance (e.g. 50 or 75 ohms)
Characteristic impedance for coaxial
airlines (ohms)
10 20 30 40 50 60 70 80 90 100
1.0
0.8
0.7
0.6
0.5
0.9
1.5
1.4
1.3
1.2
1.1
norm
aliz
ed v
alu
es
50 ohm standard
attenuation is
lowest at 77 ohms
power handling capacity
peaks at 30 ohms
Power Transfer Efficiency
RS
RL
For complex impedances, maximum
power transfer occurs when ZL = ZS*
(conjugate match)
Maximum power is transferred when RL = RS
RL / RS
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
Lo
ad
Po
we
r
(no
rma
lized
)
Rs
RL
+jX
-jX
Transmission Line Terminated with Zo
For reflection, a transmission line terminated in Zo
behaves like an infinitely long transmission line
Zs = Zo
Zo
Vreflect = 0! (all the incident power
is transferred to and
absorbed in the load)
V inc
Zo = characteristic impedance
of transmission line
Transmission Line Terminated with Short, Open
Zs = Zo
Vreflect
V inc
For reflection, a transmission line terminated in a
short or open reflects all power back to source
In-phase (0o) for open,
out-of-phase (180o) for short
Transmission Line Terminated with 25 Ohms
Vreflect
Standing wave pattern does not
go to zero as with short or open
Zs = Zo
ZL = 25 W
V inc
High-Frequency Device Characterization
Transmitted
Incident
TRANSMISSION
Gain / Loss
S-Parameters
S21, S12
Group
Delay
Transmission
Coefficient
Insertion
Phase
Reflected
Incident
REFLECTION
VSW
R
S-Parameters
S11, S22 Reflection
Coefficient
Impedance,
Admittance
R+jX,
G+jB
Return Loss
G, r T,t
Incident
Reflected
Transmitted R B
A
A
R =
B
R =
Reflection Parameters
dB
No reflection
(ZL = Zo)
r
RL
VSWR
0 1
Full reflection
(ZL = open, short)
0 dB
1
= Reflection
Coefficient =
V reflected
V incident
= r F G
= r G Return loss = -20 log(r ),
Voltage Standing Wave
Ratio
VSWR = Vmax
Vmin =
1 + r
1 - r
Vmax
Vmin
ZL - Zo
ZL + Zo
Smith Chart Review
Smith Chart maps
rectilinear impedance
plane onto polar plane
0 +R
+jX
-jX
Rectilinear impedance plane -90 o
0 o 180
o + -
.2
.4
.6
.8
1.0
90 o
0
Polar plane
Z = Zo L
= 0 G
Constant X
Constant R
Smith chart
G L
Z = 0
= ±180 O
1
(short) Z = L
= 0 O
1 G
(open)
Transmission Parameters
V Transmitted
V Incident
Transmission Coefficient = T = V Transmitted
V Incident
= t
DUT
Gain (dB) = 20 Log V
Trans
V Inc
Insertion Loss (dB) = -20 Log V
Trans
V Inc
= -20 Log(t)
= 20 Log(t)
Linear Versus Nonlinear Behavior
Linear behavior: Input and output frequencies are the
same (no additional frequencies created)
Output frequency only undergoes
magnitude and phase change
Frequency f 1
Time
Sin 360o * f * t
Frequency
A phase shift =
to * 360o * f
1 f
DUT
Time
A
t o
A * Sin 360o * f (t - to)
Input Output
Time
Nonlinear behavior: Output frequency may undergo
frequency shift (e.g. with mixers)
Additional frequencies created
(harmonics, intermodulation)
Frequency f 1
Criteria for Distortionless Transmission
Constant amplitude over
bandwidth of interest
Magnitude
Phase
Frequency
Frequency
Linear phase over
bandwidth of
interest
Linear Networks
Magnitude Variation with Frequency
F(t) = sin wt + 1/3 sin 3wt + 1/5 sin 5wt
Time
Linear Network
Frequency Frequency Frequency
Magnitude
Time
Phase Variation with Frequency
Frequency
Magnitude
Linear Network
Frequency
Frequency
Time
0
-180
-360
°
°
°
Time
F(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wt
Deviation from Linear Phase
Use electrical delay to remove
linear portion of phase response Linear electrical length
added
+ =
Frequency
(Electrical delay function)
Frequency
RF filter response Deviation from linear
phase
Ph
ase
1
/Div
o
Ph
ase
45
/D
iv
o
Frequency
Low resolution High resolution
Group Delay
in radians
in radians/sec
in degrees
f in Hertz (w = 2 p f)
w
Group Delay (tg) =
-d d w
= -1
360 o
d d f *
Frequency
Group delay ripple
Average delay
t o
t g
Phase
D
Frequency (w)
Dw
Group-delay ripple indicates phase distortion
Average delay indicates electrical length of DUT
Aperture (Dw) of measurement is very important
Why Measure Group Delay?
Same peak-peak phase ripple can result in different group delay
Ph
ase
Ph
ase
Gro
up
De
lay
Gro
up
De
lay
-d d w
-d d w
f
f
f
f
Characterizing Unknown Devices
Using parameters (H, Y, Z, S) to characterize devices:
Gives linear behavioral model of our device
Measure parameters (e.g. voltage and current) versus frequency under
various source and load conditions (e.g. short and open circuits)
Compute device parameters from measured data
Predict circuit performance under any source and load conditions
H-parameters
V1 = h11I1 + h12V2
I2 = h21I1 + h22V2
Y-parameters
I1 = y11V1 + y12V2
I2 = y21V1 + y22V2
Z-parameters
V1 = z11I1 + z12I2
V2 = z21I1 + z22I2
h11 = V1
I1 V2=0
h12 = V1
V2 I1=0
(requires short circuit)
(requires open circuit)
Why Use S-Parameters?
Relatively easy to obtain at high frequencies
Measure voltage traveling waves with a vector network analyzer
Don't need shorts/opens (can cause active devices to oscillate or self-destruct)
Relate to familiar measurements (gain, loss, reflection coefficient ...)
Can cascade S-parameters of multiple devices to predict system performance
Can compute H-, Y-, or Z-parameters from S-parameters if desired
Can easily import and use S-parameter files in electronic-simulation tools
Incident Transmitted S 21
S 11 Reflected S 22
Reflected
Transmitted Incident
b 1
a 1 b 2
a 2 S 12
DUT
b 1 = S 11 a 1 + S 12 a 2
b 2 = S 21 a 1 + S 22 a 2
Port 1 Port 2
Measuring S-Parameters
S 22 = Reflected
Incident =
b 2
a 2 a 1 = 0
S 12 = Transmitted
Incident =
b 1
a 2 a 1 = 0
S 11 = Reflected
Incident =
b 1
a 1 a 2 = 0
S 21 = Transmitted
Incident =
b 2
a 1 a 2 = 0
Incident Transmitted S 21
S 11
Reflected b
a 1
b 2
1
Z 0
Load
a 2 = 0
DUT Forward
Incident Transmitted S 12
S 22
Reflected
b 2
a 2
b
a 1 = 0
DUT Z 0
Load Reverse
1
Equating S-Parameters With
Common Measurement Terms
S11 = forward reflection coefficient (input match)
S22 = reverse reflection coefficient (output match)
S21 = forward transmission coefficient (gain or loss)
S12 = reverse transmission coefficient (isolation)
Remember, S-parameters are inherently
complex, linear quantities -- however, we often
express them in a log-magnitude format
Measurements on Nonlinear Components
• Saturation, crossover, intermodulation, and other nonlinear
effects can cause signal distortion
• Effect on system depends on amount and type of distortion
and system architecture
Nonlinear Networks
33
Scattering Parameters – Power Dependence
An early attempt at providing
some power-dependence
was the P2D files used in
ADS.
Unfortunately these files did
not properly capture non-
linear behavior except S11
and S21 compression,
nor did they predict
harmonics and IMD
34
X-parameters come from the
Poly-Harmonic Distortion (PHD) Framework
1 1 11 12 21 22( , , ,..., , ,...)k kB F DC A A A A=
2 2 11 12 21 22( , , ,..., , ,...)k kB F DC A A A A=Port Index Harmonic (or carrier) Index
Spectral map of complex large input phasors to large complex output phasors Black-Box description holds for transistors, amplifiers, RF systems, etc.
2A1A
1B
37
X-parameters Reduce to S-parameters
11
( )
21 11 21| | 0
[ ( )] F
A
X A s
11
( )
21,21 11| | 0
( ) 0T
AX A
-60 -25 -20 -15 -10 -5 0 5 10
|A11| (dBm)
-40
40
20
0
-20
dB
( )
21,21
SX
( )
21,21
TX
( )
21 11/ | |FX A
Reduces to (linear)
S-parameters in the
appropriate limit
11
( )
21,21 11 22| | 0
( )S
AX A s
+
11| |A
( )
21 1
( )
21,21
2 *
21 11
( )
21,21 11 21 1 11 21() )( ) ( )( TF SXB XA A P AAAA XP= + +
Agenda
• What measurements do we make?
• Network analyzer hardware
• Error models and calibration
• Applications
• Automation RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
SHORT
OPEN
LOAD
Generalized Network Analyzer Block Diagram
(Forward Measurements Shown)
RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B)
INCIDENT
(R)
SIGNAL
SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
Source
Supplies stimulus for system
Can sweep frequency or power
Traditionally NAs had one signal source
Modern NAs have the option for a second
internal source and/or the ability to control
external source.
Can control an external source as a local
oscillator (LO) signal for mixers and
converters
Useful for mixer measurements like
conversion loss, group delay
RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL
SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
Signal Separation
Test Port
Detector directional
coupler
splitter bridge
• Measure incident signal for reference
• Separate incident and reflected signals RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL
SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
Directivity
Directivity is a measure of how well a directional coupler or
bridge can separate signals moving in opposite directions
Test port
(undesired leakage
signal) (desired reflected
signal)
Directional Coupler
desired leakage
result
Directivity = Isolation (I) - Fwd Coupling (C) - Main Arm Loss (L)
I C
L
Directional Bridge
Test Port
Detector
50 W 50 W
50 W
50-ohm load at test port balances
the bridge -- detector reads zero
Non-50-ohm load imbalances bridge
Measuring magnitude and phase of
imbalance gives complex impedance
"Directivity" is difference between
maximum and minimum balance
Advantage: less loss at low
frequencies
Disadvantages: more loss in main
arm at high frequencies and less
power-handling capability
Interaction of Directivity with the DUT
(Without Error Correction)
Data max
Add in-phase
Device
Directivity
Retu
rn L
oss
Frequency
0
30
60
DUT RL = 40 dB
Add out-of-phase
(cancellation)
De
vic
e
Directivity
Data = vector sum
Dire
ctivity
Devic
e Data min
Detector Types:
Narrowband Detection - Tuned Receiver
Best sensitivity / dynamic range
Provides harmonic / spurious signal rejection
Improve dynamic range by increasing power,
decreasing IF bandwidth, or averaging
Trade off noise floor and measurement speed
10 MHz 26.5 GHz
IF Filter
LO
ADC / DSP RF
RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL
SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT Tuned Receiver Front Ends:
Mixers Versus Samplers
It is cheaper and easier to make
broadband front ends using
samplers instead of mixers, but
dynamic range is considerably less
Mixer-based front end
ADC / DSP
Sampler-based front end
S
Harmonic
generator
f
frequency "comb"
ADC / DSP
Error Due to Interfering Signal
0.001
0.01
0.1
1
10
100
0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70
Interfering signal or noise (dB)
Err
or
(dB
, d
eg) phase error
magn error
+
-
Dynamic range is
very important for
measurement
accuracy!
Dynamic Range and Accuracy
T/R Versus S-Parameter Test Sets
RF comes out port 1; port 2 is receiver
Forward measurements only
Response, one-port cal available
RF comes out port 1 or port 2
Forward and reverse measurements
Two-port calibration possible
Transmission/Reflection Test Set
Port 1 Port 2
Source
B
R
A
DUT Fwd
S-Parameter Test Set
DUT Fwd Rev
Port 1
Transfer switch
Port 2
Source
B
R1
A
R2
Fwd
Modern VNA Block Diagram (2-Port PNA-X)
DUT
Test port 1
R1
Test port 2
R2
A B
To receivers
LO
Source 2
Output 1
Source 2
Output 2
Pulse generators
rear panel
1
2
3
4
+28V
Noise receivers
10 MHz -
3 GHz
3 –
13.5/
26.5
GHz
Source 1
OUT 1 OUT 2
Pulse
modulator
Source 2
OUT 1 OUT 2
Pulse
modulator
RF jumpers
S-parameter receivers
Mechanical switch noise receivers
J9 J10 J11 J8 J7 J2 J1
Impedance tuner for noise
figure measurements
+
-
RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B)
INCIDENT
(R)
SIGNAL
SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
Processor / Display
• Markers
• Limit lines
• Pass/fail indicators
• Linear/log formats
• Grid/polar/Smith charts
• Time-domain transform
• Trace math
Achieving Measurement Flexibility
Channel
Trace Trace Trace Trace Trace Trace
Trace
• Parameter
• Format
• Scale
• Markers
• Trace math
• Electrical delay
• Phase offset
• Smoothing
• Limit tests
• Time-domain transform
Channel
• Sweep type
• Frequencies
• Power level
• IF bandwidth
• Number of points
• Trigger state
• Averaging
• Calibration
Window Window
Window Window
Trace (CH1)
Trace (CH2)
Trace (CH1)
Trace (CH2) Trace (CH3)
Trace (CH4)
Three Channel Example
Window
Window Window
Channel 1
frequency sweep (narrow)
S11 S21
Channel 2
frequency sweep (broad)
S21
Channel 3
power sweep
S21 S11
Agenda
• What measurements do we make?
• Network analyzer hardware
• Error models and calibration
• Applications
• Automation RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
SHORT
OPEN
LOAD
The Need For Calibration
Why do we have to calibrate?
• It is impossible to make perfect hardware
• It would be extremely difficult and expensive to make hardware good
enough to entirely eliminate the need for error correction
How do we get accuracy?
• With vector-error-corrected calibration
• Not the same as the yearly instrument calibration
What does calibration do for us?
• Removes the largest contributor to measurement
uncertainty: systematic errors
• Provides best picture of true performance of DUT Systematic error
Measurement Error Modeling
Systematic errors
• Due to imperfections in the analyzer and test setup
• Assumed to be time invariant (predictable)
• Generally, are largest sources or error
Random errors
• Vary with time in random fashion (unpredictable)
• Main contributors: instrument noise, switch and connector repeatability
Drift errors
• Due to system performance changing after a calibration has been done
• Primarily caused by temperature variation
Measured
Data
SYSTEMATIC
RANDOM
DRIFT
Errors:
Unknown
Device
Systematic Measurement Errors
A B
Source
Mismatch
Load
Mismatch
Crosstalk Directivity
DUT
Frequency response
Reflection tracking (A/R)
Transmission tracking (B/R)
R
Six forward and six reverse error terms
yields 12 error terms for two-port devices
What is Vector-Error Correction?
Vector-error correction…
• Is a process for characterizing systematic error terms
• Measures known electrical standards
• Removes effects of error terms from subsequent measurements
Electrical standards…
• Can be mechanical or electronic
• Are often an open, short, load, and thru,
but can be arbitrary impedances as well
Errors
Measured
Actual
Using Known Standards to Correct
for Systematic Errors
1-port calibration (reflection measurements)
Only three systematic error terms measured
Directivity, source match, and reflection tracking
Full two-port calibration (reflection and transmission measurements)
Twelve systematic error terms measured
Usually requires 12 measurements on four known standards (SOLT)
Standards defined in cal kit definition file
Network analyzer contains standard cal kit definitions
CAL KIT DEFINITION MUST MATCH ACTUAL CAL KIT USED!
User-built standards must be characterized and entered into user cal-kit
Reflection: One-Port Model
ED = Directivity
ERT = Reflection tracking
ES = Source Match
S11M = Measured
S11A = Actual
To solve for error terms, we
measure 3 standards to generate
3 equations and 3 unknowns
S11M
S11A ES
ERT
ED
1 RF in
Error Adapter
S11M
S11A
RF in Ideal
Assumes good termination at port two if testing two-port devices
If using port two of NA and DUT reverse isolation is low (e.g., filter passband):
Assumption of good termination is not valid
Two-port error correction yields better results
S11M = ED + ERT
1 - ES S11A
S11A
Before and After A One-Port Calibration
Data before 1-port calibration
Data after 1-port calibration
Two-Port Error Correction
Each actual S-parameter is a function of
all four measured S-parameters
Analyzer must make forward and reverse
sweep to update any one S-parameter
Luckily, you don't need to know these
equations to use a network analyzers!!!
Port 1 Port 2 E
S 11
S 21
S 12
S 22
E S E D
E RT
E TT
E L
a 1
b 1
A
A
A
A
X
a 2
b 2
Forward model
= fwd directivity
= fwd source match
= fwd reflection tracking
= fwd load match
= fwd transmission tracking
= fwd isolation
E S
E D
E RT
E TT
E L
E X
= rev reflection tracking
= rev transmission tracking
= rev directivity
= rev source match
= rev load match
= rev isolation
E S'
E D'
E RT'
E TT'
E L'
E X'
Port 1 Port 2
S 11
S
S 12
S 22 E S' E D'
E RT'
E TT'
E L'
a 1
b 1 A
A
A
E X'
21 A
a 2
b 2
Reverse model
S a
S m ED
ERT
S m ED
ERT
ES E L
S m E X
ETT
S m E X
ETT
S m ED'
ERT
ES
S m ED
ERT
ES E L EL
S m E X
ETT
S m E X
ETT
11
111
22 21 12
111
122 21 12
=
-+
--
- -
+-
+-
-- -
( )('
'' ) ( )(
'
')
( )('
'' ) ' ( )(
'
')
S a
S m E X
ETT
S m ED
ERT
ES EL
S m ED
ERT
ES
S m ED
ERT
ES EL
21
21 22
111
122
=
-1 +
--
+-
+-
-
( )('
'( ' ))
( )('
'' ) ' ( )(
'
')EL
S m E X
ETT
S m E X
ETT
21 12- -
'S E S E- -(
')( ( ' ))
( )('
'' ) ' ( )(
'
')
m X
ETT
m D
ERT
ES EL
S m ED
ERT
ES
S m ED
ERT
ES EL E L
S m E X
ETT
S m E X
ETT
S a
121
11
111
122 21 12
12
+ -
+-
+-
-- -
=
('
')(
(
S m ED
ERT
S m ED
ERT
S a
22
111
22
-) ' ( )(
'
')
S m ED
ERT
ES EL
S m E X
ETT
S m E X
ETT
11 21 12--
- -
+-
=
ES
S m ED
ERT
ES EL EL
S m E X
ETT
S m E X
ETT
)('
'' ) ' ( )(
'
')1
22 21 12+
--
- -
1 +
Crosstalk: Signal Leakage Between Test Ports
During Transmission
Can be a problem with:
• High-isolation devices (e.g., switch in open position)
• High-dynamic range devices (some filter stopbands)
Isolation calibration
• Adds noise to error model (measuring near noise floor of system)
• Only perform if really needed (use averaging if necessary)
• If crosstalk is independent of DUT match, use two terminations
• If dependent on DUT match, use two
DUTs with termination on output
DUT
DUT LOAD DUT LOAD
Errors and Calibration Standards
Convenient
Generally not accurate
No errors removed
Easy to perform
Use when highest
accuracy is not
required
Removes frequency
response error
For reflection measurements
Need good termination for
high accuracy with two-port
devices
Removes these errors:
Directivity
Source match
Reflection tracking
Highest accuracy
Removes these
errors:
Directivity
Source, load match
Reflection tracking
Transmission
tracking
Crosstalk
UNCORRECTED RESPONSE 1-PORT
FULL 2-PORT
DUT
DUT
DUT
DUT
thru
thru
ENHANCED-RESPONSE
Combines response and 1-port
Corrects source match for transmission
measurements
SHORT
OPEN
LOAD
SHORT
OPEN
LOAD
SHORT
OPEN
LOAD
Calibration Summary
error cannot be corrected
* enhanced response cal corrects
for source match during
transmission measurements
error can be corrected
SHORT
OPEN
LOAD Reflection tracking
Directivity
Source match
Load match
S-parameter (two-port)
T/R (one-port)
Reflection Test Set (cal type)
Transmission Tracking
Crosstalk
Source match
Load match
S-parameter (two-port)
T/R
(response, isolation) Transmission
Test Set (cal type)
* ( )
Response versus Two-Port Calibration
Uncorrected
After two-port calibration
After response calibration
Measuring filter insertion loss
• Variety of two- and four-port modules cover 300 kHz to 67 GHz
• Nine connector types available, 50 and 75 ohms
• Single-connection calibration
dramatically reduces calibration time
makes calibrations easy to perform
minimizes wear on cables and standards
eliminates operator errors
• Highly repeatable temperature-compensated
characterized terminations provide excellent accuracy
ECal: Electronic Calibration
Microwave modules use a
transmission line shunted
by PIN-diode switches in
various combinations
USB controlled
ECAL User Characterizations
4. VNA stores resulting
characterization data
inside the module.
2. Perform a calibration
using appropriate
mechanical standards.
3. Measure the ECal
module, including
adapters, as though
it were a DUT
1. Select adapters for the
module to match the
connector configuration
of the DUT.
Thru-Reflect-Line (TRL) Calibration
We know about Short-Open-Load-Thru (SOLT) calibration... What is TRL?
A two-port calibration technique
Good for non-coaxial environments (waveguide, fixtures, wafer probing)
Characterizes same 12 systematic errors as the more common SOLT cal
Uses practical calibration standards that
are easily fabricated and characterized
Other variations: Line-Reflect-Match (LRM),
Thru-Reflect-Match (TRM), plus many others
TRL was developed for
non-coaxial microwave
measurements
Network Analyzer Basics
www.agilent.com/find/backtobasics
Unknown-Thru Calibration
Cal Methods are listed in order of
ascending accuracy (least accurate
first):
• Uncharacterized Thru Adapter
• Electronic Calibrator (Ecal)
• Ecal with Unknown Thru
• Mechanical with Unknown Thru
Cal
• Adapter Removal
Analyzer
Port 1 Port 2
Thru Short
Open
Load
Short
Open
Load
DUT
Analyzer
Port 1 Port 2 DUT
Agenda
• What measurements do we make?
• Network analyzer hardware
• Error models and calibration
• Applications
• Automation RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
SHORT
OPEN
LOAD
76
VNA application examples
– RF amplifier test
– High-power measurement
76
RF amplifier test
The modern VNA is a more suited solution for many parametric tests of RF amplifiers.
Gain compression Sweeps both frequency and
input power level at PxdB
Harmonic Distortion Performs real-time harmonics test
over frequency or input power
Efficiency (PAE) Calculate power-added
efficiency (PAE)
Swept IMD Performs IMD analysis over an
entire range of frequencies
High-power test Performs accurate tests with
high-power input / output of DUT
VNA
Pulsed-RF Characterize pulsed
performance of devices
Stability (K-factor) Calculates stability (K-factor)
from all S-parameters with
equation editor
f1 f2 f3 f1
77
78
What is gain compression?
•Parameter to define the transition between the linear and nonlinear region of an active device.
•The compression point is observed as x dB drop in the gain with VNA’s power sweep.
Output Power (dBm)
Input Power (dBm)
Linear region
Compression
(nonlinear) region
Power is not high enough
to compress DUT.
Gain (S21)
Input Power (dBm)
Sufficient power
level to drive DUT
Enough margin of source power capability
is needed for analyzers.
DUT
78
Modern VNA (Agilent E5072A)
VNA Functions Power sweep range
Legacy VNA (Agilent/ HP 8753ES)
Ex.) RF amplifier - Gain compression point
• Power sweep range is limited within 25 dB
(i.e. -15 to 10 dBm).
• VNA’s output power is NOT high enough to
see compression point of DUT.
• VNA can drive up to +20 dBm, enough to
detect compression point.
8753’s sweep range
(i.e. -15 to +10 dBm)
:
•Wide power sweep range (>65 dB) enables
linear and nonlinear test with a single sweep.
S21
S21
79
DUT
VNA Functions User Interface
Legacy VNA
• Measurement wizard is provided using the VNA’s
built-in automated software environment (i.e. VBA;
Visual Basic for Applications)
• Easy setup for calibration / measurement.
• No external system controller is necessary.
• Manual parameter setup only.
• Customers need to develop their own
software for applications.
Modern VNA
System Controller
80
VNA Functions
Measurement Wizard • Measurement wizard program speeds up measurements of RF amplifiers. • Key parameters of amplifiers: S-parameters, harmonics distortion, gain compression (CW or
Swept frequency), and swept-frequency IMD measurements. • Can be downloaded from www.agilent.com/find/enavba
81
82
VNA application examples
– RF amplifier test
– High-power measurement
82
83
Why high-power measurements?
Diagram of RF interface in wireless communication
Antenna
Rx Filter
Power Amp
Tx Filter
LNA
Duplexer
Combiner
• Components used for transmitting data in wireless communications
need to be tested with high-power signals under conditions similar
to actual operation. (may be beyond the measurement capability of
instruments!)
83
84
Power (initial)
High-power Measurements
Measurement Challenges:
• Power leveling - Eliminating short-term drift of a booster amplifier’s gain;
variation of input power to DUT.
When temperature changes after setup / calibration,
input power levels are changed even out of tolerance!
Temperature drift of a booster amp needs to be considered.
Configuration with a booster amp
SA SG Booster
amp Pin DUT
System Controller Power (drifted)
Input power (dBm)
Frequency (Hz)
tolerance
Target
power
level
DUT’s actual input power (Pin)
Gain
Gain variation from
temperature drift
84
Power (drifted)
High-power Measurements Power leveling
Measurement Challenges:
• Power leveling process takes very long time!
• Test configuration is complicated; necessary to lower overall cost of test systems.
SG’s power
is adjusted
Configuration for input power leveling
SA DUT SG
Power
Sensor
Coupler
e.g. GPIB
System Controller
Booster
amp
Pin
Leveled power
Input power (dBm)
Frequency (Hz)
tolerance Target
power
level
DUT’s actual input power (Pin)
DUT’s input power level should be within a specific target range - power leveling.
* Coupler to detect output
power of a booster amp
85
VNA Function Power leveling
VNA Function - Receiver leveling
• Adjusts the source power level using its receiver measurements.
• Replaces existing test systems for power leveling with reducing test complexity.
SA DUT SG
Power
Sensor
Coupler
e.g. GPIB
System Controller
Leveling with rack & stack system VNA’s receiver leveling
Receiver leveling offers fast and accurate leveling
to compensate a booster amp’s drift with a simple
connection.
Booster
amp Pin DUT
V
Booster
amp
Coupler
ATT
(Optional)
Pin
86
High-power Measurements Power leveling
Leveled Input power (Pin)
DUT’s Pin is accurately adjusted (i.e. within +-0.1 dBm) at
target power level of +43 dBm by using the VNA’s receiver
leveling.
Pin (dBm)
0.1 dBm/div
Receiver leveling ON
Receiver leveling OFF
Note: frequency sweep is performed to monitor Pin over frequency.
R1
DUT Booster amp
Coupler
ATT (Optional)
Pin
+43 dBm
Configuration of Power leveling
87
Fixture Simulator
• Fixture Simulator
– Balanced measurements (Mixed-mode S-parameters)
– (De-)Embedding / port matching
– Setup wizard of fixture simulator
– Port matching utility program
Fixture Simulator
DUT
Measured S-
parameters
Port
Extension
Network De-
embedding
Port reference
Z conversion Port Matching
Unbalanced-
Balanced
Conversion
Differential
Port Z
conversion
Differential
Matching
circuit
Embedding
Single-ended S-parameter
Balanced (Mixed-mode) S-parameter
Single-ended Balanced
Zd
Zc
Data Process
Actual
Calibration Plane
Built-in Balanced Measurement
SAW Filters (Bal-Bal) Baluns
Differential Amplifiers Cable
SAW Filters (Unbal-Bal)
Balanced component examples:
44434241
34333231
24232221
14131211
SSSS
SSSS
SSSS
SSSS
22212221
12111211
22212221
12111211
CCCCCDCD
CCCCCDCD
DCDCDDDD
DCDCDDDD
SSSS
SSSS
SSSS
SSSS
DUT
V1 V2
Vdiff
Vcomm
=
2
1*
,
,
V
V
DC
BA
Vcomm
Vdiff
Measure
Single-ended S-parameters
Simulate Hybrid Balun
to extract differential and common
Obtain
Mixed-mode S-parameters
(Balanced and Common-mode
S-parameters)
Mixed-mode S-parameters
Examples of Mixed-mode S-Parameters
Sdd21
Scc21
Mixed-mode S21 for Bal-Bal
Scd21
Sdc21
Sdc11
Sds21
Scs21
Mixed-mode S21 for Single to Bal
Sss11 Ssd12
Sds21 Sdd22
Scs21
Ssc12
Scd22
Sdc22
Scc22
Sdd11 Mixed-mode S11
Balanced SAW filter measurement example
Embedding
50 50 R+jX R+jX
DUT DUT
Complex Port Z Conversion
Embedding/De-embedding and Port Z Conversion
Measure Simulate
DUT
Measured
S-parameter
Embedded Response
Additional
Network
Additional
Network DUT
De-embedded
Response
Measured
S-parameter
Undesired
Network
Undesired
Network
De-embedding
Embedding / De-embedding
Port 1
Port 2
Port 3
Port 4
Port 1
Port 2
Port 3
Port 4
(De-)Embedding of 2-port circuits
(De-)Embedding of 4-port circuits
DUT
DUT
De-embedding
•Accurate characterization of the DUT is achieved by de-embedding S-
parameter (*.s2p) of a fixture.
Calibrated
system(cal
plane at cable
end)
DUT
Connector
RF Cable
DUT
Calibration
Plane
S11
S12
S21
S22
Fixture
Create an S2p file
and de-embed
Embedding Virtual Networks
• Mathematically embed matching circuits on any ports as required.
• Predefined matching topologies or user defined S-parameters networks can
be embedded.
L1
L2
C1
C1
Zd
Zc
Zi
Bal
SAW
Filter
Virtual matching circuits
Balanced SAW Filter Measurement Example
Single-ended (unbalanced)
9x9 S-parameters, S11 to S33
Balanced S-parameters
(both differential and common modes)
Sss11 Ssd12
Sds21 Sdd22
Scs21
Ssc12
Scd22
Sdc22
Scc22
Agilent Restricted
Measurement Specifications
Connections
• Single-ended : Port 1
• Balanced : Port 2
• Balanced : Port 3
Setup
1. Preset : OK
2. Center : 942.5MHz
3. Span : 200MHz
4. Display : Number of Traces: 9
Allocate Traces: |1|2|3|
|4|5|6|
|7|8|9|
5. Select parameter & format as shown on next page
6. Adjust Scale
Band Pass Filter(Single-ended)
F0 : 947.5MHz
50 ohm 50 ohm
PORT 1 PORT 2
Band Pass Filter(Balanced)
F0 : 942.5MHz
50 ohm
200 ohm
PORT 1
PORT 2
PORT 3
Duplexer F0(Tx) : 1880MHz
F0(Rx) : 1960MHz
50 ohm 50 ohm
50 ohm
PORT 1
PORT 2
PORT 3
R
x
T
x
ANT
s1 Handset Component Demo Kit
E5079A
L2
C1
C1
Zd
Zc
Measure Single-ended S-parameters
Measurement parameters
S11 S12 S13
S21 S22 S23
S31 S32 S33
Zi
Measured
S-parameter
Bal
SAW
Filter
Perform Full 3-port Calibration
Measured
S-parameter
(w/Full-3 Cal)
L2
C1
C1
Zd
Zc
Zi
Bal
SAW
Filter
Measured
S-parameter
(w/Full-3 Cal)
Apply Port Extension
Electrical length
Port 1 : 180ps Port 2 : 280ps Port 3 : 280ps
L2
C1
C1
Zd
Zc
Zi
Bal
SAW
Filter
Apply port
extension
Convert to Mixed-mode S-parameters
Measurement Parameters
Sss11 Ssd12 Ssc12
Sds21 Sdd22 Sdc22
Scs21 Scd22 Scc22
Convert to mixed-mode
S-parameter
L2
C1
C1
Zd
Zc
Zi
Bal
SAW
Filter
Measured
S-parameter
(w/Full-3 Cal)
Apply port
extension
Convert to mixed-
mode S-parameter
Convert port
characteristic
impedance*
Modify Port Characteristic Impedance
Port characteristic impedance
Port 1 : 50 ohms
Port 2 : 100 ohms
Port 3 : 100 ohms
* Differential & common impedance are
automatically calculated from defined
single-ended impedance.
L2
C1
C1
Zd
Zc
Zi
Bal
SAW
Filter
Measured
S-parameter
(w/Full-3 Cal)
Apply port
extension
Apply Port Matching
Matching specifications
Port 1 : none
Port 2 : Shunt L = 28nH
Port 3 : Shunt L = 28nH
Convert to mixed-
mode S-parameter
Convert port
characteristic
impedance*
Apply matching
circuit
L2
C1
C1
Zd
Zc
Zi
Bal
SAW
Filter
Measured
S-parameter
(w/Full-3 Cal)
Apply port
extension
Save “State & Cal”
Agilent Restricted
Measurement Specifications
Band Pass Filter(Single-
ended) F0 : 947.5MHz
50 ohm 50
ohm
PORT 1 PORT 2
Band Pass Filter(Balanced)
F0 : 942.5MHz
50 ohm
200 ohm
PORT 1
PORT 2
PORT 3
Duplexer F0(Tx) :
1880MHz
F0(Rx) :
1960MHz 50 ohm 50 ohm
50 ohm
PORT 1
PORT 2
PORT 3
R
x
T
x
ANT
s1 Handset Component Demo Kit E5079A
Electrical length
Port 1 : 180ps
Port 2 : 280ps
Port 3 : 280ps
Port characteristic impedance
Port 1 : 50 ohms
Port 2 : 100 ohms
Port 3 : 100 ohms
Matching specifications
Port 1 : none
Port 2 : Shunt L = 28nH
Port 3 : Shunt L = 28nH
Setup
1. Preset : OK
2. Center : 942.5MHz
3. Span : 200MHz
Setup Wizard of Fixture Simulator Fast and easy measurements with setup wizard
Available at Agilent website at http://www.agilent.com/find/enavba
Agenda
• What measurements do we make?
• Network analyzer hardware
• Error models and calibration
• Applications
• Automation RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED
(A)
TRANSMITTED
(B) INCIDENT (R)
SIGNAL SEPARATION
SOURCE
Incident
Reflected
Transmitted
DUT
SHORT
OPEN
LOAD
Agilent IO Libraries Suite 16 provides
one tool for fast start-up
Suite 16
• Identify and set up LAN,
USB, GPIB, and converter
interfaces
• Identify and communicate
with instruments
• Change addresses and set
interface aliases
• Works with NI-488 software
and NI VISA I/O library
System set-up in
< 15 minutes
Page 109
LAN eXtension for Instrumentation
IP Address
Manufacturer
Model #
Serial #
Firmware rev.
IP Address
Domain name
etc.
Ability to
change the
IP address
LXI devices serve a web page
Page 114
LXI Possibilities
Expert
Troubleshooting
Parallel
operations
Reduce
programming
Long
distance
operations
Internal
network
Timestamp
all data
Higher
throughput
Asset
Management
Flexible
triggering
Smart instruments
No trigger
wires
Eliminate
latency
Software Integration
Agilent ADS
1/26/2011 Page 115
Agilent SystemVue
VEE Pro
Integrated
VBA Programming
Quick Demo Guide
ENA Series Network Analyzer - VBA Programming (UserMenu)
1. Connect DUT to ENA
2. Launch VBA editor, and code VBA program
a. Press [Macro setup] hard key then press VBA Editor soft key
VBA editor
b. Create module and code procedure
Click Insert in the menu bar then click Module
Code as shown below in Module1
c. Save VBA program and exit VBA editor
Click icon of the VBA editor. The Save As dialog box
appears. Specify the file name and location and click Save.
Click icon of the VBA editor.
Procedure overview
1. Connect DUT to ENA
2. Launch VBA editor, and code VBA program
3. Run VBA Macro
4. Add bandwidth search module
5. Apply VBA macro to UserMenu buttons
Required Instrument and fixture
ENA series network analyzer (E5071C or E5061B)
In this demo…
• Code simple VBA macro for bandpass filter measurement
• Apply VBA macro to UserMenu buttons
N-Type Cable
In this demo, we will use BPF (Center frequency =
1.09 GHz) but you can use another filter. Prepare
appropriate cable and adapter to connect between
ENA and DUT.
Figure1. DUT connection DUT
Sub main()
Call Setup
End Sub
Sub Setup()
SCPI.SYSTem.PRESet
SCPI.SENSe.FREQuency.CENTer = “1.09E9”
SCPI.SENSe.FREQuency.SPAN = “200E6”
SCPI.CALCulate.PARameter.Count = 2
SCPI.DISPlay.WINDow.Split = "D12"
SCPI.CALCulate.PARameter(2).DEFine = "S21"
SCPI.SENSe.BANDwidth.RESolution = 1000
MsgBox "Setup done"
SCPI.DISPlay.WINDow.TRACe(1).Y.SCALe.AUTO
SCPI.DISPlay.WINDow.TRACe(2).Y.SCALe.AUTO
End Sub
3. Run VBA macro
Press [Macro Run] Hard key.
The ENA calles main() procedure, and this VBA program will set
up the measurement parameters as shown below. Band pass filter (BPF)
Quick Demo Guide
www.agilent.com/find/ena_vba
4. Add Bandwidth Search Module
a. Open VBA Editor
b. Modify Sub() procedure of Module1 as below code
c. Add below procedure on Module1
d. Save VBA program and run
Click icon, then icon of the VBA editor
Press [Macro Run] hard key.
This code sets the measurement parameter, then make
bandwidth search function as below.
Sub Bandwidth()
SCPI.CALCulate.PARameter(2).SELect
With SCPI.CALCulate.SELected.MARKer
.State = True
.FUNCtion.TYPE = "MAX"
.FUNCtion.EXECute
.BWIDth.State = True
End With
End Sub
Sub Main()
Call Setup
Call Bandwidth
End Sub
5. Apply VBA procedure to UserMenu buttons
a. Open VBA Editor
b. Modify Sub() procedure of Module1 as below code
c. Create UserMenu module
Click E5061B_Objects then Double-Click UserMenu
In the object box in the code window, select UserMenu as
shown below.
d. Code below procedure on UserMenu module
e. Save program and run
Click icon, then icon of the VBA Editor
press [Macro Run] hard key.
Sub Main()
UserMenu.Item(1).enabled = True
UserMenu.Item(2).enabled = True
UserMenu.Item(1).Caption = "Setup"
UserMenu.Item(2).Caption = "Bandwidth"
UserMenu.Show
End Sub
Private Sub UserMenu_OnPress(ByVal ID As
Long)
If ID = 1 Then Module1.Setup
If ID = 2 Then Module1.Bandwidth
UserMenu.Show
End Sub
6. Use UserMenu Buttons
a. Press “Setup” button to run Setup procedure
b. Press “Bandwidth” button to run Bandwidth_Search
procedure
Tips: Command finder Using command finder chapter of the help file, you can easily
find appropriate command for each button. To open help,
press [Help] hard key, then click Programing > Command
Reference > Command Finder.
Sample VBA(s) for the ENA
Page 119 Last update:
Nov 2010
PNA-L World’s most capable value VNA
300 kHz to 6, 13.5, 20 GHz
10 MHz to 40, 50 GHz
ENA-L Low cost VNA
300 kHz to 1.5/3.0 GHz
Agilent VNA Solutions
ENA World’s most popular
economy VNA
9 kHz to 4.5, 8.5 GHz
300 kHz to 20.0 GHz
FieldFox RF Analyzer
5 Hz to 4/6 GHz
PNA-X, NVNA Industry-leading performance
10 MHz to 13.5/26.5/43.5/50/67 GHz
Banded mm-wave to 2 THz
PNA-X
receiver 8530A replacement
Mm-wave
solutions Up to 2 THz
PNA Performance VNA
10 MHz to 20, 40, 50, 67, 110 GHz
Banded mm-wave to 2 THz
Test Accessories
PNA-X Customer Presentation
ENA Series Network Analyzers
9 / 100 kHz to 4.5 / 6.5 / 8.5 GHz
300 kHz to 14 / 20 GHz
5 Hz to 3 GHz
100 kHz to 1.5 / 3 GHz E5061B
E5071C
30 kHz to 4.5 / 8.5 GHz
E5072A
New!
• 2-port
• Wide output power range
• Configurable test set
• 150 dB dynamic range
• Low-freq coverage
• Z-analysis function
• 2-port & 4-port
• Balanced meas.
• Up to 20 GHz
• Option TDR
• Low-cost simple RF NA
• 50 Ω & 75 Ω
E5061B-3L5, LF-RF option
E5061B-115 to 237, RF options
Page 121
Group/Presentation Title
Agilent Restricted
17 December 2012
Accurate Handheld VNA N9923A (4/6 GHz)
◄ Full 2 port vector network Analyzer
◄ CalReady at each test port
◄ Full 2 port QuickCal
◄ O.01 dB/deg C Stability Spec
◄ 100 dB dynamic range
◄ Power meter
◄ Vector Voltmeter (1 – and 2-channel)
◄ Distance to Fault
◄ LAN, USB, mini SD
Quad display CAT Vector volt Meter Power Meter
APPENDIX
122
VNA application examples
– RF amplifier test
– High-power measurement
– Swept IMD measurement
– High-gain amp measurement
12
3
What is intermodulation distortion (IMD)?
• A measure of nonlinearity of amplifiers.
• Two or more tones applied to an amplifier and produce additional intermodulation products.
• The DUT’s output will contain signals at the frequencies: n*F1 +m *F2.
F1 F2 2*F1-F2 2*F2-F1
DeltaF
IM3 relative to
carrier (dBc)
P(F1) P(F2)
P(2*F1-F2)
Frequency
F_IMD = n * F1 + m * F2
ex.)
•Lo F_IM3 = 2 * F1 - F2
•Hi F_IM3 = 2 * F2 - F1
•Lo F_IM5 = 3 * F1 - 2 * F2
•Hi F_IM5 = 3 * F2 - 2 * F1
•Lo F_IM7 = 4 * F1 - 3 * F2
•Hi F_IM7 = 4 * F2 - 3 * F1
12
4
Third-order Intercept Point (IP3)
• The third-order intercept point (IP3) or the third-order intercept (TOI) are often used as figures
of merit for IMD.
F1 F2 2*F1-F2 2*F2-F1
DeltaF
IM3 relative to
carrier (dBc)
P(F1) P(F2)
P(2*F1-F2)
Frequency IP3 can be calculated by the equation using
low-side IM3:
IP3 (dBm) = P(F1) + (P(F2) - P(2*F1-F2)) / 2
When high-side IM3 is used, the equation is:
IP3 (dBm) = P(F2) + (P(F1) - P(2*F2-F1)) / 2
Input power
(dBm)
Output power (dBm)
IIP3
OIP3
Fundamental
(Slope 1:1)
Third-order product
(Slope 1:3)
12
5
P(F1): Power level of low tone
P(F2): Power level of high tone
P(2*F1-F2): Power level of low-side IM3 signal
P(2*F2-F1): Power level of high-side IM3 signal
• ENA with frequency-offset mode (FOM) option
can set different frequencies at the source and
receiver.
• Real-time swept frequency IMD measurements
can be performed.
• Source power calibration and receiver calibration
is available with VNA for accurate absolute power
measurements.
• Using two SGs and a SA with CW signals.
• It requires a controller to synchronize
instruments.
• If many frequencies must be tested, test time
is increased dramatically.
2x SG + SA
Intermodulation Distortion
SG + VNA
12
6
VNA functions
Frequency Offset Mode
• Sets different frequency range for the source and receivers.
• Can be used for harmonics or intermodulation distortion (IMD) measurements with the VNA.
Source and receiver are tuned at the different
frequency range (for harmonics, IMD test etc.)
Source and receiver are tuned at the same
frequency range. (i.e. S-parameter).
Normal Sweep Frequency-offset Sweep
f1
Source
(Port 1) f1
Receiver
(Port 2) f1
Source
(Port 1) f2
Receiver
(Port 2)
12
7
DUT DUT
IMD Measurement
Measurement example (sweep delta)
Power levels of main tones and IM products in
swept frequencies can be monitored with the
VNA’s absolute measurements.
Configuration of IMD measurement with VNA
DUT Combiner
Attenuator
(Optional)
USB/GPIB
Interface 10 MHz REF
SG
VNA
f1
f1 (SG)
f2
f2 (ENA)
f_IM
f_IM
(ENA)
f1 (SG) f2 (ENA)
Lo IM3
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8
IMD Measurement Wizard for the E5072A
Key Features:
• Measurement macro running on the E5072A with intuitive GUI
• Quick setup of two-tone IMD measurements
• Control all necessary equipments from E5072A
– MXG (connected via GPIB/USB interface)
– Power meter & sensor (connected via GPIB/USB interface)
– USB power sensor (connected directly to the ENA’s USB port)
• Guided calibration wizard
• Various measurement sweep types
– Fixed F1 and Swept F2
– Sweep Fc
– Sweep DeltaF
• Various IMD measurement parameters
– Absolute power of fundamental tones (in dBm)
– Power levels of IMD products (absolute in dBm), Low or High-side IM (3rd, 5th, 7th)
– Calculated third-order intercept point (IP3)
Available at: www.agilent.com/find/enavba
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9
VNA application examples
– RF amplifier test
– High-power measurement
– Swept IMD measurement
– High-gain amp measurement
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0
VNA Functions Uncoupled Power
Independent built-in source attenuators to uncouple power level
• Different output power level can be set for port 1 & 2 with independent source attenuators.
• Easy characterization of high-gain power amp without external attenuators on output port.
• More accurate reverse measurement (i.e. S12, S22) with wider dynamic range.
R1
A
R2
B
High-gain amp -85 dBm 0 dBm
ATT = 40 dB
(Port 1) ATT = 0 dB
(Port 2)
Example DUTs:
BTS repeaters, LNA, receivers.
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1
Coupled power (Port 1 = Port 2 = -40 dBm)
Uncoupled power (Port 1 = -40 dBm, Port 2 = 0 dBm)
High-gain amp measurement
S12
S22
S11
S21
DUT: High-gain (30 dB) RF Power amp
K-factor
S12
S22
S11
S21
K-factor
More accurate S12 measurement with uncoupled
power results in better trace of calculated K-factor.
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2
Resources
• Configuration Guide (5990-8001EN)
• Data Sheet (5990-8002EN)
• Quick Fact Sheet (5990-8003EN)
• Technical Overview (5990-8004EN)
• Application Note
– High-power measurement using the E5072A (5990-8005EN)
• ENA Series: www.agilent.com/find/ena
• E5072A Product page: www.agilent.com/find/e5072a
• Campaign page: www.agilent.com/find/e5072a_PR
• E5072A on YouTube: www.youtube.com/user/AgilentVNA#p/u/5/cA83A4qFEZU
Campaign page YouTube page
THANK YOU!
Back to Basics Seminar 134
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