Download Small Signal to Large Signal

Network Analyzers
From Small Signal
To Large Signal Measurements
Doug Rytting
Slide 1
Agenda
Small Signal Measurements & Error Correction
Compression and AM to PM
Hot S22 Measurements
Load Pull Measurements
Pulse Measurements
Large Signal Network Analyzer Measurements
Slide 2
Network Analyzer Block Diagram
RF
Source
a0
IF
IF
a3
LO
Source
IF
IF
b0
b3
Port - 1
Cable
a1
b2
DUT
b1
Port - 2
Cable
a2
Slide 3
Improvements with Correction
ERRORS REMOVED
ERRORS REMAINING
Port Match
Noise and Residuals
Directivity
Receiver Linearity
Tracking
Drift after Error-Correction
Main Leakage Paths
Stability after Error-Correction
Repeatability of Connectors, etc
Lower Lever Leakage Paths
Errors of Calibration Standards
Slide 4
Improvements with Correction
Slide 5
Calibration Examples – 8 Term Model
Seven or more independent known conditions must be measured
A known impedance (Z 0) and a port-1 to port-2 connection are required
TRL & LRL
Thru (T) or Line (L) with
known S-parameters
[4 conditions]
Unknown equal Reflect (R)
on port-1 and port-2
[1 condition]
Line (L) with known
S11 and S 22
[2 conditions]
TRM & LRM
Thru (T) or Line (L) with
known S-parameters
[4 conditions]
Unknown equal Reflect (R)
on port-1 and port-2
[1 condition]
Known Match (M)
on port-1 and port-2
[2 conditions]
TXYZ & LXYZ
Thru (T) or Line (L) with
known S-parameters
[4 conditions]
3 known Reflects (XYZ)
on port-1 or port-2
[3 conditions]
Traditional
TOSL
(Overdetermined)
Thru (T) with
known S-parameters
[4 conditions]
3 known Reflects (OSL)
on port-1
[3 conditions]
LRRM
Line (L) with known
S-parameters
[4 conditions]
2 unknown equal Reflects
(RR) on port-1 and port-2
[2 conditions]
3 known Reflect (OSL)
on port-2
[3 condition]
Known match (M)
on port-1
[1 condition]
UXYZ
Unknown Thru
Unknown Line (U) with
S12 = S 21
[1 condition]
3 known Reflects (XYZ)
on port-1
[3 conditions]
3 known Reflects (XYZ)
on port-2
[3 conditions]
Slide 6
Agenda
Small Signal Measurements & Error Correction
Compression and AM to PM
Hot S22 Measurements
Load Pull Measurements
Pulse Measurements
Large Signal Network Analyzer Measurements
Slide 7
Output Power (dBm)
Power Sweep - Compression
Saturated
output power
Compression
region
Linear region (slope = small-signal
gain)
Input Power (dBm)
Slide 8
Power Sweep -Gain Compression
CH1 S21
1og MAG
1 dB/ REF 32 dB
30.991 dB
12.3 dBm
C2
0
0
IF BW 3 kHz
START -10 dBm
CW 902.7 MHz
 1 dB compression: input power
resulting in 1 dB drop in
gain
 Ratioed measurement
 Output power available (nonratioed measurement)
SWP 420 msec
STOP 15 dBm
Slide 9
Power Sweep - AM to PM Conversion
1:Transmission
2:Transmission
/M
Log Mag
Phase
1.0 dB/
5.0 deg/
Ref 21.50 dB
Ref -115.7 deg
Ch1:Mkr1
-4.50 dBm 20.48 dB
Ch2:Mkr2
1.00 dB
0.86 deg
2
1
 Use transmission setup
with a power sweep
 Display phase of S21
 AM - PM = 0.86 deg/dB
2
1
1
Start -10.00 dBm
Start -10.00 dBm
CW 900.000 MHz
CW 900.000 MHz
Stop 0.00 dBm
Stop 0.00 dBm
Slide 10
Agenda
Small Signal Measurements & Error Correction
Compression and AM to PM
Hot S22 Measurements
Load Pull Measurements
Pulse Measurements
Large Signal Network Analyzer Measurements
Slide 11
Hot S22 Measurement System
Small signal S-parameters of a nonlinear device in the presence of
a high power drive signal Df away from test frequency.
Osc
a
High
Power
Combine
0
b
b
0
a
1
b
1
DUT
[A]
b
2
a
2
3
a
3
High
Power
Load
High
Power
Osc
Slide 12
Hot S22 Measurement System
S-parameters of a nonlinear device at a defined input or
output power.
a
0
b
b
0
a
1
OSC
b
1
DUT
[A]
b
3
a
3
GA
2
a
2
GB
Slide 13
Agenda
Small Signal Measurements & Error Correction
Compression and AM to PM
Hot S22 Measurements
Load Pull Measurements
Pulse Measurements
Large Signal Network Analyzer Measurements
Slide 14
Load Pull Measurement
Need to measure nonlinear device behavior
under actual operating conditions
Pmax
-1 dB
-2 dB
S22
-3 dB
Low power
High power
Parameter changes vesus
output power level
Constant output power contours versus
output load impedance
Slide 15
Load Pull System
INPUT
IMPEDANCE
AND
POWER
MEASUREMENT
SYSTEM
X
INPUT
TUNER
X
OUTPUT
IMPEDANCE
AND
POWER
MEASUREMENT
SYSTEM
DUT
X
X
OUTPUT
TUNER
Slide 16
Types of Output Tuners
Passive load-pull
Active load-pull
Harmonic load-pull
Simultaneous Drive
OSC
DUT
Slide 17
Harmonic Load Pull System
LO Synthesizer
HP 8360
1 - 50 GHz
Four Channel Frequency Converter
HP 8510C/85110A
b2 a2
a1 b1
LO Synthesizer
Can be Tuned
to Harmonics
T
T
fo
Source Synthesizer
HP 8360
1 - 50 GHz
DUT
Input Amplifier
1 - 50 GHz TWA
Port Drive
PIN Switch
Port 1
Input
Probe
Port 2
Output
Probe
Reflectometer
Mounted on
Prober
2fo
3fo
T
Port 3
Coaxial and
power cals.
T
Slide 18
Agenda
Small Signal Measurements & Error Correction
Compression and AM to PM
Hot S22 Measurements
Load Pull Measurements
Pulse Measurements
Large Signal Network Analyzer Measurements
Slide 19
High Power Device Pulse
Measurements
Control DUT Temperature
Eliminate temperature as a variable
Test high power devices on-wafer at full power
Measure devices in "unsafe" DC operating area
Test "pulsed" devices in a pulsed environment
Test environment = final application (GSM)
Pulsed radars/phased array antennas/high power MMIC's
Improve device characterization data
Model power FET's at full power level
Measure IV curves without temperature effects
Investigate trapping effects in GaAs
Slide 20
Pulse System Capabilities
Gate/Bas
e
T
1
Synchronization of pulses
Drain/Collecto
r
T
2
RF
RF
PW
DC Safe Operating Limit
IV plane characterization
ID
Q2
Q1
Point in pulse vs Frequency
or Pulse profile vs Time
VD
Slide 21
Pulsed Bias/RF Meas System
T
RF Synthesizer
Pulsed-RF
Test Set
LO Synthesizer
T
T
Network Analyzer
Bias Network
Gate / Base
Bias Pulser
Measurement
Controller
T
Drain / Collector
Bias Pulser
T
DC Power Supply
Digital Multimeter
T
Trigger
Pulse Generator
Slide 22
Agenda
Small Signal Measurements & Error Correction
Compression and AM to PM
Hot S22 Measurements
Load Pull Measurements
Pulse Measurements
Large Signal Network Analyzer Measurements
Slide 23
Large Signal Network Analyzer
Response
Acquisition (LSNA)
Stimulus
50 Ohm
or
Tuner
ESG
Complete Spectrum
Waveforms
Harmonics and Modulation
Slide 24
Large Signal Network Analyzer
Measures magnitude and phase of incident and reflected
waves at fundamental, harmonic, and modulation
frequencies.
Calibrated for relative and absolute measurements for
both linear and nonlinear components at the device under
test.
Calculate calibrated voltage and current in both the time
and frequency domains.
Combination of a vector network analyzer, sampling
scope, spectrum analyzer and power meter.
Slide 25
LSNA System Block Diagram
Sampler Front End
Requires high BW IF
Requires Harmonic LO
Slide 26
Sampling Converter Fundamentals
LP
fLO=19.98 MHz = (1GHz-1MHz)/50
RF
50 fLO
100 fLO
1
150 fLO
2
3
IF
Freq. (GHz)
IF Bandwidth: 4 MHz
1
2
3
Freq. (MHz)
Slide 27
LSNA System Block Diagram
Mixer Front End
Requires harmonic sync
Can use high BW IF for modulation
Or low BW IF if no modulation
Slide 28
Nonlinear Calibration - Model
Response
a 0 b0
a3
b3
Acquisition
Stimulus
Modulation
Source
Actual waves at DUT
a1
a2
b1
b2
b2 
 
a2 
b1   K
 
 a1 
Absolute magnitude
and phase error term
0 0 2

 0 0 2
  1 1 0

 1 1 0
2 

2
 
0 
0
b3 
 
a3 
b0 
 
a0 
50 Ohm
or
Tuner
Measured waves
7 relative error terms
same as a VNA
Slide 29
Nonlinear Calibration
Relative calibration at the fundamental and harmonic
frequencies determines the 7 normal error terms.
Power calibration at the fundamental and harmonic
frequencies determines the magnitude of K.
Phase reference generator calibration determines the
phase of K relative to the fundamental frequency.
Reference generator is an impulse that must be accurately
modeled or measured.
Slide 30
Example # 1
Complete device measurement capability using
a Large Signal Network Analyzer (LSNA).
Slide 31
Device Measurement
a1 (t )
a2 (t )
v1 (t )
b1 (t )
b2 (t )
f 0  900MHz
ids
-0.2 V
vg
v2 (t )
-1.2 V
i1 (t )
i2 (t )
vds
Open port
50 Ohm load
Slide 32
Example # 2
Device measurement verification and
measurement-based model improvement.
Slide 33
Model Verification & Improvement
Parameter Boundaries
GaAs pseudomorphic HEMT
gate l=0.2 um w=100 um
MODEL TO BE OPTIMIZED
“Chalmers Model”
generators apply LSNA measured waveforms
“Power swept measurements under mismatched conditions”
Slide 34
Model Verification & Improvement
During OPTIMIZATION
Voltage - Current State Space
voltage
current
gate
drain
Time domain waveforms
gate
drain
Frequency domain
Slide 35
Model Verification & Improvement
After OPTIMIZATION
Voltage - Current State Space
voltage
current
gate
drain
Time domain waveforms
gate
drain
Frequency domain
Slide 36
Vector Network Analyzer
References
Slide 37
Large Signal Network Analyzer References
Slide 38