Precision Power Measurement Solutions from Bird
description
Transcript of Precision Power Measurement Solutions from Bird
Precision Power Measurement Solutions
from Bird
Precision Power Measurement Solutions
from Bird
Agenda• National Standards Traceability- Challenges &
Bird’s Solution• RF Metrology Paths at Bird Electronic Corporation
– High power RF Calorimetry– Low power microwave attenuation– Low power microwave power– MCS (master calibration system)– Test Setups & system considerations
• 4020 Series Power Sensors and the 4421 Power Meter
• Typical Field Power Measurement Systems
National Standards Traceability- Challenges & Bird’s Solution
Generic Traceability Path
National Reference Standard
Measurement Reference Standard
Working Standard
NIST
Bird Metrology
Bird Manufacturing Facility
Power Sensors
Power Measurement Requirements of the Semiconductor Industry
Power
Frequency
Various frequency & power combos
13.56 Mhz
40 kW
Accuracy Capability of the Scientific Community
Power
Frequency
Bird’s performance range& capability
NIST, NPL etc.
Accuracy Capability of the Scientific Community
Power
Frequency
Bird’s performance range& capability
NIST, NPL etc.
Calorimetry Path
Precision Attn & Power Path
Bird’s Multi-Path Solution
Primary Lab
MCS TransferStandard
WorkingStandard
PrimaryStandard
NIST AttenationStandard
NIST FixedAttenuator
Set
WorkingStandard
NISTStandard
Working Standard
Measurement Ref.Standard
Test Setups
NIST AC & DCStandard
4027, 4028 4024, 4025 Model 43
Precision 60 HzPower Analyzer
High PowerCalorimeter
Low Power Precision Attenuator
RF & Microwave Path
Low PowerRF & Microwave Power Path
High PowerRF Calorimetric Path
Couplers + Power Meter
VNA ThermistorMount
ThermistorCN Mount
Micro-Calorimeter
< 10 mw
Coupler VerificationCal FactorVerification
< 10 mw
AC Voltage &Current Stds.
MCS TransferStandard
Test Setups
4027, 4028 4024, 4025 Model 43
Calibration Subtleties of the Bird System
• +/- 1% calibration requirements dictate daily calibration• +/- 3% is calibrated every 6 months• +/- 5% is calibrated annually• Cross correlations are on-going and constant• Multiple paths are used to cross correlate high power &
high frequency standards • It is capital intensive, time consuming, and demands
high skill levels, but worth every effort in order to guarantee the high accuracy demands of the semiconductor industry
RF Metrology Paths at Bird Electronic Corporation
• High power RF Calorimetry
• Low power microwave attenuation
• Low power microwave power
• MCS (master calibration system)
• Test Setups & system considerations
Primary Lab
Working Standard
Measurement Ref.Standard
NIST AC & DCStandard
Precision 60 HzPower Analyzer
High PowerCalorimeter
AC voltage &Current Stds.
High Power RF Calorimetric Path
• Calorimetry is the critical link between high power AC standards & high power RF standards
8860
6091
Power (kW) = .263 x flow rate (GPM) x T (0C)
Calorimetric Power Meters
Bird Metrology
Manufacturing Facility
Calorimeter Block Diagram
Characteristics of Calorimetric Power Meters
• Highly Accurate, Especially When Using 60Hz Substitution Technique
• Measures True Heating Power, Regardless of Harmonic Content or Modulation Characteristics of Signals
• Requires Careful Setup and Maintenance, Due to Coolant Characteristics
• Long Settling Time
Specific Heat of Water
Precision AC Power
Meter RF
Calorimeter
RF
Source
60 HzAC Source
• Measure 60 Hz power into calorimeter w/AC Power meter• Adjust calorimeter display to match AC power meter• Accuracy of AC standard has now been transferred to calorimeter• When RF is supplied to load, read calibrated watts from calorimeter display
AC Substitution Method
AC Substitution Technique
• Use Low Distortion 60Hz Source• Calibrate Calorimeter Using Precision 60Hz Power
Meter (Accuracy = <0.1%)• Apply Unknown RF Source to Calorimeter• Adjust Coolant Flow Rate to Maintain ΔT Across
Load of > 2º C
• Allow 1 hour For Stabilization
Transfer of Accuracy from AC to RF
frequency
VSWR
RFAC (60 Hz)
• Calorimetric load has virtually identical response at both AC & RF
% Error
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Days
Error
Calorimetric Stability
MCS TransferStandard
NIST AttenuationStandard
NIST FixedAttenuator
Set
WorkingStandard
VNA
Coupler verification
< 10 mw
MCS TransferStandard
Low Power Precision AttenuatorRF & Microwave Path
• Provides the important link between low power, high frequency attenuation values & high frequency coupling values
Working Standard
PrecisionCoupler
• Transfers the accuracy of the VNA to the precision coupler when the coupling value is determined
VNA
Attenuation Standards
VNA
Attenuation Kit
• Attenuation kit traceable to NIST
WorkingStandard
PrimaryStandard
NISTStandard
ThermistorMount
ThermistorCN Mount
Micro-Calorimeter
< 10 mw
Cal Factorverification
Low PowerRF & Microwave Power Path
Provides the link between highfrequency low power standards
and high frequency power meters
MCS TransferStandard
MCS TransferStandard
Working Standard
Thermal PowerMeter
CN ThermisterMount
• Cal factor of power meter is verified with reference to Thermister mount
MCS Transfer Standard
MCS TransferStandard
MCS TransferStandard
Provides the combinational accuracyof calibrated high frequency power& coupling standards into a single calibrated device that can be used as a measurement standard in a high frequency, high power test setup
Directional Coupler - Thermal Power Meter MCS Standard
Characteristics of Directional Coupler-Thermal Power Meter Standards
• Wide Dynamic Range• Useful Frequency Range Determined by Directional Coupler• Complicated Error Budget
– Internal Reference Uncertainty– Mismatch Uncertainty– Calibration Factor Uncertainty
• Fundamental Accuracy Limited by Knowledge of Directional Coupler Attenuation, as well as Power Meter Error Sources.
• Mismatch Uncertainty is a Major Contributor to Total Uncertainty
Precision Power Measurement Test Setups
Test Setups
4027, 4028 Model 43
Test Setups
4027, 4028 4024, 4025 Model 43
These two measurements mustagree within +/- .2%
4027A +/-1% Calibration System
Test Results
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
5 10 15 20 25 30 35 40 45 50 55 60
Elapsed Time (minutes)
Dif
fere
nc
e f
rom
Ca
lori
me
ter
(%)
SN 11569
MCS-59 w ith 11569
SN 11596
MCS-59 w ith 11596
SN 11597
MCS-59 w ith 11597
SN 11598
MCS-59 w ith 11598
Test Results 4027A
5 kW RF Generator at 13.56 MHz
Bird 4020AMPower Sensor
Bird 4421 Power Meter
RF Matching Network
Plasma Etching
Chamber
Mismatches are present at each interconnection of system components
Bird Oil load
p1p1
p1
p2
p2 p2
p2
A Typical Field Calibration Setup
p1 p2
p2SS
p1p2Sp2p1p2S
p2 +/- p1p2p2 = p2’
Total reflected signal
Mismatch Uncertainty
p2 +/- p1p2p2 = p2’1 + p2’
1 – p2’
1 + ( p2 +/- p1p2p2 ) 1 - ( p2 +/- p1p2p2 )
VSWR (apparent) = =1 + p2 +/- p1p2p2
1 - p2 -/+ p1p2p2
Recognize that this expression can be approximated as the product of
VSWR (apparent) =
1 + p2
1 – p2
x1 +/- p1p2p2
1 -/+ p1p2p2 =
1 +/- p1p2p2 + p2 +/- p1 p32
1 -/+ p1p2p2 + p2 +/- p1 p32
Then:
VSWR (true) x 1 +/- p1p2p2
1 -/+ p1p2p2
~ VSWR (apparent)
Very small contribution
Mismatch Uncertainty
VSWR (true) x 1 +/- p1p2p2
1 -/+ p1p2p2
~ VSWR (apparent)
• The true VSWR is multiplied by an uncertainty factor which can only be controlledby carefully choosing the reflection coefficients (p1 and p2) at the source and test points
1 - p1p2p2
1 + p1p2p2
1 + p1p2p2
1 - p1p2p2
1 + p2
1 – p2
Lower limit of multiplier factor =
Upper limit of multiplier factor =
Lower uncertainty limit of measured VSWR =
= F-
F-
= F+
1 + p2
1 – p2
Upper uncertainty limit of measured VSWR = F+
Mismatch Uncertainty
Where:
Pg = Reflection Coefficient of Source
Pl = Reflection Coefficient of Load
Pg and Pl are FREQUENCY DEPENDENT QUANTITIES!
Mu (%) = 100 [(1 Pg Pl)2 – 1]±
Mismatch Uncertainty
VSWR Mismatch Uncertainty
-3
-2
-1
0
1
2
3
1 2 3 4 5
Load VSWR
VS
WR
Un
ce
rta
inty
1.1 source VSWR
1.1 source VSWR
1.5 source VSWR
1.5 source VSWR
2.0 Source VSWR
2.0 Source VSWR
2.5 Source VSWR
2.5 Source VSWR
3.0 Source VSWR
3.0 Source VSWR
3.5 Source VSWR
3.5 Source VSWR
p1 p2
p2SS
p1p2Sp2p1p2S
S(1 +/- p1p2)
Total transmitted signal
+/- dB (ripple) = 20 log | 1- p1p2 |
Transmission Uncertainty
• If data is taken at discrete points, then each individualreading carries an uncertainty of +/- x dB
High point
Low point
Ripple averagedout
flatness Measurementuncertainty
Transmission Uncertainty
Transmission Uncertainty
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
1 2 3 4 5
Load VSWR
Un
cert
ain
ty +
/- d
B 1.1 Source VSWR
1.5 Source VSWR
2.0 Source VSWR
2.5 Source VSWR
3.0 Source VSWR
3.5 Source VSWR
3.5 Source VSWR
1.1 Source VSWR
Transmission Uncertainty
0
0.05
0.1
0.15
0.2
0.25
15 20 25 30 35 40
Load Return Loss (dB)
Un
cert
ain
ty +
/- d
B 1.1 Source VSWR
1.15 Source VSWR
1.2 Source VSWR
1.25 Source VSWR
1.3 Source VSWR
1.35 Source VSWR
Prototype RF Delivery System Gain/Mismatch Analysis
No. Device Return Loss Watt Budget
(dB) (dB) (db)Input Output Mag. Ripple Watts In Watts out dbm out stage loss Cumulative loss
1 Generator 25.00 1,700.0 62.30 0.0
2 cable 25.00 30.00 -0.010 0.03 1700.0 1,696.1 62.29 3.9 3.93 Power Sensor 30.00 30.00 -0.025 0.02 1696.1 1,686.4 62.27 9.7 13.64 cable 30.00 30.00 -0.010 0.02 1686.4 1,682.5 62.26 3.9 17.55 Matching Network 30.00 30.00 -0.050 0.02 1682.5 1,663.2 62.21 19.3 36.86 cable 30.00 37.00 -0.010 0.01 1663.2 1,659.4 62.20 3.8 40.67 termination 37.00 8 62.159 62.24
10 Low Uncertainty Hi Uncertainty Delta Watts
Total -0.11 +/- 0.05 1659.4 1,642.1 1,676.8 40.6 34.7
Gain/Loss
PowerSensor
RFGenerator
Cable
Termination
MatchingNetwork
Cable Cable
Example of Typical RF System Error Budget
Prototype RF Delivery System Gain/Mismatch Analysis
No. Device Return Loss Watt Budget
(dB) (dB) (db)Input Output Mag. Ripple Watts In Watts out dbm out stage loss Cumulative loss
1 Generator 25.00 1,700.0 62.30 0.0
2 cable 25.00 26.44 -0.010 0.05 1700.0 1,696.1 62.29 3.9 3.9adapter 26.44 26.44 -0.005 0.04 1696.1 1,694.1 62.29 2.0 5.9adapter 26.44 26.44 -0.005 0.04 1694.1 1,692.2 62.28 1.9 7.8
3 Power Sensor 30.00 30.00 -0.025 0.02 1692.2 1,682.5 62.26 9.7 17.5adapter 26.44 26.44 -0.005 0.04 1682.5 1,680.5 62.25 1.9 19.5adapter 26.44 26.44 -0.005 0.04 1680.5 1,678.6 62.25 1.9 21.4
4 cable 26.44 26.44 -0.010 0.04 1678.6 1,674.7 62.24 3.9 25.3adapter 26.44 26.44 -0.005 0.04 1674.7 1,672.8 62.23 1.9 27.2
5 Matching Network 30.00 30.00 -0.050 0.02 1672.8 1,653.7 62.18 19.1 46.3adapter 26.44 26.44 -0.005 0.04 1653.7 1,651.8 62.18 1.9 48.2adapter 26.44 26.44 -0.005 0.04 1651.8 1,649.9 62.17 1.9 50.1
6 cable 26.44 26.44 -0.010 0.04 1649.9 1,646.1 62.16 3.8 53.9adapter 26.44 26.44 -0.005 0.04 1646.1 1,644.2 62.16 1.9 55.8adapter 26.44 26.44 -0.005 0.04 1644.2 1,642.3 62.15 1.9 57.7
7 termination 37.00 61.90 62.41 Low Uncertainty Hi Uncertainty Delta watts
Total -0.15 +/- 0.26 1646.1 1,547.7 1,742.6 57.7 194.9
Gain/Loss
PowerSensor
RFGenerator
Cable
Termination
MatchingNetwork
Cable Cable
These two measurements mustagree within +/- .2%
4027A +/-1% Calibration System
Effects of Harmonics on Power Measurement
• 4027 Power Sensor Detector Scheme is Very Sensitive to Harmonics in the Signal.
• 4027 is Calibrated with Signals Having Harmonics of Less than –60dBc.
• Signals with Harmonic Content Greater Than –60dBc will Cause Offsets in Power Readings
• Effects of Harmonics are Determined not Only by Diode Response, but Also by Directional Coupler Response Characteristics, as well as Phase Relationships of Harmonic.
Effects of Harmonics on Power Measurement
Worst Case Errors
Harmonic Level
% Error with One Harmonic
% Error with Two
Harmonics
% Error with Three Harmonics
-55 0.36% 0.70% 1.00%-50 0.63% 1.10% 1.80%-45 1.10% 2.10% 2.90%-40 1.90% 3.90% 5.80%
Effects of Modulation on Power Measurement
• Detector Scheme Used in 4027 is Sensitive to Amplitude Modulation of the Signal.
• Magnitude of Change in Power reading is Related to Power Level and Instrument Range.
• Approximate Error:– At 10% of Full Scale: 5% AM Results in 2% Error– At 90% of Full Scale: 5% AM Results in 8% Error
Additional Tips for MakingAccurate Power Measurements
• Know the effects of the mismatches present in the system architecture on the power measurement uncertainty
• Avoid the use of multiple adapters or non-compensated (high VSWR) adapters between cables and components
• Perform a system error budget to quantify the effects of mismatches and component tolerances in the system
• Avoid the use of long interconnecting cables, as the ripple period will be more frequent as the length is increased for a given frequency
• Use coupler based measurement techniques when the load is unstable or poor in performance compared to the system line impedance
• Averaging techniques over wider frequency bands can be effective in minimizing the effect of mismatch uncertainties
4020 Series Power Sensors and the 4421 Power Meter
4421/4020 Series Power Meters
• Highly Accurate, Highly Repeatable Power Meter System
• Long Product History, Introduced in 1988• Has Become the Power Meter of Choice in
Semiconductor Processing Applications• Extremely Wide Dynamic Range
• Designed for Service in Semiconductor Processing Applications
• 1% Accuracy at Calibration Points
• Several Models to Address Specific Semiconductor Power Levels and Frequencies
Model Power Range Frequency VSWR Range Directivity Insertion Loss
4027A12M 300 mW to 1 kW 10-15 MHz 1.0 to 2.0 28 dB <0.05 dB
4027A250K 3 W to 10 kW 250-400 kHz 1.0 to 2.0 28 dB <0.05 dB
4027A400K 3 W to 10 kW 400-550 kHz 1.0 to 2.0 28 dB <0.05 dB
4027A800K 3 W to 10 kW 800-950 kHz 1.0 to 2.0 28 dB <0.05 dB
4027A2M 3 W to 10 kW 1.5-2.5 MHz 1.0 to 2.0 28 dB <0.05 dB
4027A4M 3 W to 10 kW 3-5 MHz 1.0 to 2.0 28 dB <0.05 dB
4027A10M 3 W to 10 kW 10-15 MHz 1.0 to 2.0 28 dB <0.05 dB
4027A25M 3 W to 10 kW 25-30 MHz 1.0 to 2.0 28 dB <0.05 dB
4027A35M 3W to 10 kW 35-45 MHz 1.0 to 2.0 28 dB <0.05 dB
4027A60M 3W to 6kW 45-65 MHz 1.0 to 2.0 28dB <0.05 dB
±
4027A PrecisionPower Sensor
• First generation diode detectors operate over transition region of diode response curve limiting use in modulated communications systems.
• The entire dynamic range of the 4027 series sensor is contained within the square law operating range of the detector
• Sensor will behave similar to a thermal device, responding to the heating power of the signal being measured
=VOUT
VIN
5.77
2
4027 true average responding detector scheme
4027A Power Sensor
LP Filter
LP Filter
4027F Power Sensor
Error Source 4027A Limit R2
1 Calibration Standards Uncertainty ± 0.4% 0.162 Frequency Response Error 0.0% 03 Dynamic Linearity ± 0.5% 0.254 Temperature Effects ± 0.5% 0.255 Noise ± 0.5% 0.25
Worst Case Error ± 1.9%RSS (Probable) Error ± 0.91%
Notes:
Based upon a temperature range of +35 degrees celcius.
Error Budget
4027A Power Sensor
-0.50
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.50 1.00 1.50 2.00 2.50 3.00
S/N#11758
S/N#11759
S/N#11822
S/N#11823
S/N#11817
S/N#11818
S/N#11820
S/N#11821
S/N#11824
S/N#11825
S/N#11826
4027A10M Serial #
Power Levels (kW)
% Error
4027A Typical Linearity, 13.56 MHz
Power Levels in (kW)
11596 11597 11598
.5kw 0.00 0.00 0.601kw 0.00 0.00 0.20
1.5kw 0.00 0.00 0.102.0kw 0.00 0.00 -0.072.5kw 0.00 0.00 -0.503.0kw 0.00 0.00 0.00
4027A10M Serial #
4027A Typical Linearity, 12 MHz
Time (Min) 15 Min Warmup MCS-59 (w)
4027A10M (w) MCS-59 (w)
4027A10M (w) MCS-59 (w)
4027A10M (w)
0 99.8 99.8 1009 1009 3.01 3.015 99.6 99.6 1008 1008 3.01 3.0110 99.5 99.5 1009 1009 3.00 3.0015 99.6 99.6 1010 1010 2.99 2.9920 99.7 99.7 1012 1012 2.98 2.9825 100 100 1013 1013 2.98 2.9830 100 100 1011 1011 2.99 2.9935 100 100 1009 1009 2.99 2.9940 99.6 99.6 1011 1011 2.98 2.9845 99.3 99.3 1013 1013 2.99 2.9950 99.6 99.6 1015 1015 2.99 2.9955 99.4 99.4 1013 1013 2.97 2.9760 99.3 99.3 1009 1009 2.97 2.97
3000w1000w100w
4027A10M S/N#11820
Short Term Drift at Elevated Power Level
4028A 1-5/8” or 3-1/8”
Transmission Line
Higher Power 4028 Capability
• Similar Accuracy To Other 4027 Models
• Uses Larger Transmission Line (1-5/8” or 3-1/8”) Flanged or Unflanged
• Power Measurement Capability Up To 40Kw
Typical Field Power Measurement Systems
SourceAmplifier
DirectionalCoupler High Power
Termination
Forwardwatts
Reversewatts
Wattmeter
p2p1p1p1 p2
p2
A Typical Power Measurement SetupUtilizing a Directional Coupler
Coupler Based MeasurementsAdvantages:• Typically not limited by power- very little power dissipated• Typically have good thru line reflection coefficients• Forward Power readings are basically isolated from load
stability issues• Allows in-line monitoring of signal with actual system load
Disadvantages:• Must know the coupling value very accurately• Directivity limits reflected power reading• Frequency bandwidth limited
Source
Amplifier
Attenuator
Forwardwatts
Wattmeter
• Knowledge of the attenuation factor and stability is crucialto making a precise power measurement
A Typical Power Measurement Setup utilizing an Attenuator and Thermal Power Meter
A Typical Power Measurement Setup utilizing an Attenuator and Thermal Power Meter
ThermalSensor
Forward attenuation +/- attn. Output Low High +/- % fwdPower tolerance power reading reading power change
1000 30 0.01 1 0.998 1.002 0.23
1000 30 0.1 1 0.977 1.023 2.28
1000 30 0.25 1 0.944 1.059 5.59
1000 30 0.5 1 0.891 1.122 10.87
• Assuming nominal attenuation value can lead to significant errors
• Errors can be minimized by calibrating the attenuator at the specificfrequency or band of frequencies
Attenuators and Their EffectOn Accuracy
Attenuators and Their EffectOn Accuracy
Attenuator Based Measurements
Advantages:• Wideband frequency response, DC coupled• Convenient to use, eliminates a termination
Disadvantages:• Limited in power dissipation• Attenuation accuracy is often not precise, not
as stable• Reflection coefficients are generally higher
Attenuator Based Measurements
• Uncertainties Associated With This System– Input Mismatch Uncertainty (Typically Small Due to Low
Input VSWR)– Output Mismatch Uncertainty– Uncertainties Associated With Thermal Power Meter – Attenuation Factor Uncertainty– Stability of Attenuation Factor Over Temperature– Additional Thermal Errors Due To Excessive Load
Temperatures Affecting Thermal Power Sensor
When an attenuator is used, obtain the calibrated attenuation factor from the manufacturer (or make the measurement yourself) for best possible precision measurements.
Summary
• National Standards Traceability- Challenges & Bird’s Solution– Bird’s multi-path solution and test capabilities make it unique
in the industry• RF Metrology Paths at Bird Electronic Corporation
– High accuracy transfer of standards at every step of the way– Know the concepts behind the error sources in a test setup
• 4020 Series Power Sensors and the 4421 Power Meter– +/- 1% power sensor ideal for semiconductor industry
• Typical Field Power Measurement Systems– Know your system and the errors associated with it