Transcript Establishing Traceability for Quantities Derived from

2011 NCSL International
Workshop and Symposium
Establishing Traceability for
Quantities Derived from
Multiple Traceable Quantities
Alberto Campillo, Jian Liu
Agilent Technologies
[email protected]
[email protected]
Sharing of learning experience
2011 NCSL International
Workshop and Symposium
• Target audience:
• Engineers new to metrology and traceability
• Learning objectives:
• Concept of SI, base quantity, derived quantity and traceability.
• General approach of establishing traceability.
• Concept, measurement techniques and traceability of phase noise.
Agenda
• Derived quantity and traceability: concept
• Establishing traceability: general approach
• Phase noise: example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary
2011 NCSL International
Workshop and Symposium
Agenda
• Derived quantity and traceability: concept
• Establishing traceability: general approach
• Phase noise: example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary
2011 NCSL International
Workshop and Symposium
Introduction
• Traced to the same quantity
STD weight: 50 g ± 0.1 g
UUT weight: 50 g ± 1 g
• Derived from several different quantities
• v=d/t
• I=V/R
• phase noise = f(x1,x2,…)
2011 NCSL International
Workshop and Symposium
2011 NCSL International
Workshop and Symposium
Derived quantity concept
International System of Units (SI)*
Base quantity
Name
length
mass
time, duration
electric current
thermodynamic temperature
amount of substance
luminous intensity
Derived quantity
Name
speed
voltage
phase noise
…
* http://www.bipm.org/en/si/si_brochure/
Base unit
Name
meter
kilogram
second
ampere
kelvin
mole
candela
Symbol
l, x, r…
m
t
I, i
T
n
Iv
Symbol
v
U
L(f)
…
Derived unit
Name
meter per second
Volt
decibel relative to carrier per Hertz
…
Symbol
m
kg
s
A
K
mol
cd
Symbol
m/s
V (m2 kg s−3 A−1)
dBc/Hz (s)
…
2011 NCSL International
Workshop and Symposium
Derived quantity concept
SI base quantities =/ top of traceability chain
voltage
(Josephson)
resistance
(Quantum Hall)
traceable
voltage
traceable
resistance
NOT EXACTLY SO!
speed
voltage
phase noise
current
Any quantities
can be derived
Derived quantity concept
2011 NCSL International
Workshop and Symposium
International Vocabulary of Metrology (VIM)*
* JCGM 200:2008, International vocabulary of metrology - Basic and general concepts and associated terms (VIM)
Traceability concept
2011 NCSL International
Workshop and Symposium
International Vocabulary of Metrology (VIM)*
* JCGM 200:2008, International vocabulary of metrology - Basic and general concepts and associated terms (VIM)
Agenda
• Derived quantity and traceability: concept
• Establishing traceability: general approach
• Phase noise: example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary
2011 NCSL International
Workshop and Symposium
Establishing traceability:
general approach
Required content:
• Measurand
• Measurement method
• Measurement equation(s)
• Uncertainty equation(s)
• MU contributors
• Final MU
• Supporting evidences
Physical principle: most essential!
2011 NCSL International
Workshop and Symposium
Agenda
• Derived quantity and traceability: concept
• Establishing traceability: general approach
• Phase noise: example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary
2011 NCSL International
Workshop and Symposium
2011 NCSL International
Workshop and Symposium
Definition and expressions
Phase noise: short-term frequency stability in frequency domain
Expression 1:
• Single sideband power
• 1 Hz bandwidth
• frequency f offset from the
carrier
• referenced to the carrier
frequency power.
 Noise Power in 1 Hz BW 
L ( f )  10log 

Total
Signal
Power


f
L ( f )[dBc/Hz]  Pn [dBm/Hz]  Ps [dBm]
2011 NCSL International
Workshop and Symposium
Definition and expressions
Expression 2:
• Spectral density of phase
fluctuations
• Phase variance per 1 Hz BW
• In dB when referenced to 1
rad/sqrt(Hz)
S ( f ) 
2
rms
f
BW used to measure rms
 rad 2 


 Hz 
When total phase fluctuation in the modulation sideband
<< 1 radian (small angle criterion):
1
L ( f )  S ( f )
2
Direct spectrum method
2011 NCSL International
Workshop and Symposium
Spectrum Analyzer
8563A
SPECTRUM ANALYZER
26.5 GHz
9 kHz -
UUT
L ( f )[dBc/Hz]  Pn [dBm/Hz]  Ps [dBm]
2011 NCSL International
Workshop and Symposium
Direct spectrum method
Major MU contributors:
• Bandwidth normalization
(shape of IF filter & amplifier)
• Amplitude accuracy
• High offset frequency
Mismatch
L ( f )[dBc/Hz]  Pn [dBm/Hz]  Ps [dBm]
Phase noise traced to
• Frequency
• Attenuation
• RF power
• Reflection coefficient
2011 NCSL International
Workshop and Symposium
Phase detector method
S ( f ) 
2
rms
f
BW used to measure rms
2011 NCSL International
Workshop and Symposium
Phase detector method
Major MU contributors:
• Phase detector K factor
• Baseband analyzer accuracy
• Test set frequency response
• PLL suppression correction
• High offset frequency mismatch
S ( f ) 
2
rms
f
BW used to measure rms
Phase noise traced to
• Frequency
• Attenuation
• RF power
• Reflection coefficient
• AC Voltage
• Noise
Summary
2011 NCSL International
Workshop and Symposium
• Derived quantity & traceability: concept
• Derived quantity in SI and on traceability chain are not the same
• Measurement uncertainty determines the validity of traceability
• Establishing traceability: general approach
• Details from measurement method to final MU should be documented.
• Pay special attention to the physical principle.
• Phase noise: example
• Different measurement methods and ranges may give different
traceability.
2011 NCSL International
Workshop and Symposium
THANK YOU!
Questions & comments?
2011 NCSL International
Workshop and Symposium
BACKUP SLIDES
Phase Noise Overview
2011 NCSL International
Workshop and Symposium
2011 NCSL International
Workshop and Symposium
Direct Spectrum Method
Spectrum Analyzer
8563A
UUT
Overall sensitivity limited by SA
internal LO
SPECTRUM ANALYZER
26.5 GHz
9 kHz -
Phase Detector Method
2011 NCSL International
Workshop and Symposium
PROS
• AM noise suppression
• Low overall noise floor
• Wide offset frequency range
• Wide carrier frequency range
CONS
• Requires an extra reference source (and downconverter) with
much lower phase noise (15 dB less than the UUT)
• High drift rate UUT requires high peak-tune-range (PTR)
reference source
• Close-in measurements require additional correction
Phase Noise traced to Noise Figure 1
http://www.hparchive.com/seminar_notes/HP_PN_seminar.pdf
2011 NCSL International
Workshop and Symposium
Phase Noise traced to Noise Figure 2
http://www.hparchive.com/seminar_notes/HP_PN_seminar.pdf
2011 NCSL International
Workshop and Symposium