Establishing Traceability for Quantities Derived from Multiple Traceable Quantities

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Establishing Traceability for Quantities Derived
from Multiple Traceable Quantities

• Alberto Campillo, Jian Liu
• Agilent Technologies
• alberto_campillo_at_agilent.com
• jian_liu_at_agilent.com

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Sharing of learning experience

• 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.

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Agenda

• Derived quantity and traceability concept
• Establishing traceability general approach
• Phase noise example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary

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Agenda

• Derived quantity and traceability concept
• Establishing traceability general approach
• Phase noise example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary

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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,)

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Derived quantity concept

• International System of Units (SI)

Base quantity     Base unit  
Name Symbol   Name Symbol
length l, x, r   meter m
mass m   kilogram kg
time, duration t   second s
electric current I, i   ampere A
thermodynamic temperature T   kelvin K
amount of substance n   mole mol
luminous intensity Iv   candela cd
Derived quantity     Derived unit  
Name Symbol   Name Symbol
speed v meter per second m/s
voltage U Volt V (m2 kg s-3 A-1)
phase noise decibel relative to carrier per Hertz dBc/Hz (s)
 
http//www.bipm.org/en/si/si_brochure/
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Derived quantity concept
/

• SI base quantities

top of traceability chain
voltage (Josephson)
resistance (Quantum Hall)
traceable voltage
traceable resistance
NOT EXACTLY SO!
speed
voltage
current
phase noise
Any quantities can be derived
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Derived quantity concept

• International Vocabulary of Metrology (VIM)

JCGM 2002008, International vocabulary of
metrology - Basic and general concepts and
associated terms (VIM)
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Traceability concept

• International Vocabulary of Metrology (VIM)

JCGM 2002008, International vocabulary of
metrology - Basic and general concepts and
associated terms (VIM)
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Agenda

• Derived quantity and traceability concept
• Establishing traceability general approach
• Phase noise example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary

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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!

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Agenda

• Derived quantity and traceability concept
• Establishing traceability general approach
• Phase noise example
• Definition and expressions
• Direct spectrum method
• Phase detector method
• Summary

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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.

f
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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)

When total phase fluctuation in the modulation
sideband ltlt 1 radian (small angle criterion)
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Direct spectrum method
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Direct spectrum method

• Major MU contributors
• Bandwidth normalization (shape of IF filter
  amplifier)
• Amplitude accuracy
• High offset frequency Mismatch

• Phase noise traced to
• Frequency
• RF power
• Attenuation
• Reflection coefficient

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Phase detector method
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Phase detector method

• Major MU contributors
• Phase detector K factor
• Baseband analyzer accuracy
• Test set frequency response
• PLL suppression correction
• High offset frequency mismatch

• Phase noise traced to
• Frequency
• RF power
• AC Voltage
• Attenuation
• Reflection coefficient
• Noise

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Summary

• 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.

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THANK YOU!Questions comments?
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Backup slides
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Phase Noise Overview
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Direct Spectrum Method

• Overall sensitivity limited by SA internal LO

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Phase Detector Method

• 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

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Phase Noise traced to Noise Figure 1

• http//www.hparchive.com/seminar_notes/HP_PN_semin
  ar.pdf

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Phase Noise traced to Noise Figure 2

• http//www.hparchive.com/seminar_notes/HP_PN_semin
  ar.pdf