sergio mariotti [email protected] göteborg, jun 19 th 2006 institute of radioastronomy, -...

Sergio Mariotti [email protected] Göteborg, jun 19th 2006

INSTITUTE OF RADIOASTRONOMY, - ITALYINSTITUTE OF RADIOASTRONOMY, - ITALY UNIVERSITY “TOR VERGATA” - ROMEUNIVERSITY “TOR VERGATA” - ROME

1 INAF – Institute of Radioastronomy- Bologna – Italy2 Elettronica s.p.a. – V. Tiburtina Valeria, Rome – Italy3 University “Tor Vergata” – Electronic Eng. Dept. – Rome - Italy

Reduction of the UncertaintyReduction of the Uncertainty on Noise Figure Measurements on Noise Figure Measurements

A. Cremonini 1, M. De Dominicis 2, S. Mariotti 1 , E. Limiti 3, A.Serino 3

WHYWHY Reduce Uncertainty? Reduce Uncertainty?

Sergio Mariotti Göteborg, jun 19th 2006


Uncertainty should be much lower than the value to be measured

3.5E-02

1E-13

5E-07

5E-03

1.E-14 1.E-12 1.E-10 1.E-08 1.E-06 1.E-04 1.E-02 1.E+00

Time

Voltage

RF Impedance

Noise Figure

Absolute Uncertainty

+/- 3.5 % = +/- 0.15 dB

For a receiver:NF = 0.3 +/-0.15 dBTe = 21 +/- 11 K



• Looking for and Find Sources of Uncertainty (U)

HowHowReduce Uncertainty? Reduce Uncertainty?

• Analyze and propagate uncertainty

• Minimize the sources wherever it is possible

• Since U(ENR) is dominant, let do calibration of NoiseSource with a Secondary Standard (liq. N2)

• Let Practical operations accurate as possible



Involved EnvironmentsInvolved Environments

Room TemperatureRoom Temperature Cryogenic /on DewarCryogenic /on Dewar

- easier- faster- accurate

- less jitter- more realistic- accurate

2 2 2 21 0.11 0.02 0.077 0.098 0.167 cu NF dB



Sources (causes) of Uncertainty:Sources (causes) of Uncertainty:Propagation, Math Formulation Propagation, Math Formulation

212 1

1

1FF F

G

2 2

2 2 212 21 12 2

1 1 1

2 2

2 22 12 21

1 1 1 1 1

1

c

dB dB

F Fu NF u NF u NF

F FG

F F Fu G u ENR

FG F FG

F12

F2 = 10dBF1 = 3 dBG1= 15 dB

•Depend on many causes, even Depend on many causes, even U(ENR)U(ENR)

Depend on Depend on U(ENR)U(ENR)



Causes of Uncertainty:Causes of Uncertainty:Graphical - IntuitiveGraphical - Intuitive

Te Tc Th

Pc

Ph

Te Tc Th

Pc

Ph

Reducing Tc, will reduce U(Te) Te Tc Th

Pc

Ph

Reducing U(Th) and U(Tc) will reduce U(Te)

Increasing Th don’t reduce U(Te) , because U(Th)/Th is a constant

Instead increase Th may generate non-linearity . Yopt 2…5



Causes of Uncertainty:Causes of Uncertainty:Practical, Tips&TricksPractical, Tips&Tricks

|S11 ON| , |S11 OFF| < - 33 dBSelected AttenuatorPT 100 A

Cascade Ferrite Isolators

Environment: Thermostatic room,

NO cables movement

Precision Connectors / Connector Care

Type A Uncert. << Type B Uncert.

10 dB6 dB



Other causes of Uncertainty:Other causes of Uncertainty:

Approximate Expression T e

1

1 NS DUT 2

1 290 T e

0.1

1.0

10.0

100.0

0 10 20 30 40 50 60 70 R.L. NoiseSource + R.L. DUT [dB ]

+/-

T

e [

oK

]

NS DUT

Mismatch: A closed form expression doesn’t exist

Liq. N2

77 K POWER METER

800 W Liq. N2

77 K POWER METER

3200 W Liq. N2

77 K POWER METER

9400 W Liq. N2

77 K POWER METER

800 W Liq. N2

77 K POWER METER

3200 W Liq. N2

77 K POWER METER

9400 W



Principle of Operation 1/3Principle of Operation 1/3

Noise Source+

Attenuator



Principle of Operation 2/3Principle of Operation 2/3

1

Switch Isolators

2

LNA

Receiver

0 1

2

Px

02

01

M0,crio

Noise Source

Ta–TH

77 K

7mm-K

M0,x

HP 8971C

HP 8970B

Pad 3dB

Att. Step 1dB

Att. Step 10dB

Cold Load

IF 20 MHz

Power Meter

PA

PA

IF

6 dB

isoe

crio

x

x,

crio,acrioax T

Y

Y

M

MTTTT

1

1

020

010

Vector Correction



PicturesPictures•Coaxial1-18 GHz

•WR 2826.5-40 GHz

•WR 2233-50 GHz



Data AnalysisData Analysis

MatLabMatLab®® codes has been used to:codes has been used to:

Process spar of non insertable Adapter

Compute Mismatch and Available Gain

Instruments control and automatic data collection

Calculate ENR and associated Uncertainty



Uncertainty of the ResultUncertainty of the Result

'21

2 2 2

2 2 20.0045 1.72 0.74 1.87 K

transa

crio crio crio crioT S Tu T u T u T u T

2 2 22

2 2 2 218.0 1.83 8.68 23.5 30.9 K

hot hot hot hot hots a Y Su T u T u T u T u T

Uncertainty of VNA is dominant ( 0.045 dB - hp 8510C )

S par UncertaintyDepend on U(Tcryo)

S par Uncertainty



Results andResults andAssociated UncertaintyAssociated Uncertainty

ENR @ 290 K - HP 346 C

6,0

6,5

7,0

7,5

8,0

8,5

9,0

1 3 5 7 9 11 13 15 17

Freq [GHz]

[dB

]

Data Sheet

ENR @ 290 K - HP 346 C

6,0

6,5

7,0

7,5

8,0

8,5

9,0

1 3 5 7 9 11 13 15 17

Freq [GHz][d

B]

misurato

U(ENR) was +/- 0.15 dB U(ENR) = +/- 0.06 dB



Spin-off for the LNAs Spin-off for the LNAs

80

100

120

140

18 20 22 24 26Frequency [ GHz ]

No

ise

Tem

per

atu

re [

K ] Simulation

80

100

120

140

18 20 22 24 26Frequency [ GHz ]

No

ise

Tem

per

atu

re [

K ] Simulation

Common U(ENR)

80

100

120

140

18 20 22 24 26Frequency [ GHz ]

No

ise

Tem

per

atu

re [

K ]

Simulation

Common U(ENR)

Low U(ENR)



WHAT can we do ? 1/3WHAT can we do ? 1/3

• No possibility to further reduce ENR Uncertainty

• … but we may transfer our expertise to reduce ENR Uncertainty of other Noise Sources

•REQUEST and submit a PROPOSAL

• Need to share expensive Instruments (CryoLoad)



WHAT can we do ? 2/3WHAT can we do ? 2/3• PROPOSAL: Comparition of Noise Figure Measurementover community (better if even larger)

• As the IEEE “Round Robin”, an LNA will be sentto European Laboratories to be measured.Each laboratory will perform measurement asusual and according to its own methodology

•Measured data will be compared and published



WHAT can we do ? 3/3WHAT can we do ? 3/3

• LNA Bandwidth has been chosen to be a bridge between the “easy” 1-18 GHz and the “difficult”over 18 GHz.

• Freq. 16 – 26 GHz,Gain=27dB,NF=1.6 dB (130K)

LNA

Power Supply

Euro Plug



Essential BibliographyEssential Bibliography• [1] J. Randa, “Noise Temperature Measurements on wafer ” NIST Tech. Note 1390 03/1997

• [2] Agilent Technologies, “Noise Figure measurement accuracy – The Y-Factor method”, Application Note 57-2, 2001.

•[3] W.C. Daywitt, “Radiometer equation and analysis of systematic errors for the NIST automated radiometers”, National Institute of Standards and Technology, Technical Note 1327, 03/1989.

•[4] C.T. Stelzried, “Temperature calibration of microwave thermal noise sources”, IEEE Transactions on Microwave Theory and Techniques (Correspondence), Vol. MTT-13, No. 1, 01/1965, pp. 128-130.

•[5] R.F. Bauer, P. Penfield, “De-Embedding and Unterminating”, IEEE Transactions on Microwave Theory and Techniques, Vol. 22, No. 3, 03/1974, pp. 282-288.

• [6] J.D. Gallego, “Accuracy of Noise Temperature Measurement of Cryogenic Amplifiers”, - NRAO Int. Rep. No 285 jan. 1990.



ConclusionsConclusions• The ENR of some Noise Sources has been calibrated.

• The Uncertainty related to ENR has been reduced from +/-0.15 dB typ to

+/- 0.06 dB typ

•The calibration routine and the instrumental set-up may be repeated once again.

•Waveguide, millimeter cryoloads are needed to improve reliability



ThanksThanks

sergio mariotti [email protected] göteborg, jun 19 th 2006 institute of radioastronomy, -...

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