INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Reduction of the Uncertainty
on Noise Figure Measurements
A. Cremonini 1, M. De Dominicis 2, S. Mariotti 1 , E. Limiti 3, A.Serino 3
1
2
3
INAF – Institute of Radioastronomy- Bologna – Italy
Elettronica s.p.a. – V. Tiburtina Valeria, Rome – Italy
University “Tor Vergata” – Electronic Eng. Dept. – Rome - Italy
Sergio Mariotti s.mariotti@ira.inaf.it
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
WHY
Reduce Uncertainty?
Noise Figure
+/- 3.5
%
=
+/-
0.15 dB
RF Impedance
5E-03
5E-07
Voltage
Time
For a receiver:
NF = 0.3 +/-0.15 1.E-14
dB
Te = 21 +/- 11 K
3.5E-02
1E-13
1.E-12
1.E-10
1.E-08
1.E-06
1.E-04
1.E-02
1.E+00
Absolute Uncertainty
Uncertainty should be much lower than the value to be measured
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
How
Reduce Uncertainty?
•
Looking for and Find Sources of Uncertainty (U)
•
Minimize the sources wherever it is possible
•
Analyze and propagate uncertainty
•
Since U(ENR) is dominant, let do calibration of Noise
Source with a Secondary Standard (liq. N2)
•
Let Practical operations accurate as possible
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Involved Environments
Room Temperature
- easier
- faster
- accurate
Cryogenic /on Dewar
- less jitter
- more realistic
- accurate
Sergio Mariotti
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Sources (causes) of Uncertainty:
Propagation, Math Formulation
F12
F1 = 3 dB
G1= 15 dB
F2 = 10dB
2
F2  1
F12  F1 
G1
2
F 
 F 
uc2  NF1    12  u 2  NF12    2  u 2  NF2  
 F1 
 F1G1 
uc  NF1    0.112  0.022  0.0772  0.0982  0.167 dB
2
2
 F  1  2 dB  F12
F2  2
dB
 2
u
G






 u  ENR 
1
 F1G1 
 F1 F1G1 
•Depend on many causes, even U(ENR)
Depend on U(ENR)
Sergio Mariotti
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Causes of Uncertainty:
Graphical - Intuitive
Ph
P
Pcc
Te
Tc Tc
Th
Reducing Tc, will reduce U(Te)
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
Sergio Mariotti
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Causes of Uncertainty:
Practical, Tips&Tricks
|S11 ON| , |S11 OFF| < - 33 dB
Selected Attenuator
PT 100 A
6 dB
Cascade Ferrite Isolators
Precision Connectors / Connector Care
NO cables movement
Environment: Thermostatic room,
Type A Uncert. << Type B Uncert.
Sergio Mariotti
th
Göteborg, jun 19 2006
10 dB
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Other causes of Uncertainty:
Mismatch: A closed form expression doesn’t exist
Approximate Expression
1
Te
1
1  290 T e
2
 NS   DUT
NS
+/-  Te [oK ]
100.0
DUT
10.0
1.0
0.1
0
10
20
30
40
50
R.L. NoiseSource + R.L. DUT [dB ]
Sergio Mariotti
th
Göteborg, jun 19 2006
60
70
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Principle of Operation 1/3
3200
9400
800 mW
mW
Liq. N2
77 K
POWER METER
Noise Source
+
Attenuator
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Principle of Operation 2/3
Tx  Ta  Tcrio
M0,crio 01 Yx  1
 Ta 
 Te iso
M0, x 02 Ycrio  1
Vector Correction
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Pictures
•Coaxial
1-18 GHz
•WR 28
26.5-40 GHz
•WR 22
33-50 GHz
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Data Analysis
MatLab® 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
Sergio Mariotti
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
u Thot  

Uncertainty of the Result
 u  T     u T     u T     u T  
2
2
hot s
2
hot a
hot Y
hot S
2

18.0  1.83  8.68   23.5  30.9 K
2
2
2
2
Depend on U(Tcryo)
S par Uncertainty
u Tcrio   u Tcrio T  u Tcrio  S trans  u Tcrio T ' 
2
2
a

21
 0.0045  1.72    0.74 
2
2
2
2
 1.87 K
S par Uncertainty
Uncertainty of VNA is dominant
Sergio Mariotti
( 0.045 dB - hp 8510C )
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Results and
Associated Uncertainty
ENR @ 290 K - HP 346 C
ENR @ 290 K - HP 346 C
misurato
9,0
9,0
8,5
8,5
8,0
8,0
[dB]
[dB]
Data Sheet
7,5
7,5
7,0
7,0
6,5
6,5
6,0
6,0
1
3
5
7
9
11
13
15
17
1
5
7
9
11
13
15
17
Freq [GHz]
Freq [GHz]
U(ENR) was +/- 0.15 dB
3
U(ENR) = +/- 0.06 dB
Sergio Mariotti
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Noise Temperature [ K ]
Spin-off for the LNAs
140
Simulation
Simulation
Common
U(ENR)
Simulation
Common
U(ENR)
Low
U(ENR)
120
100
80
18
20
20
22
22
24
24
26
26
Frequency [ GHz ]
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
WHAT 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)
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
WHAT can we do ?
2/3
• PROPOSAL:
Comparition of Noise Figure Measurement
over
community (better if even larger)
• As the IEEE “Round Robin”, an LNA will be sent
to European Laboratories to be measured.
Each laboratory will perform measurement as
usual and according to its own methodology
•Measured data will be compared and published
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
WHAT can we do ?
• LNA Bandwidth has
been chosen to be a
bridge between the
“easy” 1-18 GHz and
the “difficult”
over 18 GHz.
3/3
Euro Plug
Power Supply
LNA
• Freq. 16 – 26 GHz,
Gain=27dB,
NF=1.6 dB (130K)
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Essential 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.
Sergio Mariotti
th
Göteborg, jun 19 2006
INSTITUTE OF RADIOASTRONOMY, - ITALY
UNIVERSITY “TOR VERGATA” - ROME
Conclusions
• 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
•Waveguide, millimeter cryoloads are needed to improve reliability
•The calibration routine and the instrumental set-up may be repeated
once again.
Sergio Mariotti
th
Göteborg, jun 19 2006
UNIVERSITY “TOR VERGATA” - ROME
INSTITUTE OF RADIOASTRONOMY, - ITALY
Thanks
Sergio Mariotti
th
Göteborg, jun 19 2006