measurement of noise figure of quasi-optical power combiner
TRANSCRIPT
Measurement of Noise Measurement of Noise Figure of Quasi-optical Figure of Quasi-optical
power combinerpower combiner
July 99 Noise Figure of power combiner 2
Spatial Power Combiner SystemSpatial Power Combiner System
• N-way power divider
• N-way power combiner
• High gain MMIC
Low reflection matching
V1in
MMICGain-G1
Noise Figure- NF1 V1out
Features
Vin
Vout
July 99 Noise Figure of power combiner 3
Power Combiner simple modelPower Combiner simple model
VNout
(G1)Low
reflectionMatching
Single MMIC
50N*50
N
V1in
Single MMIC
50 50N*50
VNin
(G1)
Low reflectionMatching
Low reflectionMatching
Low reflectionMatching
50N*50
N*50
V1out
PinVin
R
2
R=50
PoutVout
R
2
July 99 Noise Figure of power combiner 4
• Vin= V1in =…=Vnin
• Pin=N * P1in =...= N * PNin
• Vout= V1out =…=Vnout
• Pout=N * P1out =...= N * PNout
• The total Gain Gt is the same as G1
Theoretical AnalysisTheoretical Analysis
PV
Rinin
2
PV
N Rinin
1
2
*
R50
PV
Routout
2
PV
N Routout
1
2
*
GP
Pout
in1
1
1
GP
Ptout
in
July 99 Noise Figure of power combiner 5
Singal MMIC:
Noise Figure of power combinerNoise Figure of power combiner
Power Combiner :
VNout
(G1, NF1)Low reflectionMatching
50N*50
N
V1in
50 50N*50
VNin (G1, NF1)
Low reflectionMatching
Low reflectionMatching
Low reflectionMatching
50N*50
N*50
V1out
Nadd
Nadd
NFS N
S N
N
G N
NFG N N
G N
T
T
i i
o o
o
i
i add
i
e
o
11
11
1
1
/
/
NFS N
S N
N
G N
NFG N N
G N
T
T
G G N N N N
ti i
o o
ot
t it
tt it addt
t it
e
o
t it i addt add
/
/
( ; ; )
1
1
(G1, NF1)
Added Noise by MMIC
Nadd
N kT Bi o4 No
N kT Bit o4 Not
July 99 Noise Figure of power combiner 6
Why they are the same?Why they are the same?
• The reason is that the combining of irrelevant N channel noise is the same as one channel.
• That is Nadd=Naddt
Notice: The power combiner is not a linear amplitude summing network, but works as a spatial power summing system.
VNout
V1out
N
N*R
N*R
R
VV
N
V
Noutout out 1 1
July 99 Noise Figure of power combiner 7
How the noise is added?How the noise is added?
• The noise is evaluated with covariance.• The covariance of the sum of N irrelevant variables are N times
covariance of each variable.
Considering only the added noise by MMICs: The added noise by MMICs of power combiner is the same as the added noise of single MMIC.
VnNout
Vn1out
N
N*R
N*R
R
VnVn
N
Vn
Noutout out 1 1
NVn
N R
Vn Vn
N R
addout
out out
12
1 12
*
[ ]
*
Nadd
Naddt
NVn
R
NVnNR
Vn
N RN
addtout
out
outadd
2
1 2
12
[ ]
*
Nadd
Vnout
July 99 Noise Figure of power combiner 8
Ideal Power Combiner:
Real System Noise FigureReal System Noise Figure
Real Power Combiner :
VNout
(G1, NF1)Low reflectionMatching
50N*50
N
V1in
50 50N*50
VNin (G1, NF1)
Low reflectionMatching
Low reflectionMatching
Low reflectionMatching
50N*50
N*50
V1out
Nadd
Nadd
G G
NFT
TNF
t
e
ot
1
1 1
NFG N N L
G N
T
T
G
G
tt it add
t it
e
o t
1
11
21 ( )
(G1, NF1)
N kT Bi o4N G N N
k G T T Bo i add
o e
1
14 ( )
N kT Bit o4Not
Insertion LossInsertion LossL1L1
Insertion LossInsertion LossL1L1
G G LG
Gtt 1 11
1
2; ( )
N k G T Badd e 4 1
Nit
July 99 Noise Figure of power combiner 9
Measurement SystemMeasurement System
Noise Figure Meter-8970BNoise Figure Meter-8970B
CW Generator-8673GCW Generator-8673GOutput power-8dBmOutput power-8dBm
Test Set-8971BTest Set-8971BWorking Mode:SSB3Working Mode:SSB3
From 4-18GHzFrom 4-18GHzDown Convert to Down Convert to
450MHz450MHzSingle Side Band NoiseSingle Side Band Noise
Noise Source DriverNoise Source Driver
Noise Source - 346CNoise Source - 346C
Noise InputNoise InputLO Signal InputLO Signal Input
July 99 Noise Figure of power combiner 10
Single MMIC MeasurementSingle MMIC Measurement
Biase For MMICBiase For MMICMicrostrip ProbeMicrostrip Probe
Noise OutputNoise OutputNoise InputNoise Input
MMICMMIC
July 99 Noise Figure of power combiner 11
Power Combiner MeasurementPower Combiner Measurement
Bias For MMICsBias For MMICsNoise Source Driver InputNoise Source Driver Input
Noise OutputNoise Output
Noise InputNoise Input
Noise SourceNoise Source
Power CombinerPower Combiner
Heat SinkHeat Sink
July 99 Noise Figure of power combiner 12
Measurement TheoryMeasurement Theory
T1 T2 Noise Temperature-TNoise Temperature-T
OutputOutput
Noise PowerNoise Power
NoNo
N1
N2
Na
GdN
dT 0
• The Noise Figure Meter output noise at two different noise temperature
• Get the G and Na from the measurement
• Calibrate to eliminate the affect of the loss of the cable and connectors
July 99 Noise Figure of power combiner 13
Measurement Result @Vd=7VMeasurement Result @Vd=7V
1MMIC 2*2 array 2*2 arrayVg=5V Ig=0.06A Vg=5V Ig=0.36AVd=7V Id=1.05A Vd=7V Id=2.79A
Freq(GHz) G1(dB) NF1(dB) Gt(dB) NFt(dB) NFt*(dB)8 20.67 6.27 19.14 7.07 6.866195
8.25 20.95 6.38 19.6 6.89 6.9086868.5 21.37 6.25 20.28 6.64 6.67181
8.75 21.3 6.04 19.95 6.54 6.5565519 21.37 5.98 20 7.04 6.502066
9.25 20.54 5.95 20.1 6.65 6.1151469.5 19.95 5.75 20.12 6.53 5.687779
9.75 19.3 5.45 19.56 6.03 5.35746110 18.85 5.4 18.17 5.93 5.644644
10.25 18.46 5.29 18.19 5.75 5.38550210.5 17.43 5.22 18.03 5.53 5.012381
10.75 17.52 5.05 17.02 5.55 5.22338311 16.59 4.95 16.38 5.27 5.021687
NFT
T
G
G
T NF T
te
o t
e o
* ( )
( )*
1
1
11
2
1
July 99 Noise Figure of power combiner 14
Measurement Result Plot @Vd=7VMeasurement Result Plot @Vd=7V
0
5
10
15
20
25
0
5
10
15
20
25
8 8.5 9 9.5 10 10.5 11
Noise Figure & Gain at Vd=7V
G1(dB)GtdB)
NF1(dB)NFt(dB)NFt*(dB)
Freq(GHz)
July 99 Noise Figure of power combiner 15
Measurement Result Plot @Vd=6VMeasurement Result Plot @Vd=6V
0
5
10
15
20
25
0
5
10
15
20
25
8 8.5 9 9.5 10 10.5 11
Noise Figure & Gain at Vd=6V
G1(dB)GtdB)
NF1(dB)NFt(dB)NFt*(dB)
July 99 Noise Figure of power combiner 16
Measurement Result Plot @Vd=5VMeasurement Result Plot @Vd=5V
0
5
10
15
20
25
0
5
10
15
20
25
8 8.5 9 9.5 10 10.5 11
Noise Figure & Gain at Vd=5V
G1(dB)GtdB)
NF1(dB)NFt(dB)NFt*(dB)
July 99 Noise Figure of power combiner 17
SummarySummary
• The measurement result show that the Noise Figure of
Power Combiner is the same as one single MMIC.