Measurement of Noise Figure of Quasi-optical power combiner

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


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



50N*50

N*50

V1out

PinVin

R

2

R=50

PoutVout

R

2


• 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


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)




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


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


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


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)




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


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


Single MMIC MeasurementSingle MMIC Measurement

Biase For MMICBiase For MMICMicrostrip ProbeMicrostrip Probe

Noise OutputNoise OutputNoise InputNoise Input

MMICMMIC


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


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


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


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)



0

5

10

15

20

25

0

5

10

15

20

25

8 8.5 9 9.5 10 10.5 11


G1(dB)GtdB)




0

5

10

15

20

25

0

5

10

15

20

25

8 8.5 9 9.5 10 10.5 11


G1(dB)GtdB)



SummarySummary

• The measurement result show that the Noise Figure of

Power Combiner is the same as one single MMIC.

Measurement of Noise Figure of Quasi-optical power combiner

Documents

mafetnc state reviewhow

mmics of power combiner

real power combiner

goutput power

nf1added noise

added noise of single

different noise temperatureget

n times covariance