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Measurement of Noise Figure of Quasi-optical power combiner

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July 99Noise Figure of power combiner2 Spatial Power Combiner System N-way power divider N-way power combiner High gain MMIC Low reflection matching V 1in MMIC Gain-G1 Noise Figure- NF1 V 1out Features V in V out

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July 99Noise Figure of power combiner3 Power Combiner simple model V Nout (G1) Low reflection Matching Single MMIC 50 N*50 N V 1in Single MMIC 50 N*50 V Nin (G1) Low reflection Matching Low reflection Matching Low reflection Matching 50 N*50 V 1out R=50

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July 99Noise Figure of power combiner4 V in = V 1in =…=V nin P in =N * P 1in =...= N * P Nin V out = V 1out =…=V nout P out =N * P 1out =...= N * P Nout The total Gain G t is the same as G 1 Theoretical Analysis

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July 99Noise Figure of power combiner5 Singal MMIC: Noise Figure of power combiner Power Combiner : V Nout (G1, NF1) Low reflection Matching 50 N*50 N V 1in 50 N*50 V Nin (G1, NF1) Low reflection Matching Low reflection Matching Low reflection Matching 50 N*50 V 1out N add (G1, NF1) Added Noise by MMIC N add

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July 99Noise Figure of power combiner6 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. V Nout V 1out N N*R R

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July 99Noise Figure of power combiner7 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. Vn Nout Vn 1out N N*R R Vn out

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July 99Noise Figure of power combiner8 Ideal Power Combiner: Real System Noise Figure Real Power Combiner : V Nout (G1, NF1) Low reflection Matching 50 N*50 N V 1in 50 N*50 V Nin (G1, NF1) Low reflection Matching Low reflection Matching Low reflection Matching 50 N*50 V 1out N add (G1, NF1) Insertion Loss L1 L1

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July 99Noise Figure of power combiner9 Measurement System Noise Figure Meter-8970B CW Generator-8673G Output power-8dBm Test Set-8971B Working Mode:SSB3 From 4-18GHz Down Convert to 450MHz Single Side Band Noise Noise Source Driver Noise Source - 346C Noise Input LO Signal Input

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July 99Noise Figure of power combiner10 Single MMIC Measurement Biase For MMIC Microstrip Probe Noise Output Noise Input MMIC

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July 99Noise Figure of power combiner11 Power Combiner Measurement Bias For MMICs Noise Source Driver Input Noise Output Noise Input Noise Source Power Combiner Heat Sink

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July 99Noise Figure of power combiner12 Measurement Theory T1T2 Noise Temperature-T Output Noise Power No N1 N2 Na 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

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July 99Noise Figure of power combiner13 Measurement Result @Vd=7V

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July 99Noise Figure of power combiner14 Measurement Result Plot @Vd=7V

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July 99Noise Figure of power combiner15 Measurement Result Plot @Vd=6V

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July 99Noise Figure of power combiner16 Measurement Result Plot @Vd=5V

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July 99Noise Figure of power combiner17 Summary The measurement result show that the Noise Figure of Power Combiner is the same as one single MMIC.

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