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Measurement of Noise Figure of Quasi-optical power combiner. Spatial Power Combiner System. Features. N-way power divider N-way power combiner High gain MMIC. MMIC Gain-G1 Noise Figure- NF1. V out. V 1out. Low reflection matching. V in. V 1in. Power Combiner simple model.
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Spatial Power Combiner System Features • N-way power divider • N-way power combiner • High gain MMIC MMIC Gain-G1 Noise Figure- NF1 Vout V1out Low reflection matching Vin V1in Noise Figure of power combiner
Power Combiner simple model Single MMIC (G1) V1in V1out Low reflection Matching Low reflection Matching 50 50 N*50 N*50 N Single MMIC (G1) VNin VNout Low reflection Matching Low reflection Matching R=50 N*50 50 50 N*50 Noise Figure of power combiner
Theoretical Analysis • 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 Noise Figure of power combiner
Noise Figure of power combiner Added Noise by MMIC Nadd Singal MMIC: (G1, NF1) Nadd V1in V1out (G1, NF1) Low reflection Matching Low reflection Matching Power Combiner : 50 50 N*50 N*50 N Nadd VNin VNout (G1, NF1) Low reflection Matching Low reflection Matching N*50 50 50 N*50 Noise Figure of power combiner
V1out N*R N R VNout N*R 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. Noise Figure of power combiner
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. Vn1out N*R Vnout N R VnNout N*R 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. Noise Figure of power combiner
Real System Noise Figure Ideal Power Combiner: (G1, NF1) Nadd Insertion Loss L1 Real Power Combiner : V1in V1out (G1, NF1) Low reflection Matching Low reflection Matching 50 50 N*50 N*50 N Nadd Insertion Loss L1 VNin VNout (G1, NF1) Low reflection Matching Low reflection Matching N*50 50 50 N*50 Noise Figure of power combiner
Measurement System Noise Figure Meter-8970B Noise Source Driver CW Generator-8673G Output power-8dBm Noise Source - 346C Noise Input LO Signal Input Test Set-8971B Working Mode:SSB3 From 4-18GHz Down Convert to 450MHz Single Side Band Noise Noise Figure of power combiner
Single MMIC Measurement Microstrip Probe Biase For MMIC Noise Output Noise Input MMIC Noise Figure of power combiner
Power Combiner Measurement Bias For MMICs Noise Source Driver Input Noise Input Noise Source Noise Output Power Combiner Heat Sink Noise Figure of power combiner
Measurement Theory Output Noise Power No • 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 N2 N1 Na Noise Temperature-T T1 T2 Noise Figure of power combiner
Measurement Result @Vd=7V Noise Figure of power combiner
Measurement Result Plot @Vd=7V Noise Figure of power combiner
Measurement Result Plot @Vd=6V Noise Figure of power combiner
Measurement Result Plot @Vd=5V Noise Figure of power combiner
Summary • The measurement result show that the Noise Figure of Power Combiner is the same as one single MMIC. Noise Figure of power combiner