# Measurement of Noise Figure of Quasi-optical power combiner.

## Presentation on theme: "Measurement of Noise Figure of Quasi-optical power combiner."— Presentation transcript:

Measurement of Noise Figure of Quasi-optical power combiner

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

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 

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

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

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

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

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

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

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

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

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

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

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

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

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

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.