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# PHASE & AMPLITUDE STABILITY STUDY OF 200MHz T0 800MHz LNA FOR GMRT - PowerPoint PPT Presentation

PHASE & AMPLITUDE STABILITY STUDY OF 200MHz T0 800MHz LNA FOR GMRT. by ARNAB MANDAL [email protected] UNDER GUIDENCE OF Mr. A.Praveen Kumar. OUTLINE OF THE TALK. Introduction Basics of amplifier Noise measurement Theoretical calculation

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### PHASE & AMPLITUDE STABILITY STUDY OF 200MHz T0 800MHz LNA FOR GMRT

by

ARNAB MANDAL

[email protected]

UNDER GUIDENCE OF

Mr. A.Praveen Kumar

OUTLINE OF THE TALK FOR GMRT

• Introduction

• Basics of amplifier

• Noise measurement

• Theoretical calculation

• Data acquisition

• Plot by MATLAB

• Analysis of graph

• Further improvement

INTRODUCTION FOR GMRT

• Determination of imbalance of the two LNA's

• Study of gain ratio

• Study of phase change

BASICS OF AMPLIFIER FOR GMRT

• Gain

G (dB) =10log (Pout/Pin)

=20log (Vout/Vin)

BASICS OF AMPLIFIER FOR GMRT

• Noise

Noise figure:

F= SNRin/SNRout

=PNout/PNin

Noise figure:

F=10log(NF)

BASICS OF AMPLIFIER FOR GMRT

Friis' formula

Noise temperature

Friis formula for noise temperature

NOISE MEASUREMENT FOR GMRT

• By Noise figure analyzer

NOISE MEASUREMENT FOR GMRT

• Optimization of gain

Gain approximately 26db

Noise temperature below 40 Kelvin

THEORETICAL CALCULATION FOR GMRT

• Block diagram with LNA

SIGNAL GENAR-ATOR

VECTOR

VOLT-

METRE

LAPTOP

3DB SPLITTER

LNA1

LNA2

THEORETICAL CALCULATION FOR GMRT

• After 3db splitter

X1=X *A1 *ej1

X2=X*A2 *ej2

• After LNAs

X3 =X1 *G1 *ej1

X4=X2 *G2 *ej2

|B/A|=[G2 *ACABLE 2 *A CHANNEL 2]/[G1*ACABLE 1 *A CHANNEL 1]

Phase part:

B-A= (Phase change) LNA+ (Phase change) SPLITTER

+(Phase change) CABLE

SIGNAL GENAR-ATOR FOR GMRT

VECTOR

VOLT-

METRE

LAPTOP

3DB SPLITTER

THEORETICAL CALCULATION

• Block diagram without LNA

THEORETICAL CALCULATION FOR GMRT

• Experiment without LNAs gives the

(B’/A’ )WITHOUT LNA

&

B’-A’=(Phase change)SPLITTER+ (Phase change)CABLE

DATA ACQUISITION FOR GMRT

• Done by LABVIEW program

Total time taken=15*900*13 seconds

=175500 seconds

=48.75 hours.

Data was taken for 48.75 hours

PLOT BY MATLAB FOR GMRT

• Figure 1

PLOT BY MATLAB FOR GMRT

• Figure 2

PLOT BY MATLAB FOR GMRT

• Figure 3

PLOT BY MATLAB FOR GMRT

• Figure 4

PLOT BY MATLAB FOR GMRT

• Figure 5

PLOT BY MATLAB FOR GMRT

• Figure 6

2 FOR GMRTnd EXPERIMENT

Experiment: 1 Experiment: 2

2 FOR GMRTnd EXPERIMENT

Experiment: 1 Experiment: 2

FURTHER IMPROVEMENT FOR GMRT

• Reduction of cable losses

• Cause of gain difference

• Measurement error

Thank You FOR GMRT