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Series Editor

Robert Baptist

Noise in Radio-Frequency Electronics and its Measurement

François Fouquet

images

Preface

As a professor/researcher at ESIGELEC since 1982, I have been confronted with “noise in radiofrequency electronics” as part of my teaching activities, as also during my research work.

For my teaching activities, it was in the second half of the 1980s, that I created course materials, tutorials and practical work on this subject for students of ESIGELEC pursuing courses in the field of radiofrequencies and microwaves and for technicians and engineers working for companies in these fields.

As far as my research activities are concerned, my first “in-depth” contact with “electronic noise” dates back to the time of my DEA diploma and then my doctorate, when I had to quantify “by hand” the impact of the use of “active load polarization” on the noise factor of a “common gate MESFET”.

In both cases, I was confronted with the same problem: unsuitable bibliographic sources. The reason being either:

It is to fill a part of the gap that exists between these two worlds that I decided to write this document to summarize what I have essentially learned about noise during the last 40 years.

On this occasion, I would particularly like to thank Mr. J.L. Gautier and Mr. D. Pasquet who initiated me to study this subject during my DEA diploma studies and my doctorate, while they were professors at ENSEA.

I would also like to thank Mr. M. Rivette and Mr. J.B. Dioux, alumni of ESIGELEC, who inspired me to do this work while I was correcting their report on the noise figure of adapted attenuator.

François FOUQUET

November 2019

List of Symbols

* Conjugate operator on a complex, c = a + jb,c* = a — jb
ai Incident power wave on port i of a two-port, equal to at =images with images and images
bi Reflected power wave on port i of a two-port, equal to bi = imageswith images and images
bni Noise power wave outputted from port i of a two-port
BCor Imaginary part of the correlation admittance YCor, between e and i of normalized value bCor
BSopt Imaginary part of the optimal admittance for the YSopt noise, of normalized value bSopt
e Equivalent noise voltage source at the input of a two-port, see Figure 1.11
ENR Excess noise ratio of a noise source at two temperatures Tc (cold temperature) and TH (hot temperature), equal to ENR = imagesand expressed in dB: ENRdB = 10 · log10(ENR)
F Noise factor of a two-port, information on the degradation of the signal / noise ratio between the input and the output of the two-port, depends on the load presented at the input of the two-port, F >1
FeMin The minimum excess noise factor of a two-port, equal to FeMin = FMin – 1
FMin The minimum noise factor of a two-port, obtained for the optimal load for noise presented at the input of the two-port
Γsopt Optimum reflection coefficient for the noise to present at the input of the two-port to obtain F = FMin, equal to ΓSopt = images
GAvai(Ys) Gain in Available power gain of a two-port for a source admittance Ys, equal to the value of the transducer power gain GT(YS, YL) for YL = Y*OUT
Gn Equivalent noise conductance at the input of a two-port, images of normalized value gn = Gn· R0
Gsopt Real part of the optimal admittance for the Ysopt noise, of normalized value gsopt
GT(YS, Yl) Transducic power gain of a two-port for a source admittance Ys and a load admittance YL, equal to the ratio of the power collected in YL and the power available at the source
G0 Normalization admittance equal to 1/R0or 20 mS
h Planck’s constant 6.23x10-34J s
i Equivalent noise current generator at the input of a two-port, see Figure 1.11
Im(c) “Imaginary part” operator on the complex c
in Equivalent noise current generator at the input of a two-port not correlated with e
i1 Noise current generator equivalent to the input of a two-port, see Figure 1.10
i2 Noise current generator equivalent to the input of a two-port, see Figure 1.10
j Square root of - 1 which allows to describe a complex in the form c = Re(c) + j · Im(c)
k Boltzmann’s constant 1.38×10-23 J K-1
NC Noise power measured at the output of a two-port when the noise source is at cold temperature Tc
NH Noise power measured at the output of a two-port when the noise source is at hot temperature TH
NF Noise Figure of a two-port, equal to 10 · log10(F), NF > 0dB
μn Electron mobility in cm2 s-1 V-1
P Power dissipated in a load Y, equal to Re(V · I*) with I = Y -V
PsAvai Available power of a source E,YS = Gs + jBs, equal to images
Re(c) “Real part” operator on the complex c
RN Equivalent noise resistance at the input of a two-port, images = 4kT · df · RN , of normalized value images
R0 Normalization resistance equal to 50 Ω
Sij S parameters of a two-port of ports i,j
T Temperature in K
Te Equivalent noise temperature of a two-port equal to Te = T0 · (F — 1), expressed in K
TeMin Equivalent minimum noise temperature of a two-port equal to TeMin = T0 · (FMin — 1) , expressed in K
T0 Reference temperature for the noise factor equal to 290 K
Y “Y” factor, used by the measurement of the factor, equal to images
YCor Correlation admittance between e and i, defined by i = YCor · images
Yij Admittance parameters of a two-port of ports i, j
Ysopt Optimum Admittance for the noise to present at the input of the two-port to obtain F = FMin, of normalized value ySopt