Transcript Noise Immunity Analysis of Forward Hadron Calorimeter Front-end Electronics. Authors

Noise Immunity Analysis of
Forward Hadron Calorimeter
Front-end Electronics.
Authors
C. Rivetta– Fermilab.
F. Arteche , F. Szoncso, - CERN
OUTLINE
 1- Introduction
2-Noise considerations
3-Thermal noise
4-Multi-transmission line model
5-Surface transfer impedance
6-Common mode rejection
–Examples
7-External electromagnetic field
–Examples
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1.INTRODUCTION
 The goal of this study is to establish the susceptibility
level to electromagnetic noise of the HF CMS
calorimeter.
 Characterise the influence of topology and parameters
on the overall FEE noise
– Thermal Noise
– Conductive Common Mode (CM) Noise
– Electromagnetic Interference (EMI)
 Generate a software tool to assist:
– The analysis of cable quality.
– Analysis of common mode effects on sensitive equipment.
 Conducting & radiated coupling through cables.
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1.INTRODUCTION
Dy7
Dy8
QIE sig.
Anode
PMT
Cc
HV
QIE ref.
Rgnd
 PMTs / QIE distance is 4 meters.
 QIE:Sample Charge integrator with ADC
 QIE is a differential current mode amplifier.
 QIE input impedance 50 or 93 Ohms.
 Asymmetric dynamic range.
 Gain: 1fC/LSB
 Sampling freq.: 40MHz.
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2. NOISE CONSIDERATIONS
 Low level signal processing of FEE is defined by the noise
n(t )  s (t )
 Noise at output is composed by several factors
na (t )  nth(t )  nCM (t )  nEMI (t )  .....
–Power Spectrum nth(t)
Nth2 ( )  Tv( ) .en 2 ( )  Ti ( ) .in 2 ( )
2
2
nCM(t) and nEMI(t) in frequency domain
Ncm( )  TCM ( ).TAMP( ).VCM ( )
NEMI ( )  (TEMIH ( ).H ( )  TEMIE ( ).E ( )).TAMP( )
•Criteria generally used na 2  nth 2 ;
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(nCM  nEMI  ... ) 2  0
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3. THERMAL NOISE
2
n
e
G f 
in2

va
Zo
1 
va (t )   g (t ) * i (t )  i (t ) .dt
C 0
1  e  s. G( s)  ( I  ( s)  I  ( s))
va ( s) 

 TAMP( s)  ( I  ( s)  I  ( s)) ;
s
C
I  ( ); I  ( ) 
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en( )
in( ).Zin

( Zin  Zo) ( Zin  Zo)
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3. THERMAL NOISE
ENC


G 2  en2
w 

2 


i

if


L

n

 4
C 2  Z 0 2
2

2

 nth 
 2  2


 G   en  in2   L  in2 .   if   L  w 
 2.v
 C 2  Z 0 2
2
2





ENC 
2
Cable
No
Yes
Yes
L
 Cables with low impedance increse the
thermal noise
 There exists a critical length for the cable
where the noise does not increase.
 nth 2 
G
 
C
 . / 2.
2
Length
5 mts
5 mts
Zo
50
93
ENC- QIE
3500e11000e7000e-
 Measured by T. Zimmermann, Fermilab
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3. MULTI-CONDUCTOR TRANSMISSION
LINE MODEL
 TEM mode
 R,L,C,G line
parameter matrices
per unit length
 V,I voltage &
currents vectors
 Solution:
– Terminal Boundary
conditions
– Frequency domain
– Time domain


V ( z, t )   R I ( z, t )  L I ( z, t )
z
t


I ( z , t )  GV ( z , t )  C V ( z , t )
z
t
V2 ( z  Dz , t )
I1 ( z , t )
V1 ( z , t )
I1 ( z  Dz , t )
I2 ( z , t )
I 2 ( z  Dz , t )
I3 ( z , t )
I 3 ( z  Dz , t )
I 3 ( z  Dz , t )
V2 ( z , t )
..
..
V2 ( z , t )
.
V3 ( z  Dz , t )
I 3 ( z  Dz , t )
.
I n ( z  Dz , t )
In ( z , t )
Vn ( z , t )
Vn ( z  Dz , t )
I 3 ( z  Dz , t )
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4. SURFACE TRANSFER IMPEDANCE
Vt
Zt(w)=Vt(w)/I(w)
I
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4. SURFACE TRANSFER IMPEDANCE
Inner System
I2
I0* Zt2
I1
R2
L2
R1
L1
I0* Zt1
V2
C20
V1
Inner Conductors
C12
U0* Yt2
U0* Yt1
C10
Shield
I0
RS
LS
V0
CS0
Outer System
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Shield
Environment
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4. SURFACE TRANSFER IMPEDANCE
Zt  Zd ( )  j.( Mh  Mb )
Zd (w ) Diffusion coupling due to skin effect (LF)
– Mh - Aperture coupling (HF)
– Mb - Braid inductance (HF)
 Define the amount of noise coupled to the internal
conductors
 It is a characteristic parameter of shielding cable


V ( z , t )   R I ( z, t )  L I ( z , t )  Zt.Io( z , t )
z
t


I ( z , t )  GV ( z, t )  C V ( z, t )  Yt .Vo( z, t )
z
t
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4. COMMON MODE REJECTION
PMT
QIE sig.
Cp
Cc
QIE ref.
Rgnd
Vcm
 Rgnd : 100ohms, 1Kohms, 10Kohms
 Cp -Parasitic capacitance of PMT, board and connections
 Cc- Compensation capacitance
 Coaxial cable RG-58
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4. COMMON MODE REJECTION
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4. COMMON MODE REJECTION
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4. COMMON MODE REJECTION
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5. EXTERNAL ELECTROMAGNETIC FIELD
 External magnetic field
– Voltage generator (VF)
 External electric field
– Current generator (IF)
 VF, IF are dependent of
system geometry.
 Applicable for near
fields & far fields -weak


coupling.
V  z , t   L I  z , t   R I  z , t   VF  z , t 
z
t
 Example:


I z, t   C V z, t   G V z, t   I F z, t 
z
t
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– Far-field, E=100uV/m
 (EN 55022 A)
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5. EXTERNAL ELECTROMAGNETIC FIELD
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5. EXTERNAL ELECTROMAGNETIC FIELD
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5. FUTURE WORKS
 Final conclusions about sensitivity to CM and EM
interference
 Extend the analysis to different HF cable prototypes.
 Include studies of near fields
– Electric field
– Magnetic field
 Extend to time domain solutions
– Transient effects
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5. CONCLUSIONS
 The analysis allows to quantify effects of parasitic
elements and unbalances on HF configuration.
 The system is very sensitive to parasitic elements that
unbalance the differential topology
– Proper selection of final cable
– Influence of Rgnd is important at low frequency
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