2 Circuits à diodes

Si
Si
B
B
Si
Si
Si
B
Si
Si
As
Si
Si
Si
As
As
Si
Si
Semi-conducteur p Semi-conducteur n
ID
UD

ID=ISexp UD
nVT−1
VTkT q
VT=kT
q'26 @ T= 300
k1.38·10−23 /oq
1.6·10−19
IS
n
IS
(' −1 )
ID' −IS
ID=−IS'0UD<−0.3
UD>0.3
ID=ISexp UD
nVTUD>+0.3
ID= 1
ID= 100

−0.5 −0.4 −0.3 −0.2 −0.1 0 0.1
−1
−0.5
0
0.5
1
1.5
2
ID [nA]
Polarisation inverse
−0.2 −0.1 0 0.1 0.2
0
20
40
60
80
100
ID [nA]
Faible tension
0 0.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
ID [mA]
UD [V]
Faibles courants
0 0.2 0.4 0.6 0.8 1
0
20
40
60
80
100
ID [mA]
UD [V]
Forts courants
0 0.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
UD [V]
ID [mA]
Faibles courants
0 0.2 0.4 0.6 0.8 1
0
20
40
60
80
100
UD [V]
ID [mA]
Forts courants
Ug=R ID+UDUD=n VTID
IS
+ 1

UD'0.6ID'1UD'0.8ID'100
UD=Vj'0.7
ID
R
UgUD
ID
UD
ID
UD = Vj
∆ID
∆UD = rd ∆ID
rd
ID=Ug−Vj
R
UD
Vj
dID
dUDUD=Vj
=
dISeUD/(nVT)
dUDUD=Vj
=ID
nVT
rd
UDID
rd≡∆UD
∆ID
=nVT
ID
Vj
∆UD=rd∆ID
Ug= 5 , R = 100 Ω

IDVj= 0.7
ID=Ug−Vj
R=5−0.7 100 Ω = 43
n= 1.7
rd=nVT
ID
=1.7·26
43 '1 Ω
R
rdR
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
0
20
40
60
80
100
U [V]
I [mA]
diode
générateur
UD=Ug−R ID
ID=ISexp UD
nVT
UD= 0.77 , ID= 42
UD