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© Robert York, 20062007
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Temperature Dependence
//
1
dd
T
qV
nkT
V
nV
ss
II
e
I
e
ln
dT
s
I
Vn
V
I
For constant
current
biasing:
TCV
3
g
T
E
VV
V
n
TT
T
k
T
I
b
V
d
Start with diode
IV
relation:
I
V
d
T
1
T
2
/
3
g
E
kT
s
IT
e
Note:
5
19
bandgap enegy
1.13eV (Si)
Boltzman constant
8.62 10 eV/ K
1.6 10
C
g
E
k
q
I
b
3
g
E
k
T
T
kT
V
q
290K
10mA
1pA
1
d
s
T
I
I
n
TCV
2mV/ C
21
2mV
VT
T
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Temperature Dependence
0
5
10
15
20
25
30
35
40
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Diode Voltage V, Volts
Current I, mA
Model at T=290K
Model at T=300K
Model at T=310K
Data at 300K
Note: for discrete diodes the ideality factor is closer to n=2
Significantly increased temperature coefficient
Ex: 1N4005 measured data
300K
10mA
5.5nA
1.82
d
s
T
I
I
n
TCV
5mV/ C
The change in voltage or current in diodes and transistors
must be dealt with in the design of circuits
Can be exploited too: a temperature sensor!
© Robert York, 20062007
Back to TOC
Temperature Dependence
I
d
V
d
T
1
T
2
V
b
21
6mA
I
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This note was uploaded on 03/17/2010 for the course ECE 2B taught by Professor York during the Winter '07 term at UCSB.
 Winter '07
 York

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