Page 70 - 30105-2003 การวิเคราะห์วงจรอิเล็กทรอนิกส์ความถี่สูง

62
2.

R R 2
1 B
B
R =
BB )
( R B 1 + R B 2
R BB i R BB (r bb′ + r b e ′ )
Z

$
Z = ( R BB Z i ) = = (2.7)
in
( R BB + Z i ) ( R BB + r bb′ + r b e ′ )
2.1.2.3 ก
)
#
*
Z (+# Z
o
out
"

2.1.2.3.1 Z - & 3

ก . ( +ก( ก !ก
o

*
- . ก (
& ก g V "
%
ก .

%
"
-
m b e ′
(,G
,% 2.7
Z = ∞ (2.8)
o
2.1.2.3.2 Z - & 3
"
ก . ( +ก( ก !ก
out
* "
%
% . ( +ก( ก !ก
,% 2.7

Z out = Z ( C R L )
R
o
R R
(
- ก Z = ∞ , R = C L ;
o out R + )
( C R L
R R (2.9)
C L

$
Z = R = R R ) =
out out ( C L R + )
( C R L

,
,
2.2 ก ,% 2.1 E
15 MHz , g m , r b e ′ , Z Z in , Z Z * %
o
i
out
g

T = 25 C
A
I C (dc ) I C (dc )
- .
ก ก (1.9) g = =
m
V (k T q )
T B
T = (273 25+ ) = 298 K
×
k T 1.38 10 − 23 × 298
V = B = = 25.7 mV
T
×
q 1.60 10 − 19
×
I C (dc ) 4.366 10 − 3
g m = = − = 169.883 mS
×
V T 25.7 10 3
β o 100
ก ก (1.10) r b e ′ = = − = 588.64 Ω
×
g m 169.883 10 3
3
×
R R 1 10 × 75 69.767 Ω
C L
R = = =
out
( R + R L ) ( 1 10 + 75 )
×
3
C
ก ก (2.6) Z = r + r
i bb′ b e ′
ก

ก
ก