Page 119 - 30105-2003 การวิเคราะห์วงจรอิเล็กทรอนิกส์ความถี่สูง

111
2.

3
×
×
R R 2 750 10 × 47 10 3 44.228 kΩ
1 G
G
* % R = = =
GG
×
×
( R G 1 + R G 2 ) ( 750 10 + 47 10 3 )
3
3
+
×
Ω
R FLCG = R + R GG = 75 44.228 10 = 44.303 k , C = 3.9 pF;
G
g
1
F = F ( L C G ) = 2 3.14 44.303 10 × 3.9 10 − 12 = 921.600 kHz
L
×
×
×
3
×
2I DSS  V GS 
ก ก (1.20) g =  1− 
m
V P  V P 
* % I DSS = 7.812 mA,V = − 4 V,V GS = − 1.108 V;
P
×
×
2 7.812 10 − 3  1− − 1.108 
g =
m − 4   − 4  
g = 3.906 10 − 3 × 0.723 2.824 mS
×
=
m
1
ก ก (2.58) F =
H
π
C
2 R FH T
3
×
×
R R 2 750 10 × 47 10 3
G
1 G
* % R = = = 44.228 kΩ
GG ) 3 3
×
×
( R G 1 + R G 2 ( 750 10 + 47 10 )
×
×
R R 75 44.228 10 3
g GG
R = ( R R ) = = = 74.873 Ω
FH g GG ) ( 3
( R + R GG 75 44.228 10 )
×
+
g
×
3
×
R R 2 10 × 1.5 10 3 857.142 Ω
D L
R out = = =
( R + R L ) ( 2 10 + 1.5 10 3 )
3
×
×
D
)
×
C = C iss + C g R = 5 10 − 12 + ( 1.2 10 − 12 × 2.824 10 − 3 × 857.142 = 7.904 pF
×
×
T
rss m out
F = 1 = 269.071 MHz
H
×
×
×
×
2 3.14 74.873 7.904 10 − 12
F 922 kHz F 269.071 MHz # (,5
% ! "
L H
2.2.5.8 ก

A V (F ) , A V (F ) (+# A V (F )
Mid L H
V o
ก ก (2.53) A = − = − g R
V (F Mid ) m out
E i
V o V o Z in Z in
ก ก (2.53a) A V (F ) = − = − × = − g Z ×
m out
Mid
E g E i ( R + Z in ) ( R + Z in )
g
g
V o
ก ก (2.57) A V (F ) = − = 0.707A V (F ) 45
L
E g Mid
V o
ก ก (2.58a) A V (F H ) = − E g = 0.707A V (F Mid ) − 45
ก

ก
ก