EL5153 INTERSIL [Intersil Corporation], EL5153 Datasheet - Page 11

• Manufacturer Part Number: EL5153
• Description: 270MHz Ultra-Accurate Amplifiers
• Manufacturer: INTERSIL [Intersil Corporation]

Application Circuits
Sullen Key Low Pass Filter
A common and easy to implement filter taking advantage of
the wide bandwidth, low offset and low power demands of
the EL5152. A derivation of the transfer function is provided
for convenience. (See Figure 28.)
V1
R1
1K
R2
1K
C2
1n
RA
11
1K
C1
1n
RB
1K
3
2
EL5152, EL5153, EL5252, EL5455
U1A
V3
+
-
V2
FIGURE 28. SULLEN KEY LOW PASS FILTER
11
V+
V-
L1
10µH
4
L3
10µH
C6
C5
5V
5V
1n
1n
R5
1K
R6
1K
1
C3
C4
1n
1n
R7
V
OUT
1K
Sullen Key High Pass Filter
Again this useful filter benefits from the characteristics of the
EL5152. The transfer function is very similar to the low pass
so only the results are presented. (See Figure 29.)
K
( H
( H
Holp
Holp
Vo
wo
Q
wo
Q
V
1
=
) s
R
jw
=
=
−
=
=
=
1
1
1 (
3
=
)
Vi
+
K
=
=
RC
=
−
−
1
R
1
K
K
R
R
R
1
R
K
1
K
1
B
A
+
1
2
C
−
C
)
C
1
K
1
1
R
w
1
2
R
R
Vo
R
R
s
−
2
2
2
2
C
1
2
R
+
V
C
C
C
2
1
1
1
2
1
C
2
Equations simplify if we let all
components be equal R=C
s
V
+
2
1
+
R
1
+
Vo
2
1
((
C
C
R
R
1
1
−
1
2
1
2
s
−
C
+
C
Vi
2
K
1
jw
R )
=
+
((
K
0
1
1
C
1
R
−
R
1
2
K
+
1
C
C
R )
R
1
2
1
1
C
C
2
1
+
+
R
R
21
1
October 3, 2005
C
C
2
2
+
s )
FN7385.4
R
+
2
C
1
2
)