ISL55004_14 Datasheet, PDF (10/12 Pages) Intersil Corporation – High Supply Voltage 200MHz Unity-Gain Stable Operational Amplifier

ISL55004
R₁
V₁
1kΩ
C₁
1nF
R₂
1kΩ C₂
1nF
R_A
1kΩ
V₂
5V
C₅
1nF
+ ^V+
- _V-
R_B
1kΩ
C₅
1nF
V₃
5V
V_OUT
R₇
1kΩ
FIGURE 28. SALLEN KEY LOW PASS FILTER
K = 1+ ^RB
RA
Vo = K ¹ V1
R2C2s + 1
Vo
V1− Vi _{1+ K − V1 +} Vo − Vi _{= 0}
R1
R2
1
C1s
H(s) =
K
R1C1R2C2s² + ((1− K)R1C1+ R1C2 + R21C2)s + 1
H(jw) =
1
1− w ²R1C1R2C2 + jw((1− K)R1C1+ R1C2 + R2C2)
Holp = K
wo =
1
R1C1R2C2
Q=
1
(1− K) ^R1C1 + ^R1C2 +
R2C2 R2C1
R2C2
R1C1
Holp = K
wo = ¹
RC
Q= ¹
3−K
Equations simplify if we let all
components be equal R=C
R₁
V₁
1kΩ
C₁
1nF
R₂
1kΩ C₂
1nF
R_A
1kΩ
V₂
5V
C₅
1nF
+ ^V+
- _V-
R_B
1kΩ
C₅
1nF
V₃
5V
V_OUT
R₇
1kΩ
Holp = K
wo =
1
R1C1R2C2
Q=
1
(1− K) ^R1C1 + ^R1C2 +
R2C2 R2C1
R2C2
R1C1
Holp = ^K
4−K
wo = ²
RC
Equations simplify if we let
all components be equal R=C
Q= ²
4−K
FIGURE 29. SALLEN KEY HIGH PASS FILTER
10
FN6219.2
July 27, 2006