RC4156N Просмотр технического описания (PDF) - Fairchild Semiconductor
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RC4156N Datasheet PDF : 13 Pages
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RC4156/RC4157
PRODUCT SPECIFICATION
VIN R3
Trim
Gain
and Q
R7
R5
100K
Set Center Frequency
R4
10K
2
1
3
C1
6 1000 pF
9
R1
5
7
R2
10
RC4156/57
A
R6
100K
RC4156/57
B
VBP
Figure 16. Bandpass Active Filter
C2
1000 pF
8
RC4156/57
C
65-0752
These equations can be combined to obtain the transfer function:
VBP(s)
=
–
--------1----------
R1C1S
VH
P(
s
)
and
VLP(s)
=
–--------1----------
R2C2S
VB
P
(
s
)
-VV----BI--N--P--(-(--ss--)-)
=
R-----4- ⋅ -------1-------S
-------------------------------------------------------------R----3--------R----1----C----1-----------------------------------------------------------------
S2
+
-------R-----7--------
R6 + R7
1
+
R-----4-
R5
+
RR-----43-
R-----1--1-C-----1-
S
+
RR-----45-
R-----1---C-----1-1--R----2----C----2-
Defining 1/R1C1 as ω1, 1/R2C2 as ω2, and substituting in
the assigned values for R4, R5, and R6, then the transfer
function simplifies to:
-VV----BI--N--P--(-(--ss--)-)
=
-------------------------1-R------0---3---4----⋅---ω----1---s-------------------------
1.1 + -1---0---4
S2 +
---------------R----3---
1 + 1----0---5
ω1s + ω-----1-1--ω----2-
R7
This is now in a convenient form to look at the center-
frequency ω0 and filter Q.
ω0 = 0.1ω1ω2
ω0 = 10–9 0.1R1R2 and
1 + 1----0---5
Q=
-------------R----7-----
1.1 + 1----0---4
ω0
R3
The frequency responses for various values of Q are shown
in Figure 17.
0
-10
-20
-30
-40
-50
-60
0.1
VBP =
V IN
Q = 0.5
Q = 1.0
Q = 2.0
Q = 5.0
Q = 10
Q = 20
Q = 50
Q = 100
1.0
10
ω
ωo
ω1
ωo Q
1-
ω2
ωo
2+
1 ω2
Q ωo
Figure 17. Bandpass Transfer Characteristics Normalized
for Unity Gain and Frequency
REV. 1.0.1 6/13/01
9
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