W
U
ODES OF OPERATIO
LTC1264
R1
VIN
R4
R3
R2
–
+
AGND
CC
HP
S
BP
+
–
Σ
∫
∫
RH
1/4 LTC1264
√ fi
=
fCLK
20
;
fn
=
fi
1 + RH
RL
√ fO = fi
1 + R2
R4
LP
( )( ) ( ) HOLPn (f = 0)=
RG
RH
+
RG
RL
R2
R1
1
1
+
R2
R4
RG
( ) √ ( ) Q
=
1.005
R3
R2
1 + R2
R4
1
1–
R3
6.42•R4
RL
–
+
LOWPASS
NOTCH
OUTPUT
EXTERNAL OP AMP OR
INPUT OP AMP OF THE
LTC1264, SIDES A, B, C, D
1264 G09
Figure 9. Mode 2n, 2nd Order Filter Providing a Lowpass Notch Output
BLOCK DIAGRA
INV A 12
–
AGND 6
+
INV B 1
–
+
INV C 24
–
+
INV D 13
–
+
HPA/NA
11
+Σ
–
HPB/NB
8
2
SA
+Σ
–
5
HPC/NC SB
23
+Σ
–
20
HPD/ND SC
14
+Σ
–
17
SD
BPA
LPA
10
9
+∫
+∫
7 V+
18 CLK
19 V –
BPB
LPB
3
4
+∫
+∫
BPC
LPC
22
21
+∫
+∫
BPD
LPD
15
16
+∫
+∫
1264 BD
1264fb
9