ltc1060csw-trpbf Linear Technology Corporation, ltc1060csw-trpbf Datasheet - Page 17

• Manufacturer Part Number: ltc1060csw-trpbf
• Description: Universal Dual Filter Building Block
• Manufacturer: Linear Technology Corporation

COMM
mode 2b section (Figure 22), has a gain exceeding unity
which limits the dynamic range of the overall filter. For
very selective bandpass/bandreject filters, the mode 3a
W W
E TS
U
Figure 20. Combining Mode 3 with Mode 3a to Make The 4th Order BP Filter of Figure 21 with Improved
Dynamics. The Gain at Each Output Node is ≤ 0dB for all Input Frequencies.
Figure 21. The BP Filter of Figure 20, When Swept From a 2kHz to 20kHz Center Frequency.
–20dB
–30dB
–40dB
–50dB
–10dB
0dB
1.5kHz
ON
V
NOTE: FOR CLOCK FREQUENCIES ABOVE 700kHz, A 12pF CAPACITOR ACROSS R41 AND A 20pF
IN
U
1.75kHz
R11
THE
R11 = 155.93k
R
R42 = 5k
CAPACITOR ACROSS R42 WERE USED TO PREVENT THE PASSBAND RIPPLE FROM ANY
ADDITIONAL PEAKING
H1
T
2
L OR CMOS
= 13.2k
CLOCK IN
V + = 7.5V
R41
R31
R21
2kHz
M
W
–7.5V
ODES OF OPERATIO
2.25kHz
R21 = 5k
R
R
L1
L2
PRECISE RESISTOR VALUES
10
1
2
3
4
5
6
7
8
9
f
= 10.74k
= 6.11k
CLK
LP
BP
HP
INV
S1A
S
V
V
LSh
CLK
= 100kHz
A/B
A
D
+
A
A
+
A
A
2.5kHz
LTC1060
A
50/100
R31 = 152k
R22 = 5.26k
R
AGND
R
R
H2
CLK
INV
H1
L1
BP
HP
S1B
LP
V
V
A
D
= 5k
B
B
B
B
B
–
–
20
19
18
17
16
15
14
13
12
11
–10dB
–20dB
–30dB
–40dB
–50dB
0dB
approach, as in Figure 20, yields better dynamic range
since the external op amp helps to optimize the dynamics
of the output nodes of the LTC1060.
7.5V
15kHz
R42
R32
R22
–7.5V
R41 = 5.27k
R32 = 151.8k
R
G
= 37.3k
17.5kHz
R
R
L2
H2
U
20kHz
–
EXTERNAL
+
OP AMP
R
22.5kHz
G
f
CLK
LTC1060 • CM02
TLC1060 • CMO03
= 1MHz
25kHz
V
OUT
LTC1060
17
1060fb