LTC1068 Datasheet, PDF (1/28 Pages) Linear Technology – Clock-Tunable, Quad Second Order, Filter Building Blocks

LTC1068 Series
Clock-Tunable, Quad
Second Order, Filter Building Blocks
FEATURES
s _{Four Identical 2nd Order Filter Sections in an}
SSOP Package
s _{2nd Order Section Center Frequency Error:}
±0.3% Typical and ±0.8% Maximum
s _{Low Noise per 2nd Order Section, Q ≤ 5:}
LTC1068-200 50µV_RMS, LTC1068 50µV_RMS
LTC1068-50 75µV_RMS, LTC1068-25 90µV_RMS
s _{Low Power Supply Current: 4.5mA, Single 5V,}
LTC1068-50
s _{Operation with ±5V Power Supply, Single 5V}
Supply or Single 3.3V Supply
APPLICATI S
s _{Lowpass or Highpass Filters:}
LTC1068-200, 0.5Hz to 25kHz; LTC1068, 1Hz to
50kHz; LTC1068-50, 2Hz to 50kHz; LTC1068-25,
4Hz to 200kHz
s _{Bandpass or Bandreject (Notch) Filters:}
LTC1068-200, 0.5Hz to 15kHz; LTC1068, 1Hz to
30kHz; LTC1068-50, 2Hz to 30kHz; LTC1068-25,
4Hz to 140kHz
DESCRIPTIO
The LTC^®1068 product family consists of four monolithic
clock-tunable filter building blocks. Each product contains
four matched, low noise, high accuracy 2nd order switched-
capacitor filter sections. An external clock tunes the center
frequency of each 2nd order filter section. The LTC1068
products differ only in their clock-to-center frequency
ratio. The clock-to-center frequency ratio is set to 200:1
(LTC1068-200), 100:1 (LTC1068), 50:1 (LTC1068-50) or
25:1 (LTC1068-25). External resistors can modify the
clock-to-center frequency ratio. High performance, quad
2nd order, dual 4th order or 8th order filters can be
designed with an LTC1068 family product. Designing
filters with an LTC1068 product is fully supported by
FilterCAD^TM filter design software for Windows^®.
The LTC1068 products are available in a 28-pin SSOP
surface mount package. A customized version of an
LTC1068 family product can be obtained in a 16-lead SO
package with internal thin-film resistors. Please contact
LTC Marketing for details.
, LTC and LT are registered trademarks of Linear Technology Corporation.
FilterCAD is a trademark of Linear Technology Corporation.
Windows is a registered trademark of Microsoft Corporation.
TYPICAL APPLICATI
Dual, Matched, 4th Order Butterworth Lowpass Filters, Clock-Tunable
Up to 200kHz f – 3dB = f_CLK/25, 4th Order Filter Noise = 60µV_RMS
R12 14k
R11 20k
V_IN1
R21 14k
R31 20k
1
INV B
2
HPB/NB
3
BPB
28
INV C
27
HPC/NC
26
BPC
4
LPB
25
LPC
5
SB
24
SC
6
LTC1068-25
NC
V^–
23
7
AGND
22
NC
5V
8 _V+
21
CLK
0.1µF
9
NC
20
NC
10
SA
19
SD
R13 20k
V_IN2
R33 20k
R23 14k
11
LPA
12
BPA
13
HPA/NA
14
INVA
18
LPD
17
BPD
16
HPD/ND
15
INVD
R22 20k
R32 10k
1µF
R34 10k
R24 20k
R14 14k
1068 TA20a
V_OUT1
– 5V
f_CLK = (25)(f – 3dB)
V_OUT2
Gain vs Frequency
10
0
–10
– 20
– 30
– 40
– 50
– 60
– 70
– 80
0.1
1
10
RELATIVE FREQUENCY [f_IN/(f – 3dB)]
1068 TA20b
1