LTC1068 Series
Clock-Tunable, Quad
Second Order, Filter Building Blocks
FEATURES
n
n
DESCRIPTION
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™ 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.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
FilterCAD is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
n
n
n
Four Identical 2nd Order Filter Sections in an
SSOP Package
2nd Order Section Center Frequency Error:
± 0.3% Typical and ±0.8% Maximum
Low Noise per 2nd Order Section, Q ≤ 5:
LTC1068-200 50µV
RMS
, LTC1068 50µV
RMS
LTC1068-50 75µV
RMS
, LTC1068-25 90µV
RMS
Low Power Supply Current: 4.5mA, Single 5V,
LTC1068-50
Operation with ± 5V Power Supply, Single 5V
Supply or Single 3.3V Supply
APPLICATIONS
n
n
Lowpass or Highpass Filters:
LTC1068-200, 0.5Hz to 25kHz; LTC1068, 1Hz to
50kHz; LTC1068-50, 2Hz to 50kHz; LTC1068-25,
4Hz to 200kHz
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
TYPICAL APPLICATION
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
V
IN1
R11 20k
R21 14k
R31 20k
1
2
3
4
5
6
7
5V
8
0.1µF
9
10
11
R33 20k
R23 14k
V
IN2
R13 20k
12
13
14
INV B
HPB/NB
BPB
LPB
SB
NC
LTC1068-25
INV C
HPC/NC
BPC
LPC
SC
V
–
NC
CLK
NC
SD
LPD
BPD
HPD/ND
INVD
28
27
26
25
24
23
22
21
20
19
18
17
16
15
R14 14k
1068 TA01
Gain vs Frequency
R22 20k
R32 10k
V
OUT1
GAIN (dB)
10
0
–10
–20
AGND
V
+
NC
SA
LPA
BPA
HPA/NA
INVA
1µF
–5V
–30
–40
–50
–60
–70
f
CLK
= (25)(f – 3dB)
R34 10k
R24 20k
V
OUT2
–80
0.1
1
RELATIVE FREQUENCY [f
IN
/(f – 3dB)]
10
1068 TA02
1068fc
1
LTC1068 Series
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Total Supply Voltage (V
+
to V
–
) ................................12V
Power Dissipation .............................................. 500mW
Input Voltage at Any Pin......V
–
– 0.3V ≤ V
IN
≤ V
+
+ 0.3V
Storage Temperature Range................... –65°C to 150°C
Operating Temperature Range
LTC1068C ................................................ 0°C to 70°C
LTC1068I............................................. –40°C to 85°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
TOP VIEW
INV B
HPB/NB
BPB
LPB
SB
NC
AGND
V
+
NC
1
2
3
4
5
6
7
8
9
28 INV C
27 HPC/NC
26 BPC
25 LPC
24 SC
23 V
–
22 NC
21 CLK
20 NC
19 SD
18 LPD
17 BPD
16 HPD/ND
15 INV D
INV B
HPB/NB
BPB
LPB
SB
AGND
V
+
SA
LPA
1
2
3
4
5
6
7
8
9
TOP VIEW
24 INV C
23 HPC/NC
22 BPC
21 LPC
20 SC
19 V
–
18 CLK
17 SD
16 LPD
15 BPD
14 HPD/ND
13 INV D
N PACKAGE
24-LEAD PDIP
SA 10
LPA 11
BPA 12
HPA/NA 13
INV A 14
BPA 10
HPA/NA 11
INV A 12
G PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 110°C,
θ
JA
= 65°C/W
T
JMAX
= 110°C,
θ
JA
= 95°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC1068CG#PBF
LTC1068IG#PBF
LTC1068-200CG#PBF
LTC1068-200IG#PBF
LTC1068-50CG#PBF
LTC1068-50IG#PBF
LTC1068-25CG#PBF
LTC1068-25IG#PBF
LTC1068CN#PBF
LTC1068IN#PBF
TAPE AND REEL
LTC1068CG#TRPBF
LTC1068IG#TRPBF
LTC1068-200CG#TRPBF
LTC1068-200IG#TRPBF
LTC1068-50CG#TRPBF
LTC1068-50IG#TRPBF
LTC1068-25CG#TRPBF
LTC1068-25IG#TRPBF
NA
NA
PART MARKING
LTC1068
LTC1068
LTC1068
LTC1068
LTC1068
LTC1068
LTC1068
LTC1068
LTC1068
LTC1068
PACKAGE DESCRIPTION
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
24-Lead PDIP
24-Lead PDIP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
1068fc
2
LTC1068 Series
ELECTRICAL CHARACTERISTICS
PARAMETER
Operating Supply Voltage Range
Voltage Swings
V
S
= 3.14V, R
L
= 5k (Note 2)
V
S
= 4.75V, R
L
= 5k (Note 3)
V
S
= ±5V, R
L
= 5k
V
S
= ± 4.75V
V
S
= ±5V
R
L
= 5k
V
S
= ±5V
V
S
= ±5V
V
S
= 5V, Voltage at AGND
l
l
l
LTC1068 (Internal Op Amps). The
l
denotes the specifications which apply
over the full operating temperature range, otherwise specifications are at V
S
= ± 5V, T
A
= 25°V, unless otherwise noted.
CONDITIONS
MIN
3.14
1.2
2.6
±3.4
1.6
3.2
±4.1
17/6
20/15
85
6
10
2.5V ±2%
TYP
MAX
± 5.5
UNITS
V
V
P-P
V
P-P
V
mA
mA
dB
MHz
V/µs
V
Output Short-Circuit Current (Source/Sink)
DC Open-Loop Gain
GBW Product
Slew Rate
Analog Ground Voltage (Note 4)
LTC1068 (Complete Filter) V
S
= ± 5V, T
A
= 25°V, unless otherwise noted.
PARAMETER
Clock-to-Center Frequency Ratio (Note 5)
CONDITIONS
V
S
= 4.75V, f
CLK
= 1MHz, Mode 1 (Note 3),
f
O
= 10kHz, Q = 5, V
IN
= 0.5V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
V
S
= ± 5V, f
CLK
= 1MHz, Mode 1,
f
O
= 10kHz, Q = 5, V
IN
= 1V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
Clock-to-Center Frequency Ratio,
Side-to-Side Matching (Note 5)
Q Accuracy (Note 5)
f
O
Temperature Coefficient
Q Temperature Coefficient
DC Offset Voltage (Note 5)
(See Table 1)
V
S
= ±5V, f
CLK
= 1MHz, V
OS1
(DC Offset of Input Inverter)
V
S
= ± 5V, f
CLK
= 1MHz, V
OS2
(DC Offset of First Integrator)
V
S
= ±5V, f
CLK
= 1MHz, V
OS3
(DC Offset of Second Integrator)
Clock Feedthrough
Max Clock Frequency (Note 6)
Power Supply Current
V
S
= ± 5V, f
CLK
= 1MHz
V
S
= ±5V, Q ≤ 2.0, Mode 1
V
S
= 3.14V, f
CLK
= 1MHz (Note 2)
V
S
= 4.75V, f
CLK
= 1MHz (Note 3)
V
S
= ±5V, f
CLK
= 1MHz
l
l
l
l
l
l
l
MIN
TYP
100 ± 0.3
MAX
100 ±0.8
100 ±0.9
100 ±0.8
100 ±0.9
±0.9
±0.9
±3
±3
UNITS
%
%
%
%
%
%
%
%
ppm/°C
ppm/°C
100 ± 0.3
l
l
l
l
l
V
S
= 4.75V, f
CLK
= 1MHz, Q = 5 (Note 3)
V
S
= ±5V, f
CLK
= 1MHz, Q = 5
V
S
= 4.75V, f
CLK
= 1MHz, Q = 5 (Note 3)
V
S
= ±5V, f
CLK
= 1MHz, Q = 5
±0.25
±0.25
±1
±1
±1
±5
0
±2
±5
0.1
5.6
3.5
6.5
9.5
±15
±25
±40
mV
mV
mV
mV
RMS
MHz
8
11
15
mA
mA
mA
1068fc
3
LTC1068 Series
ELECTRICAL CHARACTERISTICS
PARAMETER
Operating Supply Voltage Range
Voltage Swings
V
S
= 3.14V, R
L
= 5k (Note 2)
V
S
= 4.75V, R
L
= 5k (Note 3)
V
S
= ±5V, R
L
= 5k
V
S
= ± 4.75V
V
S
= ±5V
R
L
= 5k
V
S
= ±5V
V
S
= ±5V
V
S
= 5V, Voltage at AGND
l
l
l
LTC1068-200 (Internal Op Amps). The
l
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at V
S
= ± 5V, T
A
= 25°V, unless otherwise noted.
CONDITIONS
MIN
3.14
1.2
2.6
±3.4
1.6
3.2
±4.1
17/6
20/15
85
6
10
2.5V ±2%
TYP
MAX
±5.5
UNITS
V
V
P-P
V
P-P
V
mA
mA
dB
MHz
V/µs
V
Output Short-Circuit Current (Source/Sink)
DC Open-Loop Gain
GBW Product
Slew Rate
Analog Ground Voltage (Note 4)
LTC1068-200 (Complete Filter) V
S
= ±5V, T
A
= 25°V, unless otherwise noted.
PARAMETER
Clock-to-Center Frequency Ratio (Note 5)
CONDITIONS
V
S
= 4.75V, f
CLK
= 1MHz, Mode 1 (Note 3),
f
O
= 5kHz, Q = 5, V
IN
= 0.5V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
V
S
= ± 5V, f
CLK
= 1MHz, Mode 1,
f
O
= 5Hz, Q = 5, V
IN
= 1V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
Clock-to-Center Frequency Ratio,
Side-to-Side Matching (Note 5)
Q Accuracy (Note 5)
f
O
Temperature Coefficient
Q Temperature Coefficient
DC Offset Voltage (Note 5)
(See Table 1)
V
S
= ±5V, f
CLK
= 1MHz, V
OS1
(DC Offset of Input Inverter)
V
S
= ± 5V, f
CLK
= 1MHz, V
OS2
(DC Offset of First Integrator)
V
S
= ±5V, f
CLK
= 1MHz, V
OS3
(DC Offset of Second Integrator)
Clock Feedthrough
Max Clock Frequency (Note 6)
Power Supply Current
V
S
= ± 5V, f
CLK
= 1MHz
V
S
= ±5V, Q ≤ 2.0, Mode 1
V
S
= 3.14V, f
CLK
= 1MHz (Note 2)
V
S
= 4.75V, f
CLK
= 1MHz (Note 3)
V
S
= ±5V, f
CLK
= 1MHz
l
l
l
l
l
l
l
MIN
TYP
200 ±0.3
MAX
200 ±0.8
200 ±0.9
200 ±0.8
200 ±0.9
±0.9
±0.9
±3
±3
UNITS
%
%
%
%
%
%
%
%
ppm/°C
ppm/°C
200 ±0.3
l
l
l
l
l
V
S
= 4.75V, f
CLK
= 1MHz, Q = 5 (Note 3)
V
S
= ±5V, f
CLK
= 1MHz, Q = 5
V
S
= 4.75V, f
CLK
= 1MHz, Q = 5 (Note 3)
V
S
= ±5V, f
CLK
= 1MHz, Q = 5
± 0.25
± 0.25
±1
±1
±1
±5
0
±2
±5
0.1
5.6
3.5
6.5
9.5
±15
±25
±40
mV
mV
mV
mV
RMS
MHz
8
11
15
mA
mA
mA
1068fc
4
LTC1068 Series
ELECTRICAL CHARACTERISTICS
PARAMETER
Operating Supply Voltage Range
Voltage Swings
V
S
= 3.14V, R
L
= 5k (Note 2)
V
S
= 4.75V, R
L
= 5k (Note 3)
V
S
= ±5V, R
L
= 5k
V
S
= ± 3.14V
V
S
= ±5V
R
L
= 5k
V
S
= ±5V
V
S
= ±5V
V
S
= 5V, Voltage at AGND
l
l
l
LTC1068-50 (Internal Op Amps). The
l
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at V
S
= ± 5V, T
A
= 25°V, unless otherwise noted.
CONDITIONS
MIN
3.14
1.2
2.6
±3.4
1.8
3.6
±4.1
17/6
20/15
85
4
7
2.175V ±2%
TYP
MAX
± 5.5
UNITS
V
V
P-P
V
P-P
V
mA
mA
dB
MHz
V/µs
V
Output Short-Circuit Current (Source/Sink)
DC Open-Loop Gain
GBW Product
Slew Rate
Analog Ground Voltage (Note 4)
LTC1068-50 (Complete Filter) V
S
= ±5V, T
A
= 25°V, unless otherwise noted.
PARAMETER
Clock-to-Center Frequency Ratio (Note 5)
CONDITIONS
V
S
= 3.14V, f
CLK
= 250kHz, Mode 1 (Note 2),
f
O
= 5kHz, Q = 5, V
IN
= 0.34V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
V
S
= ± 5V, f
CLK
= 500kHz, Mode 1,
f
O
= 10kHz, Q = 5, V
IN
= 1V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
Clock-to-Center Frequency Ratio,
Side-to-Side Matching (Note 5)
Q Accuracy (Note 5)
f
O
Temperature Coefficient
Q Temperature Coefficient
DC Offset Voltage (Note 5)
(See Table 1)
V
S
= ±5V, f
CLK
= 500kHz, V
OS1
(DC Offset of Input Inverter)
V
S
= ± 5V, f
CLK
= 500kHz, V
OS2
(DC Offset of First Integrator)
V
S
= ±5V, f
CLK
= 500kHz, V
OS3
(DC Offset of Second Integrator)
Clock Feedthrough
Max Clock Frequency (Note 6)
Power Supply Current
V
S
= ± 5V, f
CLK
= 500kHz
V
S
= ±5V, Q ≤ 1.6, Mode 1
V
S
= 3.14V, f
CLK
= 250kHz (Note 2)
V
S
= 4.75V, f
CLK
= 250kHz (Note 3)
V
S
= ±5V, f
CLK
= 500kHz
l
l
l
l
l
l
l
MIN
TYP
50 ± 0.3
MAX
50 ±0.8
50 ±0.9
50 ±0.8
50 ±0.9
±0.9
±0.9
±3
±3
UNITS
%
%
%
%
%
%
%
%
ppm/°C
ppm/°C
50 ± 0.3
l
l
l
l
l
V
S
= 3.14V, f
CLK
= 250kHz, Q = 5 (Note 2)
V
S
= ±5V, f
CLK
= 500kHz, Q = 5
V
S
= 3.14V, f
CLK
= 250kHz, Q = 5 (Note 2)
V
S
= ±5V, f
CLK
= 500kHz, Q = 5
± 0.25
± 0.25
±1
±1
±1
±5
0
–2
–5
0.16
3.4
3.0
4.3
6.0
±15
±25
±40
mV
mV
mV
mV
RMS
MHz
5
8
11
mA
mA
mA
1068fc
5
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