LTC1068 Series
Clock-Tunable, Quad
Second Order, Filter Building Blocks
FEATURES
s
s
DESCRIPTIO
s
s
s
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 50
µ
V
RMS
, LTC1068 50
µ
V
RMS
LTC1068-50 75
µ
V
RMS
, LTC1068-25 90
µ
V
RMS
Low Power Supply Current: 4.5mA, Single 5V,
LTC1068-50
Operation with
±5V
Power Supply, Single 5V
Supply or Single 3.3V Supply
APPLICATI
s
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
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
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
2
3
4
5
6
7
5V
0.1µF
8
9
10
11
R33 20k
R23 14k
R13 20k
V
IN2
12
13
14
INV B
HPB/NB
BPB
LPB
SB
LTC1068-25
NC
AGND
V
+
NC
SA
LPA
BPA
HPA/NA
INVA
V
INV C
HPC/NC
BPC
LPC
SC
–
28
27
26
25
24
23
22
21
20
19
18
17
16
15
R14 14k
1068 TA20a
R22 20k
R32 10k
10
V
OUT1
0
–10
– 5V
– 20
GAIN (dB)
1µF
f
CLK
= (25)(f – 3dB)
NC
CLK
NC
SD
LPD
BPD
HPD/ND
INVD
– 30
– 40
– 50
– 60
V
OUT2
R34 10k
R24 20k
– 70
– 80
0.1
1
RELATIVE FREQUENCY [f
IN
/(f – 3dB)]
10
U
Gain vs Frequency
1068 TA20b
UO
UO
1
LTC1068 Series
ABSOLUTE
AXI U
RATI GS
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
PACKAGE/ORDER I FOR ATIO
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
ORDER PART
NUMBER
TOP VIEW
SA 10
LPA 11
BPA 12
HPA/NA 13
INV A 14
LTC1068CG
LTC1068CG-200
LTC1068CG-50
LTC1068CG-25
LTC1068IG
LTC1068IG-200
LTC1068IG-50
LTC1068IG-25
G PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 110°C,
θ
JA
= 95°C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
Operating Supply Voltage Range
Voltage Swings
CONDITIONS
LTC1068 (Internal Op Amps) V
S
=
±5V,
T
A
= 25°V, unless otherwise noted.
MIN
3.14
q
q
q
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
Output Short-Circuit Current (Source/Sink)
DC Open-Loop Gain
GBW Product
Slew Rate
Analog Ground Voltage (Note 4)
2
U
U
W
W W
U
W
(Note 1)
Operating Temperature Range
LTC1068C................................................ 0°C to 70°C
LTC1068I ........................................... – 40°C to 85°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
INV B
HPB/NB
BPB
LPB
SB
AGND
V
+
SA
LPA
1
2
3
4
5
6
7
8
9
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
LTC1068CN
LTC1068IN
BPA 10
HPA/NA 11
INV A 12
N PACKAGE
24-LEAD PDIP
T
JMAX
= 110°C,
θ
JA
= 65°C/W
TYP
1.6
3.2
±4.1
17/6
20/15
85
6
10
2.5V
±2%
MAX
±5.5
UNITS
V
V
P-P
V
P-P
V
mA
mA
dB
MHz
V/µs
V
1.2
2.6
±3.4
LTC1068 Series
ELECTRICAL CHARACTERISTICS
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
q
q
q
q
q
q
q
LTC1068 (Complete Filter) V
S
=
±5V,
T
A
= 25°V, unless otherwise noted.
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
±15
±25
±40
mV
mV
mV
mV
RMS
MHz
8
11
15
mA
mA
mA
100
±0.3
q
q
q
q
q
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
LTC1068-200 (Internal Op Amps) V
S
=
±5V,
T
A
= 25°V, unless otherwise noted.
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
q
q
q
CONDITIONS
MIN
3.14
1.2
2.6
±3.4
TYP
1.6
3.2
±4.1
17/6
20/15
85
6
10
2.5V
±2%
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
q
MIN
TYP
200
±0.3
MAX
200
±0.8
200
±0.9
200
±0.8
200
±0.9
UNITS
%
%
%
%
200
±0.3
q
3
LTC1068 Series
ELECTRICAL CHARACTERISTICS
LTC1068-200 (Complete Filter) V
S
=
±5V,
T
A
= 25°V
,
unless otherwise noted.
PARAMETER
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
q
q
q
q
q
q
CONDITIONS
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
q
q
q
q
MIN
TYP
±0.25
±0.25
±1
±1
±1
±5
0
±2
±5
0.1
5.6
3.5
6.5
9.5
MAX
±0.9
±0.9
±3
±3
UNITS
%
%
%
%
ppm/°C
ppm/°C
±15
±25
±40
mV
mV
mV
mV
RMS
MHz
8
11
15
mA
mA
mA
LTC1068-50 (Internal Op Amps) V
S
=
±5V,
T
A
= 25°V, unless otherwise noted.
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
q
q
q
CONDITIONS
MIN
3.14
1.2
2.6
±3.4
TYP
1.8
3.6
±4.1
17/6
20/15
85
4
7
2.175V
±2%
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)
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
q
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
%
%
%
%
%
%
%
%
50
±0.3
q
q
q
q
q
±0.25
±0.25
±1
±1
4
LTC1068 Series
ELECTRICAL CHARACTERISTICS
LTC1068-50 (Complete Filter) V
S
=
±5V,
T
A
= 25°V
,
unless otherwise noted.
PARAMETER
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
q
q
q
q
q
q
CONDITIONS
MIN
TYP
±1
±5
0
–2
–5
0.16
3.4
3.0
4.3
6.0
MAX
UNITS
ppm/°C
ppm/°C
±15
±25
±40
mV
mV
mV
mV
RMS
MHz
5
8
11
mA
mA
mA
LTC1068-25 (Internal Op Amps) V
S
=
±5V,
T
A
= 25°V
,
unless otherwise noted.
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
q
q
q
CONDITIONS
MIN
3.14
1.2
2.6
±3.4
TYP
1.6
3.4
±4.1
17/6
20/15
85
6
10
2.5V
±2%
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)
LTC1068-25 (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
= 500kHz, Mode 1 (Note 3),
f
O
= 20kHz, Q = 5, V
IN
= 0.5V
RMS
,
R1 = R3 = 49.9k, R2 = 10k
V
S
=
±5V,
f
CLK
= 1MHz, Mode 1,
f
O
= 40kHz, 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
V
S
= 4.75V, f
CLK
= 500kHz, Q = 5 (Note 3)
V
S
=
±5V,
f
CLK
= 1MHz, Q = 5
V
S
= 4.75V, f
CLK
= 500kHz, Q = 5 (Note 3)
V
S
=
±5V,
f
CLK
= 1MHz, Q = 5
q
MIN
TYP
25
±0.3
MAX
25
±0.8
25
±0.9
25
±0.8
25
±0.9
±0.9
±0.9
±3
±3
UNITS
%
%
%
%
%
%
%
%
ppm/°C
ppm/°C
25
±0.3
q
q
q
q
q
±0.25
±0.25
±1
±1
±1
±5
5
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