LTC1066-1
14-Bit DC Accurate
Clock-Tunable, 8th Order Elliptic
or Linear Phase Lowpass Filter
FEATURES
■
■
■
■
■
■
■
■
■
■
■
DESCRIPTIO
DC Gain Linearity: 14 Bits
Maximum DC Offset:
±1.5mV
DC Offset TempCo: 7µV/°C
Device Fully Tested at f
CUTOFF
= 80kHz
Maximum Cutoff Frequency: 120kHz (V
S
=
±8V)
Drives 1kΩ Load with 0.02% THD or Better
Signal-to-Noise Ratio: 90dB
Input Impedance: 500MΩ
Selectable Elliptic or Linear Phase Response
Operates from Single 5V up to
±8V
Power Supplies
Available in an 18-Pin SO Wide Package
The LTC
®
1066-1 is an 8th order elliptic lowpass filter
which simultaneously provides clock-tunability and DC
accuracy. The unique and proprietary architecture of the
filter allows 14 bits of DC gain linearity and a maximum of
1.5mV DC offset. An external RC is required for DC
accurate operation. With
±7.5V
supplies, a 20k resistor
and a 1µF capacitor, the cutoff frequency can be tuned
from 800Hz to 100kHz. A clock-tunable 10Hz to 100kHz
operation can also be achieved (see Typical Application
section).
The filter does not require any external active components
such as input/output buffers. The input/output impedance
is 500MΩ/0.1Ω and the output of the filter can source or
sink 40mA. When pin 8 is connected to V
+
, the clock-to-
cutoff frequency ratio is 50:1 and the input signal is
sampled twice per clock cycle to lower the risk of aliasing.
For frequencies up to 0.75f
CUTOFF
, the passband ripple is
±0.15dB.
The gain at f
CUTOFF
is –1dB and the filter’s
stopband attenuation is 80dB at 2.3f
CUTOFF
. Linear phase
operation is also available with a clock-to-cutoff frequency
ratio of 100:1 when pin 8 is connected to ground.
The LTC1066-1 is available in an 18-pin SO Wide package.
APPLICATIO S
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Instrumentation
Data Acquisition Systems
Anti-Aliasing Filters
Smoothing Filters
Audio Signal Processing
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
Clock-Tunable, DC Accurate, 800Hz to 80kHz Elliptic Lowpass Filter
20k
1µF
1
2
V
IN
–7.5V
SHORT CONNECTION UNDER
IC AND SHIELDED BY A
GROUND PLANE
BYPASS THE POWER SUPPLIES
WITH 0.1µF DISC CERAMIC
40kHz
≤
f
CLK
≤
4MHz
7.5V
3
4
5
6
7
8
9
18
V
+
OUT A
17
–IN A
OUT B
16
+IN A
+IN B
15
V
–
LTC1066-1 GND
14
FILTER
IN
V
+
13
CONNECT 1
COMP 2
12
FILTER
OUT
CONNECT 2
11
COMP 1
50/100
10
V
–
CLK
7.5V
V
OUT
;
V
OS(OUT)
=
2.5mV
MAX
10
0
–10
–20
GAIN (dB)
30k
15pF
–7.5V
1066-1 TA01
U
Amplitude Response
f
C
= 80kHz
–30
–40
–50
–60
–70
–80
–90
100
1k
10k
100k
FREQUENCY (Hz)
1M
1066-1 TA02
U
U
f
C
= 800Hz
10661fa
1
LTC1066-1
ABSOLUTE
(Note 1)
AXI U RATI GS
V
–
)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
OUT A 1
–IN A 2
+IN A 3
V
–
V
+
4
5
18 V
+
17 OUT B
16 +IN B
15 GND
14 FILTER
IN
13 COMP 2
12 CONNECT 2
11 COMP 1
10 V
–
.......................... 16.5V
Power Dissipation ............................................. 700mW
Burn-In Voltage ................................................... 16.5V
Voltage at Any Input ..... (V
–
– 0.3V)
≤
V
IN
≤
(V
+
+ 0.3V)
Maximum Clock Frequency
V
S
=
±8V
....................................................... 6.1MHz
V
S
=
±7.5V
.................................................... 5.4MHz
V
S
=
±5V
....................................................... 4.1MHz
V
S
= Single 5V ............................................... 1.8MHz
Operating Temperature Range* .................. 0°C to 70°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
* For an extended operating temperature range contact LTC Marketing
for details.
Total Supply Voltage (V
+
to
ORDER PART
NUMBER
LTC1066-1CSW
CONNECT 1 6
FILTER
OUT
7
50/100 8
CLK 9
SW PACKAGE
18-LEAD PLASTIC SO WIDE
T
JMAX
= 110°C,
θ
JA
= 75°C/W
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
(See Test Circuit)
The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at V
S
=
±7.5V,
R
L
= 1k, T
A
= 25°C, f
CLK
signal level is TTL or CMOS (maximum clock rise or fall time
≤
1µs) unless otherwise specified. All AC gain
measurements are referenced to passband gain.
PARAMETER
Passband Gain (0.01f
CUTOFF
to 0.25f
CUTOFF
)
Passband Ripple (0.01f
CUTOFF
to 0.75f
CUTOFF
)
for f
CLK
/f
CUTOFF
= 50:1
Gain at 0.50f
CUTOFF
for f
CLK
/f
CUTOFF
= 50:1
CONDITIONS
f
CLK
= 400kHz, f
TEST
= 2kHz
f
CUTOFF
≤
50kHz (See Note on Test Circuit)
f
CLK
= 400kHz, f
TEST
= 4kHz
●
●
ELECTRICAL CHARACTERISTICS
MIN
– 0.18
TYP
0.16
±0.15
MAX
0.36
UNITS
dB
dB
– 0.09
– 0.14
– 0.16
– 0.22
– 0.18
– 0.22
– 0.36
– 0.45
– 0.65
– 0.85
– 1.50
– 1.80
– 2.10
– 2.30
– 2.20
– 2.50
– 56
– 54
– 53
– 51
– 50
– 48
0.02
0.05
– 0.05
– 0.10
– 0.05
– 0.10
– 0.20
– 0.30
– 0.30
– 0.40
– 1.10
– 1.20
– 1.60
– 1.60
– 1.60
– 1.60
– 58
– 57
– 56
– 55
– 52
– 51
0.09
0.14
0.02
0.02
0.05
0.05
0.05
0.05
0.25
0.75
– 0.05
– 0.05
– 1.20
– 1.20
– 0.05
0.25
– 64
– 64
– 62
– 62
– 60
– 60
f
CLK
= 2MHz, f
TEST
= 20kHz
●
Gain at 0.75f
CUTOFF
for f
CLK
/f
CUTOFF
= 50:1
f
CLK
= 400kHz, f
TEST
= 6kHz
●
f
CLK
= 2MHz, f
TEST
= 30kHz
●
f
CLK
= 4MHz, f
TEST
= 60kHz
●
Gain at 1.00f
CUTOFF
for f
CLK
/f
CUTOFF
= 50:1
f
CLK
= 400kHz, f
TEST
= 8kHz
●
f
CLK
= 2MHz, f
TEST
= 40kHz
●
f
CLK
= 4MHz, f
TEST
= 80kHz
●
Gain at 2.00f
CUTOFF
for f
CLK
/f
CUTOFF
= 50:1
f
CLK
= 400kHz, f
TEST
= 16kHz
●
f
CLK
= 2MHz, f
TEST
= 80kHz
●
f
CLK
= 4MHz, f
TEST
= 160kHz
●
10661fa
2
U
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
W
U
U
W W
W
LTC1066-1
(See Test Circuit)
The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at V
S
=
±7.5V,
R
L
= 1k, T
A
= 25°C, f
CLK
signal level is TTL or CMOS (maximum clock rise or fall time
≤
1µs) unless otherwise specified. All AC gain
measurements are referenced to passband gain.
PARAMETER
Gain at f
CUTOFF
for f
CLK
= 20kHz, V
S
=
±7.5V
Gain at f
CUTOFF
for V
S
=
±2.375V,
f
CLK
/f
CUTOFF
= 50:1
Gain at 70kHz for V
S
=
±5V,
f
CLK
/f
CUTOFF
= 50:1
Linear Phase Response
f
CLK
/f
CUTOFF
= 100:1,
Pin 8 at GND
Phase at 0.25f
CUTOFF
Gain at 0.25f
CUTOFF
Phase at 0.50f
CUTOFF
Gain at 0.50f
CUTOFF
Phase at 0.75f
CUTOFF
Gain at 0.75f
CUTOFF
Phase at f
CUTOFF
Gain at f
CUTOFF
Input Bias Current
Input Offset Current
Input Offset Current TempCo
Output Voltage Offset TempCo
Output Offset Voltage
CONDITIONS
f
CLK
/f
CUTOFF
= 50:1, f
TEST
= 400Hz
f
CLK
= 1MHz, f
TEST
= 20kHz
f
CLK
= 4MHz, f
TEST
= 70kHz
f
CLK
= 400kHz, f
TEST
= 1kHz
f
CLK
= 400kHz, f
TEST
= 1kHz
f
CLK
= 400kHz, f
TEST
= 2kHz
f
CLK
= 400kHz, f
TEST
= 2kHz
f
CLK
= 400kHz, f
TEST
= 3kHz
f
CLK
= 400kHz, f
TEST
= 3kHz
f
CLK
= 400kHz, f
TEST
= 4kHz
f
CLK
= 400kHz, f
TEST
= 4kHz
V
S
=
±2.375V
V
S
=
±2.375V
V
S
≥
±5V
(Note 3)
±2.375V
≤
V
S
≤
±7.5V
±2.375V
≤
V
S
≤
±7.5V
V
S
=
±2.375V,
f
CLK
= 400kHz
V
S
≥
±5V
(Note 3)
Common Mode Rejection
Power Supply Rejection
Input Voltage Range and Output Voltage Swing
V
S
=
±7.5V
V
CM
= – 5V to 5V
V
S
=
±2.5V
to
±7.5V
V
S
=
±2.375V,
R
L
= 1k
V
S
=
±5V,
R
L
= 1k
V
S
=
±7.5V,
R
L
= 1k
Output Short-Circuit Current
Power Supply Current (Note 2)
±2.375V
≤
V
S
≤
±7.5V
V
S
=
±2.375V
V
S
=
±5V
V
S
=
±7.5V
Power Supply Range
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
– 1.75
– 1.75
– 48.5
– 48.0
– 0.65
– 97.5
– 97.0
– 0.75
– 148.0
– 147.5
– 1.40
– 208.0
– 207.5
– 2.10
TYP
– 1.25
– 0.70
1.00
– 50.0
– 50.0
– 0.25
– 99.5
– 99.5
– 0.50
– 150.5
– 150.5
– 1.00
– 210.0
– 210.0
– 1.80
60
70
±10
±10
40
7
±0.5
±1.0
±0.5
±1.0
MAX
– 0.50
0.10
1.40
– 51.5
– 52.0
0.25
– 101.5
– 102.0
– 0.10
– 152.5
– 153.0
– 0.60
– 212.5
– 213.0
– 1.60
135
±40
±45
UNITS
dB
dB
dB
Deg
Deg
dB
Deg
Deg
dB
Deg
Deg
dB
Deg
Deg
dB
nA
nA
nA
nA
pA/°C
µV/°C
mV
mV
mV
mV
dB
dB
dB
dB
V
V
V
V
V
V
mA
±1.5
±1.5
90
84
80
78
±1.2
±1.1
±3.4
±3.2
±5.4
±5.0
±20
96
90
84
82
±1.4
±3.6
±5.8
14
16
22
23
25
26
±2.375
16
19
26
29
30
33
±8
mA
mA
mA
mA
mA
mA
V
Note 2:
The maximum current over temperature is at 0°C. At 70°C the
maximum current is less than its maximum value at 25°C.
Note 3:
Guaranteed by design and test correlation.
10661fa
3
LTC1066-1
TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency
V
S
=
±7.5V,
f
CLK
/ f
C
= 50:1
10
0
–10
–20
–30
f
CLK
= 500kHz
GAIN (dB)
f
CLK
= 5MHz
GAIN (dB)
–40
–50
–60
–70
–80
–90
–100
–110
1k
10k
100k
FREQUENCY (Hz)
1M
1066-1 G02
GAIN (dB)
–40
–50
–60
–70
–80
–90
–100
–110
1k
10k
100k
FREQUENCY (Hz)
1M
1066-1 G01
V
S
=
±7.5V
T
A
= 25°C
f
CLK
/f
C
= 50:1
COMPENSATION
= 30k, 15pF
f
CLK
= 2.5MHz
Passband Gain and Phase
vs Frequency
3
2
1
0
GAIN (dB)
V
S
=
±7.5V
T
A
= 25°C
GAIN
–1
–2
PHASE
–3
–4
–5
–6
2
4
6
ELLIPTIC RESPONSE
f
C
= 20kHz, f
CLK
= 1MHz
f
CLK
/f
C
= 50:1, PIN 8 AT V
+
R
F
= 20k, C
F
= 1µF
(SEE BLOCK DIAGRAM)
– 60
–120
–180
–240
–300
GAIN (dB)
Passband Gain and Phase
vs Frequency
3
2
1
0
GAIN (dB)
V
S
=
±7.5V
T
A
= 25°C
GAIN
GAIN (dB)
–1
–2
–3
–4
–5
–6
2
4
6
ELLIPTIC RESPONSE
f
C
= 20kHz, f
CLK
/f
C
= 100:1
PIN 8 AT V
–
, R
F
= 20k, C
F
= 1µF
(SEE BLOCK DIAGRAM)
PHASE
– 60
–120
–180
–240
–300
–1
–2
–3
–4
–5
–6
1
V
S
= SINGLE 5V
T
A
= 70°C
f
CLK
/f
C
= 50:1
R
F
= 20k, C
F
= 1µF
RC COMPENSATION
= 15pF IN SERIES
WITH 30kΩ
GAIN (dB)
–360
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
10666-1 G06
4
U W
Gain vs Frequency
V
S
=
±7.5V,
f
CLK
/ f
C
= 100:1
10
0
–10
–20
–30
f
CLK
= 1MHz
f
CLK
= 5MHz
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
Gain vs Frequency
V
S
=
±7.5V,
f
CLK
/ f
C
= 100:1
f
CLK
= 1MHz
f
CLK
= 5MHz
V
S
=
±7.5V
T
A
= 25°C
f
CLK
/f
C
= 100:1
NO COMPENSATION
PIN 8 TO AGND
V
S
=
±7.5V
T
A
= 25°C
f
CLK
/f
C
= 100:1
PIN 8 TO V
–
1k
10k
100k
FREQUENCY (Hz)
1M
1066-1 G03
Passband Gain and Phase
vs Frequency
180
120
60
0
PHASE (DEG)
3
2
1
0
–1
–2
–3
–4
–5
–6
2
4
6
LINEAR PHASE RESPONSE
f
C
= 20kHz, f
CLK
/f
C
= 100:1
PIN 8 AT GND, R
F
= 20k, C
F
= 1µF
(SEE BLOCK DIAGRAM)
GAIN
PHASE
V
S
=
±7.5V
T
A
= 25°C
180
120
60
0
– 60
–120
–180
–240
–300
PHASE (DEG)
–360
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
10666-1 G04
–360
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
10666-1 G05
Passband Gain vs Frequency
and f
CLK
180
120
60
0
PHASE (DEG)
3
2
1
0
A
B
C
A. f
CLK
= 1MHz (GND = 2.5V)
B. f
CLK
= 1.4MHz (GND = 2V)
C. f
CLK
= 1.8MHz (GND = 2V)
Passband Gain vs Frequency
and f
CLK
5
4
3
2
1
0
–1
–2
–3
–4
–5
50
1066-1 G07
V
S
=
±5V,
T
A
= 70°C
f
CLK
/f
C
= 50:1
R
F
= 20k, C
F
= 1µF
RC COMPENSATION
=15pF IN SERIES
WITH 30kΩ
A
A. f
CLK
= 1MHz
B. f
CLK
= 2MHz
C. f
CLK
= 3MHz
D. f
CLK
= 4MHz
1
10
FREQUENCY (kHz)
B
C D
10
FREQUENCY (kHz)
100
1066-1 G08
10661fa
LTC1066-1
TYPICAL PERFOR A CE CHARACTERISTICS
Passband Gain vs Frequency
5
4
3
2
GAIN (dB)
80
60
50
40
30
20
1
0
–1
–2
–3
–4
–5
1
V
S
=
±5V
T
A
= 25°C
f
C
= 20kHz
B
PHASE DIFFERENCE (±DEG)
GROUP DELAY (µs)
V
S
=
±5V,
T
A
= 70°C
f
CLK
/f
C
= 50:1
R
F
= 20k, C
F
= 1µF
RC COMPENSATION
=15pF IN SERIES
WITH 30kΩ
A
A. f
CLK
= 1MHz
B. f
CLK
= 2MHz
C. f
CLK
= 3MHz
D. f
CLK
= 4MHz
10
FREQUENCY (kHz)
THD + Noise vs Input Voltage
–40
–45
T
A
= 25°C
f
IN
= 1kHz
f
CLK
= 1MHz
f
CLK
/f
C
= 50:1
V
S
=
±5V
–40
–45
20 log THD + NOISE (dB)
V
IN
20 log THD + NOISE (dB)
V
IN
)
)
–60
–65
–70
–75
–80
–85
–90
0.1
)
–55
20 log THD + NOISE (dB)
V
IN
–50
(
(
V
S
=
±7.5V
–75
–80
–85
GND PIN 15 AT 2.5V
(
1
INPUT VOLTAGE (V
RMS
)
THD + Noise vs Frequency
–40
–45
V
S
=
±7.5V
V
IN
= 1V
RMS
T
A
= 25°C
f
CLK
= 2.5MHz
f
CLK
/f
C
= 50:1
–40
–45
20 log THD + NOISE (dB)
V
IN
20 log THD + NOISE (dB)
V
IN
–50
–55
–60
–65
–70
–75
–80
–85
–90
1
)
)
–55
–60
–65
–70
20 log THD + NOISE (dB)
V
IN
C
B
A. R
L
=
∞,
C
L
= 100pF
B. R
L
= 1k, C
L
= 100pF
C. R
L
= 200Ω, C
L
= 100pF
10
FREQUENCY (kHz)
A
(
(
–75
–80
–85
–90
50
1066-1 G15
1
FREQUENCY (kHz)
10
20
1066-1 G16
(
)
U W
B
C D
Group Delay vs Frequency
70
A. f
CLK
/f
C
= 50:1 (PIN 8 TO V
+
)
B. f
CLK
/f
C
= 100:1 (PIN 8 TO V
–
)
C. LINEAR PHASE REPONSE
f
CLK
/f
C
= 100:1 (PIN 8 TO GND)
1.25
Phase Matching vs Frequency
PHASE DIFFERENCE BETWEEN
ANY TWO UNITS (SAMPLE OF
50 REPRESENTATIVE UNITS)
V
S
≥
±5V,
T
A
= 25°C
f
CLK
≤
2.5MHz
A
B
0.50
A. ELLIPTIC RESPONSE
f
CLK
/f
C
= 50:1 (PIN 8 to V
+
)
B. LINEAR PHASE RESPONSE
f
CLK
/f
C
= 100:1 (PIN8 TO GND)
0.6
0.8
0.4
FREQUENCY (f
CUTOFF
/FREQUENCY)
1.0
A
1.00
0.75
C
0.25
100
1066-1 G08
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1066-1 G10
0
0.2
1066-1 G11
THD + Noise vs Input Voltage
–40
f
IN
= 1kHz
V
S
= SINGLE 5V
f
CLK
= 1MHz
f
CLK
/f
C
= 50:1
T
A
= 25°C
GND PIN 15 AT 2V
–45
–50
–55
–60
–65
–70
–75
–80
–85
–90
1
INPUT VOLTAGE (V
RMS
)
2
1066-1 G13
THD + Noise vs Frequency
V
S
=
±7.5V
V
IN
= 1V
RMS
T
A
= 25°C
f
CLK
= 2.5MHz
f
CLK
/f
C
= 50:1
(5 REPRESENTATIVE
UNITS)
–50
–55
–60
–65
–70
5
1066-1 G12
–90
0.1
1
10
FREQUENCY (kHz)
50
1066-1 G14
THD + Noise vs Frequency
V
S
=
±5V
V
IN
= 1V
RMS
T
A
= 25°C
f
CLK
= 1MHz
f
CLK
/f
C
= 50:1
(5 REPRESENTATIVE
UNITS)
–40
–45
–50
–55
–60
–65
–70
–75
–80
–85
–90
THD + Noise vs Frequency
V
S
= SINGLE 5V
V
IN
= 0.5V
RMS
T
A
= 25°C
f
CLK
= 1MHz
f
CLK
/f
C
= 50:1
(5 REPRESENTATIVE
UNITS)
–50
1
FREQUENCY (kHz)
10
20
1066-1 G17
10661fa
5
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