LTC1064-7
Linear Phase, 8th Order
Lowpass Filter
FEATURES
s
s
s
s
s
DESCRIPTIO
s
s
s
Steeper Roll-Off Than 8th Order Bessel Filters
f
CUTOFF
up to 100kHz
Phase Equalized Filter in 14-Pin Package
Phase and Group Delay Response Fully Tested
Transient Response Exhibits 5% Overshoot and
No Ringing
Wide Dynamic Range
72dB THD or Better Throughout a 50kHz Passband
No External Components Needed
The LTC1064-7 is a clock-tunable monolithic 8th order
lowpass filter with linear passband phase and flat group
delay. The amplitude response approximates a maximally
flat passband whilte it exhibits steeper roll-off than an
equivalent 8th order Bessel filter. For instance, at twice the
cutoff frequency the filter attains 34dB attenuation (vs
12dB for Bessel), while at three times the cutoff frequency
the filter attains 68dB attenuation (vs 30dB for Bessel).
The cutoff frequency of the LTC1064-7 is tuned via an
external TTL or CMOS clock.
The LTC1064-7 features wide dynamic range. With single
5V supply, the S/N + THD is 76dB. Optimum 92dB S/N is
obtained with
±7.5V
supplies.
The clock-to-cutoff frequency ratio of the LTC1064-7 can
be set to 50:1 (pin 10 to V
+
) or 100:1 (pin 10 to V
–
).
When the filter operates at clock-to-cutoff frequency ratio
of 50:1, the input is double-sampled to lower the risk of
aliasing.
The LTC1064-7 is pin-compatible with the LTC1064-X
series, LTC1164-7 and LTC1264-7.
APPLICATI
s
s
s
S
Data Communication Filters
Time Delay Networks
Phase-Matched Filters
TYPICAL APPLICATI
1
V
IN
2
3
7.5V
4
5
6
7
LTC1064-7
80kHz Linear Phase Lowpass Filter
14
13
12
11
10
9
8
1064-7 TA01
–7.5V
CLK = 4MHz
V
OUT
NOTE: THE POWER SUPPLIES SHOULD BE BYPASSED BY A
0.1µF CAPACITOR CLOSE TO THE PACKAGE AND ANY PRINTED
CIRCUIT BOARD ASSEMBLY SHOULD MAINTAIN A DISTANCE
OF AT LEAST 0.2 INCHES BETWEEN ANY OUTPUT OR INPUT
PIN AND THE f
CLK
LINE.
1V/DIV
7.5V
V
S
=
±7.5V
f
CLK
= 4MHz
RATIO = 50:1
U
Eye Diagram
1µs/DIV
1064-7 TA02
UO
UO
1
LTC1064-7
ABSOLUTE
AXI U
RATI GS
Operating Temperature Range
LTC1064-7C ....................................... – 40°C to 85°C
LTC1064-7M .................................... – 55°C to 125°C
Lead Temperature (Soldering, 10 sec)................. 300°C
Total Supply Voltage (V
+
to V
–
) .......................... 16.5V
Power Dissipation............................................. 400mW
Burn-In Voltage ................................................... 16.5V
Voltage at Any Input ..... (V
–
– 0.3V)
≤
V
IN
≤
(V
+
+ 0.3V)
Storage Temperature Range ................ – 65°C to 150°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
NC
V
IN
GND
V
+
GND
LP (A)
INV (A)
1
2
3
4
5
6
7
14 R
IN
(A)
13 NC
12
V
–
ORDER PART
NUMBER
LTC1064-7CN
LTC1064-7CJ
LTC1064-7MJ
11 f
CLK
10 50/100
9
8
V
OUT
NC
J PACKAGE
14-LEAD CERAMIC DIP
N PACKAGE
14-LEAD PLASTIC DIP
T
JMAX
= 150°C,
θ
JA
= 65°C/W (J)
T
JMAX
= 110°C,
θ
JA
= 65°C/W (N)
ELECTRICAL CHARACTERISTICS
PARAMETER
Passband Gain
Gain at 0.5 f
CUTOFF
(Note 4)
Gain at 0.75 f
CUTOFF
(Note 1)
Gain at f
CUTOFF
Gain at 2 f
CUTOFF
Gain with f
CLK
= 20kHz
Gain with f
CLK
= 400kHz, V
S
=
±2.375V
Phase Factor (F )
Phase = 180° –
F
(f/f
C
)
(Note 1)
V
S
=
±7.5V,
R
L
= 10k, T
A
= 25°C, f
CUTOFF
= 10kHz or 20kHz, f
CLK
= 1MHz, TTL or CMOS level (maximum clock rise and fall time
≤
1µs)
and all gain measurements are referenced to passband gain, unless otherwise specified.
CONDITIONS
0.1Hz
≤
f
≤
0.25 f
CUTOFF
f
TEST
= 5kHz, (f
CLK
/f
C
) = 50:1
f
TEST
= 10kHz, (f
CLK
/f
C
) = 50:1
f
TEST
= 5kHz, (f
CLK
/f
C
) = 100:1
f
TEST
= 15kHz, (f
CLK
/f
C
) = 50:1
f
TEST
= 20kHz, (f
CLK
/f
C
) = 50:1
f
TEST
= 10kHz, (f
CLK
/f
C
) = 100:1
f
TEST
= 40kHz, (f
CLK
/f
C
) = 50:1
f
TEST
= 20kHz, (f
CLK
/f
C
) = 100:1
f
TEST
= 200Hz, (f
CLK
/f
C
) = 100:1
f
TEST
= 4kHz, (f
CLK
/f
C
) = 50:1
f
TEST
= 8kHz, (f
CLK
/f
C
) = 50:1
0.1Hz
≤
f
≤
f
CUTOFF
(f
CLK
/f
C
) = 50:1
(f
CLK
/f
C
) = 100:1
(f
CLK
/f
C
) = 50:1
(f
CLK
/f
C
) = 100:1
(f
CLK
/f
C
) = 50:1
(f
CLK
/f
C
) = 100:1
(f
CLK
/f
C
) = 50:1
(f
CLK
/f
C
) = 100:1
MIN
q
q
q
q
q
q
q
q
Phase Nonlinearity
(Notes 1, 3)
2
U
U
W
W W
U
W
TOP VIEW
NC 1
V
IN
2
GND 3
V
+
4
GND 5
NC 6
LP (A) 7
INV (A) 8
16 R
IN
(A)
15 NC
14 V
–
13 NC
12 f
CLK
11 50/100
10 NC
9
S PACKAGE
16-LEAD PLASTIC SOL
T
JMAX
= 110°C,
θ
JA
= 85°C/W
ORDER PART
NUMBER
LTC1064-7CS
V
OUT
TYP
0.10
– 0.35
– 0.35
–1.0
– 3.4
– 4.5
– 34.0
– 34.5
– 4.3
– 0.3
– 3.3
430
±
2.0
421
±
2.5
430
421
±1.0
±1.0
MAX
0.65
0.15
1.25
– 0.35
– 2.50
– 3.75
– 31.75
– 31.75
– 3.5
0.25
– 2.00
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
Deg
Deg
Deg
Deg
%
%
%
%
– 0.60
– 0.90
– 1.30
– 2.0
– 4.50
– 5.75
– 36.5
– 37.0
– 6.5
– 0.9
– 4.5
q
q
422
414
437
429
q
q
±
2.0
±
2.0
LTC1064-7
ELECTRICAL CHARACTERISTICS
V
S
=
±7.5V,
R
L
= 10k, T
A
= 25°C, f
CUTOFF
= 10kHz or 20kHz, f
CLK
= 1MHz, TTL or CMOS level (maximum clock rise and fall time
≤
1µs)
and all gain measurements are referenced to passband gain, unless otherwise specified.
PARAMETER
Group Delay (t
d
)
t
d
= (F /360)(1/ f
C
)
(Note 2)
Group Delay Deviation
(Notes 2, 3)
CONDITIONS
(f
CLK
/f
C
) = 50:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 100:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 50:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 100:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 50:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 100:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 50:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 100:1, f
≤
f
CUTOFF
(f
CLK
/f
C
) = 50:1
(f
CLK
/f
C
) = 100:1
V
S
= 5V (AGND = 2V)
V
S
=
±5V
V
S
=
±7.5V
50:1
V
S
=
±2.5V
V
S
=
±5V
V
S
=
±7.5V
V
S
=
±2.375V
V
S
=
±5V
V
S
=
±7.5V
50:1, V
S
=
±5V
100:1, V
S
=
±5V
50:1, V
S
=
±5V
100:1, V
S
=
±5V
V
S
=
±2.375V,
T
A
= 25°C
V
S
=
±5V,
T
A
= 25°C
q
MIN
q
q
58.6
115.0
TYP
59.7
±
0.5
117.0
±
1.0
59.7
117.0
±1.0
±1.0
MAX
60.7
119.0
q
q
±2.0
±2.0
Input Frequency Range (Table 9)
Maximum f
CLK
Clock Feedthrough (f
≥
f
CLK
)
Wideband Noise
(1Hz
≤
f
≤
f
CLK
)
Input Impedance
Output DC Voltage Swing
(Note 5)
Output DC Offset
Output DC Offset TempCo
Power Supply Current
q
q
25
±1.0
±2.1
±3.0
<f
CLK
<f
CLK
/2
2.0
3.5
5.0
200
95
±
5%
105
±
5%
115
±
5%
40
±1.2
±3.2
±5.0
±150
±150
±200
±200
11
14
17
70
±220
q
V
S
=
±7.5V,
T
A
= 25°C
q
Power Supply Range
±2.375
22
22
26
28
28
32
±8
UNITS
µs
µs
µs
µs
%
%
%
%
kHz
kHz
MHz
MHz
MHz
µV
RMS
µV
RMS
µV
RMS
µV
RMS
kΩ
V
V
V
mV
mV
µV/°C
µV/°C
mA
mA
mA
mA
mA
mA
V
The
q
denotes specifications which apply over the full operating temperature range.
180
Note 1:
Input frequencies, f, are linearly phase shifted through the filter as long as f
≤
f
CLK
= 1MHz
f
C
; f
C
= cutoff frequency.
RATIO = 50:1
90
Figure 1 curve shows the typical phase response of an LTC1064-7 operating at f
CLK
=
1MHz, ratio = 50:1, f
C
= 20kHz and it closely matches an ideal straight line. The phase
0
shift is described by: phase shift = 180° –
F
(f/f
C
); f
≤
f
C
.
F
is arbitrarily called the “phase factor” expressed in degrees. The phase factor allows
–90
the calculation of the phase at a given frequency. Example: The phase shift at 14kHz of
the LTC1064-7 shown in Figure 1 is:
–180
phase shift = 180° – 430° (14kHz/20kHz)
±
nonlinearity = –121°
±
1% or
–121°
±
1.20°.
–270
Note 2:
Group delay and group delay deviation are calculated from the measured phase
–360
factor and phase deviation specifications.
0 2 4
6 8 10 12 14 16 18 20
Note 3:
Phase deviation and group delay deviation for LTC1064-7MJ is
±4%.
FREQUENCY (kHz)
1164-7 F01
Note 4:
The filter cutoff frequency is abbreviated as f
CUTOFF
or f
C
.
Note 5:
The AC swing is typically 11V
P-P
, 7V
P-P
, 2.8V
P-P
, with
±7.5V, ±5V, ±2.5V
Figure 1. Phase Response in the Passband (Note 1)
Supply respectively. For more information refer to the THD + Noise vs Input graphs.
PHASE (DEG)
3
LTC1064-7
TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency
10
0
–10
–20
–30
GAIN (dB)
100:1
PHASE FACTOR
PHASE FACTOR
–40
–50
–60
–70
–80
–90
–100
–110
0.1
V
S
= ±5V
f
CLK
= 1MHz
T
A
= 25°C
1
10
FREQUENCY (kHz)
100
1064-7 G01
Phase Factor vs f
CLK
(Min and
Max Representative Units)
445
V
S
= ±5V
T
A
= 25°C
(f
CLK
/f
C
) = 50:1
PHASE FACTOR
440
PHASE FACTOR
435
430
425
420
0.5
1.0
1.5
2.5
2.0
f
CLK
(MHz)
3.0
3.5
Passband Gain and Phase
3
2
1
0
V
S
= ±5V
f
CLK
= 1MHz
(f
CLK
/f
C
) = 50:1
180
120
60
0
GAIN
– 60
–120
PHASE
–180
–240
–300
2
4
6
–360
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1064-7 G06
GAIN (dB)
GAIN (dB)
–1
–2
–3
–4
–5
–6
4
U W
50:1
Phase Factor vs f
CLK
(Typical Unit)
485
475
465
455
445
435
0°C
425
415
0.5
1.0
1.5
2.5
2.0
f
CLK
(MHz)
3.0
3.5
425
415
25°C
V
S
= ±5V
(f
CLK
/f
C
) = 50:1
70°C
465
485
475
Phase Factor vs f
CLK
(Typical Unit)
V
S
= ±5V
(f
CLK
/f
C
) = 100:1
70°C
455
445
25°C
435
0°C
0.5
1.0
1.5
2.5
2.0
f
CLK
(MHz)
3.0
3.5
1064-7 G02
1064-7 G03
Phase Factor vs f
CLK
(Min and
Max Representative Units)
445
V
S
= 5V
T
A
= 25°C
PINS 3, 5 AT 2V
(f
CLK
/f
C
) = 50:1
440
435
430
425
420
0.5
1.0
f
CLK
(MHz)
1064-7 G04
1064-7 G05
1.5
2.0
Passband Gain and Phase
3
2
1
0
–1
GAIN
–2
PHASE
–3
–4
–5
–6
2
4
6
–120
–180
–240
–300
–360
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1064-7 G07
180
V
S
= ±5V
f
CLK
= 2MHz
(f
CLK
/f
C
) = 100:1
120
60
0
– 60
PHASE (DEG)
PHASE (DEG)
LTC1064-7
TYPICAL PERFOR A CE CHARACTERISTICS
Passband Gain vs Frequency
and f
CLK
5
4
3
2
V
S
= ±7.5V
T
A
= 25°C
(f
CLK
/f
C
) = 50:1
A. f
CLK
= 1MHz
B. f
CLK
= 2MHz
C. f
CLK
= 3MHz
D. f
CLK
= 4MHz
E. f
CLK
= 5MHz
5
4
3
2
V
S
= ±7.5V
(f
CLK
/f
C
) = 50:1
A. f
CLK
= 1MHz
B. f
CLK
= 2MHz
C. f
CLK
= 3MHz
D. f
CLK
= 4MHz
E. f
CLK
= 5MHz
GAIN (dB)
GAIN (dB)
GAIN (dB)
1
0
–1
–2
–3
–4
–5
10
100
10
FREQUENCY (kHz)
1000
1064-7 G08
D
A
B C
E
Passband Gain vs Frequency
and f
CLK
5
4
3
2
V
S
= SINGLE 5V
T
A
= 25°C
(f
CLK
/f
C
) = 50:1
A. f
CLK
= 0.5MHz
B. f
CLK
= 1.0MHz
C. f
CLK
= 1.5MHz
D. f
CLK
= 2.0MHz
5
4
3
2
DELAY (µs)
GAIN (dB)
0
–1
–2
A
–3
–4
–5
1
10
FREQUENCY (kHz)
100
1064-7 G11
GAIN (dB)
1
B
C D
–3
–4
–5
1
Delay vs Frequency and f
CLK
250
A
200
V
S
= ±5V
T
A
= 25°C
(f
CLK
/f
C
) = 100:1
THD + NOISE (dB)
DELAY (µs)
150
A. f
CLK
= 0.5MHz
B. f
CLK
= 1.5MHz
C. f
CLK
= 2.5MHz
D. f
CLK
= 3.5MHz
B
THD + NOISE (dB)
100
50 C
D
0
1
6
11
26
16
21
FREQUENCY (kHz)
31
36
U W
1064-7 G14
Passband Gain vs Frequency and
f
CLK
at T
A
= 85°C
5
4
3
2
1
0
–1
–2
–3
–4
–5
1
100
10
FREQUENCY (kHz)
1000
1064-7 G09
Passband Gain vs Frequency and
f
CLK
at T
A
= 85°C
V
S
= ±5V
(f
CLK
/f
C
) = 50:1
A. f
CLK
= 0.5MHz
B. f
CLK
= 1.5MHz
C. f
CLK
= 2.5MHz
D. f
CLK
= 3.5MHz
1
0
–1
–2
–3
–4
–5
A
B C
E
D
A
B
C D
1
10
FREQUENCY (kHz)
100
1064-7 G10
Passband Gain vs Frequency and
f
CLK
at T
A
= 85°C
125
V
S
= SINGLE 5V
(f
CLK
/f
C
) = 50:1
A. f
CLK
= 0.5MHz
B. f
CLK
= 1.0MHz
C. f
CLK
= 1.5MHz
D. f
CLK
= 2.0MHz
Delay vs Frequency and f
CLK
A
100
V
S
= ±5V
T
A
= 25°C
(f
CLK
/f
C
) = 50:1
A. f
CLK
= 0.5MHz
B. f
CLK
= 1.5MHz
C. f
CLK
= 2.5MHz
D. f
CLK
= 3.5MHz
B
C
D
0
1
0
–1
–2
A
B
C D
75
50
25
10
FREQUENCY (kHz)
100
1064-7 G12
2
12
22
52
32
42
FREQUENCY (kHz)
62
72
1064-7 G13
THD + Noise vs Frequency
–40
–45
–50
–55
–60
–65
–70
–75
–80
–85
–90
1
FREQUENCY (kHz)
1064-7 G15
THD + Noise vs Frequency
–40
–45
–50
–55
–60
–65
–70
–75
–80
–85
–90
V
S
= ±7.5V
V
IN
= 1V
RMS
f
CLK
= 2.5MHz
(f
CLK
/f
C
) = 50:1
(100k RESISTOR
PIN 9 TO V
–
)
V
S
= ±7.5V
V
IN
= 2V
RMS
f
CLK
= 1MHz
(f
CLK
/f
C
) = 50:1
(100k RESISTOR
PIN 9 TO V
–
)
10
20
1
10
FREQUENCY (kHz)
50
1064-7 G16
5
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