LTC1064-7
Linear Phase, 8th Order
Lowpass Filter
FEATURES
■
■
■
■
■
■
■
■
■
DESCRIPTIO
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
Available in 14-Pin DIP and 16-Pin SO Wide
Packages
The LTC
®
1064-7 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 while 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Data Communication Filters
Time Delay Networks
Phase-Matched Filters
TYPICAL APPLICATIO
1
V
IN
2
3
7.5V
4
5
6
7
LTC1064-7
14
13
12
11
10
9
8
80kHz Linear Phase Lowpass Filter
–7.5V
7.5V
V
OUT
1064-7 TA01
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
CLK = 4MHz
V
S
=
±7.5V
f
CLK
= 4MHz
RATIO = 50:1
U
Eye Diagram
1µs/DIV
1064-7 TA02
U
U
10647fb
1
LTC1064-7
ABSOLUTE
AXI U
RATI GS
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
–
11 f
CLK
10 50/100
9
8
V
OUT
NC
ORDER PART
NUMBER
LTC1064-7CN
N PACKAGE
14-LEAD PLASTIC DIP
T
JMAX
= 110°C,
θ
JA
= 65°C/W (N)
J PACKAGE 14-LEAD CERAMIC DIP
T
JMAX
= 150°C,
θ
JA
= 65°C/W (J)
OBSOLETE PACKAGE
Consider the N Package as an Alternate Source
LTC1064-7CJ
LTC1064-7MJ
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.
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.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. The filter cutoff frequency is abbreviated as f
CUTOFF
or f
C
.
PARAMETER
Passband Gain
Gain at 0.5 f
CUTOFF
Gain at 0.75 f
CUTOFF
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 2)
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
MIN
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
2
U
U
W
W W
U
W
(Note 1)
Operating Temperature Range
LTC1064-7C ....................................... – 40°C to 85°C
LTC1064-7M
OBSOLETE ..............
– 55°C to 125°C
Lead Temperature (Soldering, 10 sec)................. 300°C
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
V
OUT
ORDER PART
NUMBER
LTC1064-7CSW
SW PACKAGE
16-LEAD PLASTIC SO (WIDE)
T
JMAX
= 110°C,
θ
JA
= 85°C/W
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
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
10647fb
– 0.60
– 0.90
– 1.30
– 2.0
– 4.50
– 5.75
– 36.5
– 37.0
– 6.5
– 0.9
– 4.5
●
●
422
414
437
429
LTC1064-7
ELECTRICAL CHARACTERISTICS
PARAMETER
Phase Nonlinearity
(Notes 2, 4)
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
=
±7.5V,
R
L
= 10k, 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. The filter cutoff frequency is abbreviated as f
CUTOFF
or f
C
.
CONDITIONS
(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
≤
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
V
S
=
±7.5V,
T
A
= 25°C
Power Supply Range
MIN
TYP
±1.0
±1.0
MAX
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
●
●
±
2.0
±
2.0
Group Delay (t
d
)
t
d
= (F /360)(1/ f
C
)
(Note 3)
Group Delay Deviation
(Notes 3, 4)
●
●
58.6
115.0
59.7
±
0.5
117.0
±
1.0
59.7
117.0
±1.0
±1.0
60.7
119.0
●
●
±
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
●
●
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
70
±220
●
●
17
●
±2.375
22
22
26
28
28
32
±8
10647fb
3
LTC1064-7
ELECTRICAL CHARACTERISTICS
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Input frequencies, f, are linearly phase shifted through the filter as
long as f
≤
f
C
; f
C
= cutoff frequency.
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 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 the calculation of the phase at a given frequency.
Example: The phase shift at 14kHz of the LTC1064-7 shown in Figure 1 is:
phase shift = 180° – 430° (14kHz/20kHz)
±
nonlinearity = –121°
±
1% or
–121°
±
1.20°.
Note 3:
Group delay and group delay deviation are calculated from the
measured phase factor and phase deviation specifications.
Note 4:
Phase deviation and group delay deviation for LTC1064-7MJ is
±4%.
Note 5:
The AC swing is typically 11V
P-P
, 7V
P-P
, 2.8V
P-P
, with
±7.5V, ±5V,
±2.5V
Supply respectively. For more information refer to the THD + Noise
vs Input graphs.
180
90
0
–90
–180
–270
–360
0
2
4
6 8 10 12 14 16 18 20
FREQUENCY (kHz)
1164-7 F01
f
CLK
= 1MHz
RATIO = 50:1
Figure 1. Phase Response in the Passband (Note 2)
PHASE (DEG)
10647fb
4
LTC1064-7
TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency
10
0
–10
–20
–30
100:1
50:1
PHASE FACTOR
475
465
PHASE FACTOR
455
445
435
25°C
485
V
S
= ±5V
(f
CLK
/f
C
) = 50:1
70°C
465
70°C
455
445
25°C
435
0°C
425
415
425
415
0.5
1.0
1.5
2.5
2.0
f
CLK
(MHz)
3.0
3.5
0.5
1.0
1.5
2.5
2.0
f
CLK
(MHz)
3.0
3.5
0°C
GAIN (dB)
–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
440
PHASE FACTOR
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
GAIN (dB)
–1
–2
–3
–4
–5
–6
2
4
6
PHASE
– 60
–120
–180
–240
–300
GAIN (dB)
U W
Phase Factor vs f
CLK
(Typical Unit)
485
475
Phase Factor vs f
CLK
(Typical Unit)
V
S
= ±5V
(f
CLK
/f
C
) = 100:1
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
1.5
2.0
1064-7 G05
Passband Gain and Phase
180
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)
V
S
= ±5V
f
CLK
= 1MHz
(f
CLK
/f
C
) = 50:1
120
60
0
PHASE (DEG)
GAIN
–360
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1064-7 G06
10647fb
5
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