LTC1064-4
Low Noise, 8th Order, Clock
Sweepable Cauer Lowpass Filter
FEATURES
■
■
■
DESCRIPTIO
■
■
■
■
■
8th Order Filter in a 14-Pin Package
80dB or More Stopband Attenuation at 2
×
f
CUTOFF
50:1, f
CLK
to f
CUTOFF
Ratio (Cauer)
100:1, f
CLK
to f
–3dB
Ratio (Transitional)
135µV
RMS
Total Wideband Noise
0.03% THD or Better
100kHz Maximum f
CUTOFF
Frequency
Operates up to
±8V
Power Supplies
Input Frequency Range up to 50 Times the Filter
Cutoff Frequency
APPLICATIO S
■
■
■
The LTC
®
1064-4 is an 8th order, clock sweepable Cauer
lowpass switched capacitor filter. An external TTL or
CMOS clock programs the value of the filter’s cutoff
frequency. With Pin 10 at V
+
, the f
CLK
to f
CUTOFF
ratio is
50:1; the filter has a Cauer response and with compensa-
tion the passband ripple is
±0.1dB.
The stopband attenu-
ation is 80dB at 2
×
f
CUTOFF
. Cutoff frequencies up to
100kHz can be achieved. With Pin 10 at V
–
, the f
CLK
to
f
–3dB
ratio is 100:1, the filter has a transitional Butterworth-
Cauer response with lower noise and lower delay
nonlinearity than the Cauer response. The stopband
attenuation at 2.5
×
f
–3dB
is 92dB. Cutoff frequencies up to
50kHz can be achieved.
The LTC1064-4 features low noise and low harmonic
distortion even when input voltages up to 3V
RMS
are
applied. The LTC1064-4 overall performance competes
with equivalent multiple op amp active realizations. The
LTC1064-4 is pin compatible with the LTC1064-1,
LTC1064-2 and LTC1064-3.
The LTC1064-4 is manufactured using Linear Technology’s
enhanced LTCMOS
TM
silicon gate process.
Antialiasing Filters
Telecom Filters
Sinewave Generators
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTCMOS is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
1
V
IN
2
3
8V
0.1µF
INV C
V
IN
R(h, I)
COMP2*
8th Order Clock Sweepable Lowpass Elliptic Filter
14
13
–8V
0.1µF
20
0
–20
–40
–60
Frequency Response
T
A
= 25°C
f
CLK
= 5MHz, 50:1
C
COMP1
= 30pF, C
COMP2
= 18pF
12
V
–
AGND
4
+
LTC1064-4
11
CLOCK
f
CLK
V
(TTL,
≤5MHz)
5
10
+ –
50/100
AGND
V /V
6
7
COMP1*
INV A
V
OUT
NC
9
8
V
OUT
V
OUT
/V
IN
(dB)
f
CLK
= 2MHz, 50:1
–80
–100
f
CLK
= 1MHz, 100:1
1k
10k
100k
FREQUENCY (Hz)
1M
1064-4 TA01b
1064 TA01
* FOR FREQUENCIES ABOVE 20kHz AND MINIMUM PASSBAND RIPPLE REFER
TO THE PIN DESCRIPTION SECTION FOR COMPENSATION GUIDELINES.
NOTE:THE POWER SUPPLIES SHOULD BE BYPASSED BY A 0.1µF CAPACITOR
CLOSE TO THE PACKAGE. BYPASSING PIN 10 WITH 0.1µF CAPACITOR
REDUCES CLOCK FEEDTHROUGH. THE CONNECTION BETWEEN PINS 7
AND 14 SHOULD BE PHYSICALLY DONE UNDER THE PACKAGE.
U
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U
U
1
LTC1064-4
ABSOLUTE
AXI U
RATI GS
Total Supply Voltage (V
+
to V
–
) ............................ 16.5V
Input Voltage at Any Pin ...... V
–
–0.3V
≤
V
IN
≤
V
+
+0.3V
Power Dissipation .............................................. 400mW
Storage Temperature Range ................. – 65°C to 150°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
INV C
V
IN
AGND
V
+
AGND
COMP1
INV A
1
2
3
4
5
6
7
14 R(h, I)
13 COMP2
–
12 V
ORDER PART
NUMBER
INV C 1
LTC1064-4CN
11 f
CLK
10 RATIO
9
8
V
OUT
NC
N PACKAGE
14-LEAD PDIP
T
JMAX
= 110°C,
θ
JA
= 70°C/W
J PACKAGE
14-LEAD CERDIP
OBSOLETE PACKAGE
Consider the N14 Package for Alternate Source
LTC1064-4MJ
LTC1064-4CJ
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
Passband Gain
Gain TempCo
Passband Edge Frequency, f
C
Gain at f
C
–3dB Frequency
Passband Ripple (Note 2)
Stopband Attenuation
Stopband Attenuation
Input Frequency Range
Output Voltage Swing and
Operating Input Voltage Range
Total Harmonic Distortion
Wideband Noise
CONDITIONS
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
=
±7.5V,
50:1, f
CLK
= 1MHz, f
C
= 20kHz, R1 = 10k, TTL clock input
level unless otherwise specified.
MIN
●
Referenced to 0dB, 1Hz to 0.05f
CUTOFF
Referenced to Passband Gain, f
C
= 20kHz
50:1 (Cauer Response)
100:1 (Transitional Response)
0.1f
C
to 0.95f
C
Referenced to Passband Gain
At 1.7f
CUTOFF
At 2f
CUTOFF
50:1, Pin 10 at V
+
100:1, Pin 10 at V
–
V
S
=
±2.37V
V
S
=
±5V
V
S
=
±7.5V
V
S
=
±5V,
Input = 1V
RMS
at 1kHz
V
S
=
±7.5V,
Input = 3V
RMS
at 1kHz
V
S
=
±5V,
Input = GND 1Hz to 999kHz
V
S
=
±7.5V,
Input = GND 1Hz to 999kHz
2
U
U
W
W W
U
W
(Note 1)
Lead Temperature (Soldering, 10 sec).................. 300°C
Operating Temperature Range
LTC1064-4M
(OBSOLETE)
............... – 55°C to 125°C
LTC1064-4C ....................................... – 40°C to 85°C
TOP VIEW
16 R(h, I)
15 COMP2
14 V
–
13 NC
12 f
CLK
11 RATIO
10 NC
9 V
OUT
ORDER PART
NUMBER
LTC1064-4CSW
V
IN
2
AGND 3
V
+
4
AGND 5
NC 6
COMP1 7
INV A 8
SW PACKAGE
16-LEAD PLASTIC (WIDE) SO
T
JMAX
= 150°C,
θ
JA
= 90°C/W
TYP
0.0002
20
±
1%
MAX
0.1
UNITS
dB
dB/°C
kHz
dB
kHz
kHz
dB
dB
dB
kHz
kHz
V
V
V
–0.5
●
–0.4
21.5
10
0.7
●
●
–0.15
–56
0
0
0.6
–60
–80
f
CLK
f
CLK
/2
●
●
●
±1.1
±3.1
±5.0
0.015
0.03
120
135
%
%
µV
RMS
µV
RMS
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LTC1064-4
ELECTRICAL CHARACTERISTICS
PARAMETER
Output DC Offset
Output DC Offset TempCo
Input Impedance
Output Impedance
Output Short-Circuit Current
Clock Feedthrough
Maximum Clock Frequency
Power Supply Current
f
OUT
= 10kHz
Source/Sink
Input = GND
CONDITIONS
V
S
=
±7.5V
V
S
=
±5V
V
S
=
±7.5V
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
=
±7.5V,
50:1, f
CLK
= 1MHz, f
C
= 20kHz, R1 = 10k, TTL clock input
level unless otherwise specified.
MIN
TYP
±
50
–100
–200
9
13
2
3/1
200
5
●
●
MAX
±160
UNITS
mV
µV/°C
µV/°C
kΩ
Ω
mA
µV
RMS
MHz
mA
mA
mA
mA
mA
V
V
S
=
±7.5V,
50% Duty Cycle (Note 3)
V
S
=
±2.37V,
f
CLK
= 1MHz
V
S
=
±5V,
f
CLK
= 1MHz
V
S
=
±7.5V,
f
CLK
= 1MHz
●
11
14
17
22
23
26
28
32
±8
Power Supply Voltage Range
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
●
±2.37
Note 2:
For tighter passband ripple specifications please consult with
LTC’s marketing.
Note 3:
Not tested, guaranteed by design.
TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency
15
0
–15
V
S
=
±7.5V
T
A
= 25°C
f
CLK
= 2MHz, 50:1
–45
0
45
90
135
180
225
270
315
360
405
450
V
S
=
±7.5V
T
A
= 25°C
f
C
= 20kHz
f
CLK
= 1MHz, 50:1
GROUP DELAY (µs)
PHASE SHIFT (DEG)
GAIN (dB)
–30
–45
–60
–75
–90
–105
10k
100k
FREQUENCY (Hz)
U W
1064-4 G01
Passband Phase Shift vs
Frequency
220
200
180
160
140
120
100
80
60
40
20
0
0
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1064-4 G02
Passband Group Delay
V
S
=
±7.5V
T
A
= 25°C
f
C
= 20kHz
f
CLK
= 1MHz, 50:1
1M
0
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1064-4 G03
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3
LTC1064-4
TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency with
Compensation
5
T
A
= 125°C
0
–5
T
A
= 25°C
PHASE MATCH (±DEG)
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
V
S
=
±7.5V
f
C
= 20kHz
f
CLK
= 1MHz, 50:1
50 UNIT SAMPLE (T
A
= 25°C TO 125°C)
DISTORTION (%)
GAIN (dB)
–10
–15
–20
–25
–30
V
S
=
±7.5V
f
CLK
= 5MHz
RATIO = 50:1
FOR COMPENSATION INFORMATION
SEE PIN DESCRIPTION SECTION
100k
FREQUENCY (Hz)
1M
1064-4 G04
–35
10k
Power Supply Current vs Power
Supply Voltage
48
44
f
CLK
= 1MHz
POWER SUPPLY CURRENT (mA)
40
36
32
28
20
16
12
8
4
0
0 2 4 6 8 10 12 14 16 18 20 22 24
TOTAL POWER SUPPLY VOLTAGE (V)
1064-4 G07
T
A
= 25°C
T
A
= 125°C
2V/DIV
24
4
U W
V
+
V
–
Device to Device Phase Matching
1.0
Total Harmonic Distortion
f
CLK
= 1MHz, 50:1
f
CUTOFF
= 20kHz
V
S
=
±5V
0.1
V
S
=
±2.37V
V
S
=
±7.5V
0.01
0.1
1
INPUT LEVEL (V
RMS
)
10
1064-4 G06
0
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1064-4 G05
Transient Response
f
CLK
= 1MHz, Ratio = 50:1,
f
C
= 20kHz, V
S
=
±7.5V,
1kHz
Square Wave Input
T
A
= –55°C
0.1ms/DIV
Table 1. Wideband Noise (µV
RMS
). Input Grounded, f
CLK
= 1MHz
V
S
=
±2.37V
Pin 10 to
f
CLK
/f
CUTOFF
50:1
100:1
Noise
µV
RMS
120
100
V
S
=
±5V
Noise
µV
RMS
135
120
V
S
=
±7.5V
Noise
µV
RMS
145
130
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LTC1064-4
TYPICAL PERFOR A CE CHARACTERISTICS
Table 2. Gain/Phase, Pin 10 at V
+
, Typical Response
f
CUTOFF
= 1kHz, V
S
=
±5V,
T
A
= 25°C, f
CLK
= 50kHz, Ratio = 50:1
FREQUENCY(kHz)
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1.800
2.000
GAIN (dB)
– 0.075
– 0.050
0.020
0.060
0.090
– 15.640
– 34.700
– 51.700
– 68.600
– 84.110
PHASE (deg)
–59.990
–122.400
169.300
88.500
–26.100
–175.100
126.500
87.600
38.400
–47.860
Table 3. Gain/Delay, Pin 10 at V
+
, Typical Response
f
CUTOFF
= 1kHz, V
S
=
±5V,
T
A
= 25°C, f
CLK
= 50kHz, Ratio = 50:1
FREQUENCY(kHz)
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
1.200
GAIN (dB)
– 0.074
– 0.070
– 0.050
– 0.020
0.020
0.050
0.060
0.120
0.090
– 5.020
– 15.650
DELAY (ms)
0.844
0.867
0.899
0.949
1.021
1.122
1.275
1.592
2.160
2.070
1.288
Table 5. Gain/Delay, Pin 10 at V
–
, Typical Response
f
–3dB
= 1kHz, V
S
=
±5V,
T
A
= 25°C, f
CLK
= 100kHz, Ratio = 100:1
FREQUENCY(kHz)
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
1.200
GAIN (dB)
– 0.174
– 0.300
– 0.440
– 0.610
– 0.810
– 1.090
– 1.480
– 2.080
– 3.500
– 8.720
– 17.720
DELAY (ms)
0.842
0.861
0.888
0.933
0.999
1.095
1.242
1.503
1.832
1.724
1.183
U W
Table 4. Gain/Phase, Pin 10 at V
–
, Typical Response
f
–3dB
= 1kHz, V
S
=
±5V,
T
A
= 25°C, f
CLK
= 100kHz, Ratio = 100:1
FREQUENCY(kHz)
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1.800
2.000
GAIN (dB)
– 0.179
– 0.440
– 0.810
– 1.480
– 3.500
– 17.720
– 35.700
– 52.700
– 71.900
– 96.160
PHASE (deg)
–60.090
–122.000
170.800
91.900
–16.300
–140.500
164.800
135.000
114.000
–49.670
Table 6. Gain/Phase, Pin 10 at GND
V
S
=
±5V,
T
A
= 25°C
FREQUENCY(kHz)
0.200
0.400
0.600
0.800
1.000
1.200
1.400k
1.600
1.800
2.000
GAIN (dB)
– 0.383
– 1.000
– 1.300
– 0.280
2.670
– 3.500
– 12.510
– 20.000
– 27.300
– 35.000
PHASE (deg)
–47.140
–92.000
–134.300
–178.800
109.200
6.000
–47.400
–88.800
–127.800
–164.200
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