LINER LTC1164-6CN Low power 8th order pin selectable elliptic or linear phase lowpass filter Datasheet

LTC1164-6
Low Power 8th Order
Pin Selectable Elliptic or
Linear Phase Lowpass Filter
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DESCRIPTIO
FEATURES
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8th Order Pin Selectable Elliptic or Bessel Filter in a
14-Pin Package
4mA Supply Current with ±5V Supplies
64dB Attenuation at 1.44 fCUTOFF (Elliptic Response)
fCUTOFF up to 30kHz (50:1 fCLK to fCUTOFF Ratio)
110µVRMS Wideband Noise with ±5V Supplies
Operates at Single 5V Supply with 1VRMS
Input Range
Operates up to ±8V Supplies
TTL/CMOS Compatible Clock Input
No External Components
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APPLICATI
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Anti-Aliasing Filters
Battery-Operated Instruments
Telecommunication Filters
The LTC1164-6 provides an elliptic lowpass rolloff with
stopband attenuation of 64dB at 1.44 fCUTOFF and an fCLKto-fCUTOFF ratio of 100:1 (pin 10 to V –). For a ratio of 100:1,
fCUTOFF can be clock-tuned up to 10kHz. For a fCLK-tofCUTOFF ratio of 50:1 (pin 10 to V +), the LTC1164-6
provides an elliptic lowpass filter with fCUTOFF frequencies
up to 20kHz. When pin 10 is connected to ground, the
LTC1164-6 approximates an 8th order linear phase response with 65dB attenuation at 4.5 f – 3dB and fCLK / f – 3dB
ratio of 160:1. The LTC1164-6 is pin compatible with the
LTC1064-1.
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The LTC1164-6 is a monolithic 8th order elliptic lowpass
filter featuring clock-tunable cutoff frequency and low
power supply current. Low power operation is achieved
without compromising noise or distortion performance.
At ±5V supplies the LTC1164-6 uses only 4mA supply
current while keeping wideband noise below 110µVRMS.
With a single 5V supply, the LTC1164-6 can provide up to
10kHz cutoff frequency and 80dB signal-to-noise ratio
while consuming only 2.5mA.
TYPICAL APPLICATI
10kHz Anti-Aliasing Elliptic Filter
VIN
1
14
2
13
3
8V
4
12
LTC1164-6
11
5
10
6
9
7
8
0
NC
–10
–8V
–20
CLK = 1MHz
–8V
VOUT
GAIN (dB)
NC
Frequency Response
–30
–40
–50
–60
1164-6 TA01
–70
WIDEBAND NOISE = 115µVRMS
NOTE: THE CONNECTION FROM PIN 7 TO PIN 14 SHOULD BE MADE
UNDER THE PACKAGE. THE POWER SUPPLIES SHOULD BE BYPASSED
BY A 0.1µF CAPACITOR AS CLOSE TO THE PACKAGE AS POSSIBLE.
–80
1
10
FREQUENCY (kHz)
100
1164-6 TA02
1
LTC1164-6
W W
W
AXI U
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ABSOLUTE
RATI GS (Note 1)
Total Supply Voltage (V + to V –) ............................. 16V
Input Voltage (Note 2) ......... (V ++ 0.3V) to (V – – 0.3V)
Output Short-Circuit Duration ......................... Indefinite
Power Dissipation............................................. 400mW
Burn-In Voltage ...................................................... 16V
Operating Temperature Range
LTC1164-6C ...................................... – 40°C to 85°C
LTC1164-6M ................................... – 55°C to 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
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W
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
ORDER PART
NUMBER
TOP VIEW
NC
1
14 CONNECT 2
NC 1
16 CONNECT 2
VIN
2
13 NC
VIN 2
15 NC
3
V–
GND 3
14 V –
GND
12
V+
4
11 CLK
GND
5
10 ELL/BESS
LP6
6
9
CONNECT 1
7
J PACKAGE
14-LEAD CERAMIC DIP
8
VOUT
LTC1164-6CN
LTC1164-6CJ
LTC1164-6MJ
V+
GND 5
12 CLK
NC 6
11 ELL/BESS
LP6 7
NC
10 NC
CONNECT 1 8
N PACKAGE
14-LEAD PLASTIC DIP
LTC1164-6CS
13 NC
4
ORDER PART
NUMBER
9
VOUT
S PACKAGE
16-LEAD PLASTIC SOL
TJMAX = 150°C, θJA = 65°C/W (J)
TJMAX = 110°C, θJA = 65°C/W (N)
TJMAX = 110°C, θJA = 85°C/W
ELECTRICAL CHARACTERISTICS
VS = ±7.5V, RL = 10k, TA = 25°C, fCLK = 400kHz, TTL or CMOS level (maximum clock rise or fall time ≤ 1µs) and all gain
measurements are referenced to passband gain, unless otherwise specified. (fCLK /fCUTOFF) = 4kHz at 100:1 and 8kHz at 50:1.
PARAMETER
Passband Gain 0.1Hz to 0.25 fCUTOFF (Note 4)
Passband Ripple with VS = Single 5V
Gain at 0.50 fCUTOFF (Note 3)
Gain at 0.90 fCUTOFF (Note 3)
Gain at 0.95 fCUTOFF (Note 3)
Gain at fCUTOFF (Note 3)
Gain at 1.44 fCUTOFF (Note 3)
Gain at 2.0 fCUTOFF (Note 3)
Gain with fCLK = 20kHz
Gain with VS = ±2.375V
Input Frequency Range (Tables 3, 4)
Maximum fCLK (Table 3)
2
CONDITIONS
fIN = 1kHz, (fCLK / fC) = 100:1
1Hz to 0.8 fC (Table 2)
fIN = 2kHz, (fCLK / fC) = 100:1
fIN = 3.6kHz, (fCLK / fC) = 100:1
fIN = 3.8kHz, (fCLK / fC) = 100:1
fIN = 4kHz, (fCLK / fC) = 100:1
fIN = 8kHz, (fCLK / fC) = 50:1
fIN = 5.76kHz, (fCLK / fC) = 100:1
fIN = 8kHz, (fCLK / fC) = 100:1
fIN = 200Hz, (fCLK / fC) = 100:1
fIN = 400kHz, fIN = 2kHz, (fCLK / fC) = 100:1
fIN = 400kHz, fIN = 4kHz, (fCLK / fC) = 100:1
(fCLK / fC) = 100:1
(fCLK / fC) = 50:1
VS ≥ ±7.5V
VS ≤ ±5V
VS = Single 5V, AGND = 2V
●
●
●
●
●
●
●
●
MIN
– 0.50
– 0.45
– 0.75
–1.40
– 3.50
– 3.00
–69
– 69
– 3.50
– 0.50
– 3.30
TYP
– 0.15
0.1 to – 0.3
– 0.10
– 0.30
– 0.70
– 2.70
– 2.10
– 64
– 64
– 2.70
– 0.10
– 2.50
0 – <fCLK/2
0 – <fCLK
1.5
1.0
1.0
MAX
0.25
0.10
0.10
– 0.40
– 2.30
– 1.50
– 58
– 58
– 2.30
0.30
– 2.00
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
kHz
kHz
MHz
MHz
MHz
LTC1164-6
ELECTRICAL CHARACTERISTICS
VS = ±7.5V, RL = 10k, TA = 25°C, fCLK = 400kHz, TTL or CMOS level (maximum clock rise or fall time ≤ 1µs) and all gain
measurements are referenced to passband gain, unless otherwise specified. (fCLK / fCUTOFF) = 4kHz at 100:1 and 8kHz at 50:1.
PARAMETER
Clock Feedthrough
CONDITIONS
Input at GND, f = fCLK, Square Wave
VS = ±7.5V, (fCLK / fC) = 100:1
VS = ±5V, (fCLK / fC) = 50:1
Input at GND, 1Hz ≤ f < fCLK
VS = ±7.5V
VS = ±2.5V
Wideband Noise
Input Impedance
Output DC Voltage Swing
MIN
VS = ±2.375V
VS = ±5V
VS = ±7.5V
VS = ±5V, (fCLK / fC) = 100:1
VS = ±5V, (fCLK / fC) = 100:1
VS = ±2.375V, TA > 25°C
Output DC Offset
Output DC Offset TempCo
Power Supply Current
●
●
●
TYP
30
±1.25
±3.70
±5.40
MAX
500
200
µVRMS
µVRMS
115 ± 5%
100 ± 5%
40
±1.50
±4.10
±5.90
±100
±100
2.5
µVRMS
µVRMS
kΩ
V
V
V
mV
µV/°C
mA
mA
mA
mA
mA
mA
V
●
VS = ±5V, TA > 25°C
4.5
●
VS = ±7.5V, TA > 25°C
7.0
●
±2.375
Power Supply Range
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which life of
the device may be impaired.
Note 2: Connecting any pin to voltages greater than V + or less than V –
UNITS
70
±160
4.0
4.5
7.0
8.0
11.0
12.5
±8
may cause latch-up. It is recommended that no sources operating from
external supplies be applied prior to power-up of the LTC1164-6.
Note 3: All gains are measured relative to passband gain.
Note 4: The cutoff frequency of the filter is abbreviated as fCUTOFF or fC.
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TYPICAL PERFOR A CE CHARACTERISTICS
Stopband Gain vs Frequency
(Elliptic Response)
Stopband Gain vs Frequency
(Elliptic Response)
10
10
0
–10
GAIN (dB)
–20
–30
–40
–50
–10
–20
–30
–40
–50
–60
–60
–70
–70
–80
–80
–90
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1164-6 G01
VS = ±5V
fCLK = 250kHz
(fCLK /fC) = 50:1
(PIN 10 AT V +)
TA = 25°C
WITH EXTERNAL
SINGLE POLE LOWPASS RC FILTER
(f – 3dB = 10kHz)
0
GAIN (dB)
VS = ±5V
fCLK = 500kHz
fC = 5kHz
(fCLK /fC) = 100:1
(PIN 10 AT V – )
TA = 25°C
–90
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1164-6 G02
3
LTC1164-6
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TYPICAL PERFOR A CE CHARACTERISTICS
Stopband Gain vs Frequency
(Linear Phase Response)
Passband Gain and Phase
vs Frequency
10
GAIN (dB)
–20
–30
GAIN (dB)
–10
–40
–50
–60
0
1.5
–45
1.0
–90
0.5
–135
0
–180
–0.5
–225
–1.0
–2.0
B
–80
–270
VS = ±5V
fCLK = 500kHz
fC = 5kHz
(fCLK /fC) = 100:1
(PIN 10 AT V – )
TA = 25°C
–1.5
A
–70
–90
2.0
–2.5
–315
–360
–405
–450
–3.0
2
6
10 14 18 22 26 30 34 38 42
FREQUENCY (kHz)
4
2
3
FREQUENCY (kHz)
1
5
1164-6 G03
0.4
0
3
0
0.4
2
–30
0.2
1
–60
0
–90
–0.2
PHASE
0
GAIN (dB)
–0.8
VS = ±5V
fCLK = 500kHz
fC = 5kHz
(fCLK /fC) = 100:1
(PIN 10 AT V – )
TA = 25°C
(10 REPRESENTATIVE UNITS)
–1.6
–2.0
–2.4
–2.8
–1
–120
GAIN
–2
–3
–4
–5
–6
–150
–180
VS = ±5V
fCLK = 800kHz
fC = 5kHz
(fCLK /fC) = 160:1
(PIN 10 AT GND)
TA = 25°C
–7
0.4
1.0
2.2
2.8
1.6
FREQUENCY (kHz)
3.4
4.0
1
4
2
3
FREQUENCY (kHz)
0
– 0.5
–1.0
–1.5
D
–1.2
–270
–1.4
–300
–1.6
5
FREQUENCY (kHz)
1
1
5
INPUT FREQUENCY (kHz)
10
1164-6 G07
0
–45
–90
A
–135
0
B
–1
PHASE
–2
–3
–4
–7
–8
–180
A
–225
–270
B
–315
VS = ±5V
fCLK = 250kHz
fC = 5kHz
(fCLK /fC) = 50:1
(PIN 10 AT V – )
TA = 25°C
–360
–405
–450
–495
–540
–9
10
1164-6 G06
4
–240
VS = ±5V
fCLK = 1MHz
fC = 10kHz
(fCLK /fC) = 100:1
(PIN 10 AT V – )
2
–6
–2.0
– 3.0
–1.0
3
–5
C
–0.8
–210
1
GAIN (dB)
GAIN (dB)
0.5
B
–0.6
1
2
3
4
FREQUENCY (kHz)
5
1164-6 G08
PHASE (DEG)
A. fCLK = 400kHz
f CUTOFF = 4kHz
B. fCLK = 600kHz
f CUTOFF = 6kHz
C. fCLK = 800kHz
f CUTOFF = 8kHz
D. fCLK = 1MHz
f CUTOFF = 10kHz
VS = ±5V
(fCLK /fC) = 100:1
(PIN 10 AT V – )
TA = 25°C
A
A.T A = 125°C
B.T A = 85°C
D.T A = –40°C
Passband Gain and Phase vs
Frequency and fCLK
2.0
–2.5
B
C
1164-6 G11
Passband vs Frequency and fCLK
1.0
A
–0.4
5
1164-6 G05
1.5
PHASE (DEG)
–0.4
–1.2
Maximum Passband over
Temperature
GAIN (dB)
0.8
GAIN (dB)
1164-6 G04
Passband Gain and Phase vs
Frequency (Linear Phase Response)
Passband Gain vs Frequency
PHASE (DEG)
A.RESPONSE WITHOUT
EXTERNAL RC FILTER
B.RESPONSE WITH AN
EXTERNAL SINGLE
POLE LOWPASS RC
FILTER (f – 3dB AT 10kHz)
VS = ±5V
fCLK = 800kHz
fC = 5kHz
(fCLK /fC) = 160:1
(PIN 10 AT GND)
TA = 25°C
0
A.RESPONSE WITHOUT
EXTERNAL SINGLE
POLE RC FILTER
B.RESPONSE WITH AN
EXTERNAL SINGLE
POLE LOWPASS RC
FILTER (f – 3dB AT 10kHz)
LTC1164-6
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TYPICAL PERFOR A CE CHARACTERISTICS
Maximum Passband over
Temperature
Passband vs Frequency and fCLK
2.0
1.0
0
–0.5
A
B
–1.0
–1.5
1.5
1.0
C
–2.5
1
0
TA = –40°C
–0.5
–1.0
VS = SINGLE 5V
(fCLK /fC) = 50:1
GND = 2V WITH
EXTERNAL RC
LOWPASS FILTER
(f – 3dB = 40kHz)
–1.5
VS = ±8V
(fCLK /f C) = 50:1
(PIN 10 AT V +)
TA = 25°C
–2.0
TA = 70°C
0.5
GAIN (dB)
GAIN (dB)
0.5
–3.0
2.0
A. fCLK = 250kHz
f CUTOFF = 5kHz
B. fCLK = 500kHz
f CUTOFF = 10kHz
C. fCLK = 1MHz
f CUTOFF = 20kHz
1.5
–2.0
–2.5
10
FREQUENCY (kHz)
–3.0
30
2
4
6
8 10 12 14 16 18 20 22
FREQUENCY (kHz)
1164-6 G09
Group Delay vs Frequency
(Linear Phase Response)
Group Delay vs Frequency
(Elliptic Response)
– 40
A.f CLK = 250kHz, (fCLK /fC) = 50:1
WITH EXTERNAL RC LOWPASS
FILTER (f C = 10kHz)
B.f CLK = 500kHz
(f CLK /fC) = 100:1
GROUP DELAY (µs)
600
150
100
500
400
300
200
2
3
4 5 6 7 8
FREQUENCY (kHz)
9
2
4
3
FREQUENCY (kHz)
1
5
THD + NOISE (dB)
– 50
–70
–75
–55
–40
VS = SINGLE 5V, VIN = 0.7VRMS
fCLK = 500kHz, fC = 5kHz,
(fCLK /fC) = 100:1, TA = 25°C
(5 REPRESENTATIVE UNITS)
–50
–60
–65
–70
–75
–55
–60
–65
–70
–75
–80
–80
–85
–85
–85
–90
–90
0.5
5
FREQUENCY (kHz)
10
–90
1
5
FREQUENCY (kHz)
1164-6 G14
VS = ±5V
VIN = 1VRMS
fCLK = 800kHz
fC = 5kHz
(fCLK /fC) = 160:1
TA = 25°C
–45
–80
1
5
4
THD + Noise vs Frequency
(Linear Phase Response)
THD + NOISE (dB)
–45
–65
2
3
FREQUENCY (kHz)
1164-6 G13
– 40
VS = ±5V, VIN = 1VRMS,
fCLK = 500kHz, fC = 10kHz,
(fCLK /fC) = 50:1, TA = 25°C,
WITH EXTERNAL RC LOWPASS
FILTER (f – 3dB = 20kHz)
(5 REPRESENTATIVE UNITS)
–60
–75
THD + Noise vs Frequency
(Elliptic Response)
– 40
–55
–70
1164-6 G12
THD + Noise vs Frequency
(Elliptic Response)
– 50
–65
–90
1
10 11
1164-6 G22
–45
–60
–85
0
1
–55
–80
VS = ±5V
fC = 5kHz
TA = 25°C
100
0
– 50
A
B
50
VS = ±5V, VIN = 1VRMS
(20k RESISTOR PIN 14 TO V – )
fCLK = 500kHz, fC = 5kHz
(fCLK /fC) = 100:1, TA = 25°C
(5 REPRESENTATIVE UNITS)
–45
THD + NOISE (dB)
fCLK = 800kHz
(fCLK /fC) = 160:1
fC = 5kHz
200
THD + NOISE (dB)
THD + Noise vs Frequency
(Elliptic Response)
700
250
GROUP DELAY (µs)
1164-6 G10
1164-6 G16
1
2
3
FREQUENCY (kHz)
5
4
1164-6 G23
5
LTC1164-6
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TYPICAL PERFOR A CE CHARACTERISTICS
THD + Noise vs RMS Input
(Elliptic Response)
– 40
–40
–45
– 50
–50
–55
–55
–60
VS = ±5V
–65
–70
–75
–80
11
A
–65
–70
–75
–85
–90
0.1
–90
0.1
5
25°C
7
125°C
6
5
4
2
A. GND = 2.5V
B. GND = 2V
1
0
1
2
0
INPUT (VRMS)
1164-6 G17
1
2 3 4
5 6 7 8
POWER SUPPLY (V + OR V –)
1164-6 G18
Transient Response
9
10
1164-6 G19
2V/DIV
2V/DIV
Transient Response
1ms/DIV
U
U
U
PI FU CTIO S
1164-6 G21
VS = ±7.5V, VIN = ±3V 100Hz SQUARE WAVE
fCLK = 800kHz, (fCLK /f C) = 160:1, fCUTOFF = 5kHz
LINEAR PHASE RESPONSE
(14-Lead Dual-In-Line Package)
Power Supply Pins (4, 12)
–
1ms/DIV
1164-6 G20
VS = ±7.5V, VIN = ±3V 100Hz SQUARE WAVE
fCLK = 500kHz, (fCLK /f C) = 100:1, fCUTOFF = 5kHz
ELLIPTIC RESPONSE
The V (pin 4) and the V (pin 12) should be bypassed with
a 0.1µF capacitor to an adequate analog ground. The
filter’s power supplies should be isolated from other
digital or high voltage analog supplies. A low noise linear
supply is recommended. Using a switching power supply
will lower the signal-to-noise ratio of the filter. The supply
during power-up should have a slew rate less than 1V/µs.
When V + is applied before V – and V – could go above
ground, a signal diode must be used to clamp V –. Figures
6
8
3
INPUT (VRMS)
+
9
B
–60
–85
–55°C
10
–80
VS = ±7.5V
1
12
(fCLK /fC) = 100:1 OR 50:1
fIN = 1kHz, TA = 25°C
CURRENT (mA)
(fCLK /fC) = 100:1 OR 50:1
fIN = 1kHz, TA = 25°C
THD + NOISE (dB)
THD + NOISE (dB)
–45
Power Supply Current vs Power
Supply Voltage
THD + Noise vs RMS Input for
Single 5V (Elliptic Response)
1 and 2 show typical connections for dual and single
supply operation.
Clock Input Pin (11)
Any TTL or CMOS clock source with a square-wave output
and 50% duty cycle (±10%) is an adequate clock source
for the device. The power supply for the clock source
should not be the filter’s power supply. The analog ground
for the filter should be connected to clock’s ground at a
single point only. Table 1 shows the clock’s low and high
LTC1164-6
U
U
U
PI FU CTIO S
(14-Lead Dual-In-Line Package)
level threshold value for a dual or single supply operation.
A pulse generator can be used as a clock source provided
the high level ON time is greater than 0.5µs. Sine waves are
not recommended for clock input frequencies less than
100kHz, since excessively slow clock rise or fall times
generate internal clock jitter (maximum clock rise or fall
time ≤ 1µs). The clock signal should be routed from the
right side of the IC package to avoid coupling into any input
or output analog signal path. A 1k resistor between clock
source and pin 11 will slow down the rise and fall times of
the clock to further reduce charge coupling, Figures 1
and 2.
V–
VIN
1
14
2
13
3
12
4
V+
0.1µF
LTC1164-6
0.1µF
1k
11
5
10
6
9
7
*
CLOCK SOURCE
* OPTIONAL
VOUT
1164-6 F01
Figure 1. Dual Supply Operation for fCLK/fCUTOFF = 100:1
1
14
2
13
3
12
4
V+
0.1µF
10k
10k
LTC1164-6
The filter performance depends on the quality of the
analog signal ground. For either dual or single supply
operation, an analog ground plane surrounding the package is recommended. The analog ground plane should be
connected to any digital ground at a single point. For dual
supply operation, pins 3 and 5 should be connected to the
analog ground plane. For single supply operation pins 3
and 5 should be biased at 1/2 supply and they should be
bypassed to the analog ground plane with at least a 1µF
capacitor (Figure 2). For single 5V operation at the highest
fCLK of 1MHz, pins 3 and 5 should be biased at 2V. This
minimizes passband gain and phase variations (see Typical Performance Characteristics curves: Maximum Passband for Single 5V, 50:1; and THD + Noise vs RMS Input
for Single 5V, 50:1).
Elliptic/Linear Phase Select Pin (10)
+
GND
DIGITAL SUPPLY
8
VIN
Analog Ground Pins (3, 5)
11
5
10
6
9
7
8
1k
CLOCK SOURCE
+
GND
DIGITAL SUPPLY
+
The DC level at this pin selects the desired filter response,
elliptic or linear phase and determines the ratio of the clock
frequency to the cutoff frequency of the filter. Pin 10
connected to V – provides an elliptic lowpass filter with
clock-to-fCUTOFF ratio of 100:1. Pin 10 connected to
analog ground provides a linear phase lowpass filter with
a clock- to-f –3dB ratio of 160:1 and a transient response
overshoot of 1%. When pin 10 is connected to V + the
clock-to-fCUTOFF ratio is 50:1 and the filter response is
elliptic. Bypassing pin 10 to analog ground reduces the
output DC offsets. If the DC level at pin 10 is switched
mechanically or electrically at slew rates greater than 1V/
µs while the device is operating, a 10k resistor should be
connected between pin 10 and the DC source.
1µF
Filter Input Pin (2)
VOUT
1164-6 F02
Figure 2. Single Supply Operation for fCLK/fCUTOFF = 100:1
The input pin is connected internally through a 50k resistor tied to the inverting input of an op amp.
Table 1. Clock Source High and Low Threshold Levels
Filter Output Pins (9, 6)
POWER SUPPLY
Dual Supply = ±7.5V
Dual Supply = ±5V
Dual Supply = ±2.5V
Single Supply = 12V
Single Supply = 5V
Pin 9 is the specified output of the filter; it can typically
source or sink 1mA. Driving coaxial cables or resistive
loads less than 20k will degrade the total harmonic distortion of the filter. When evaluating the device’s distortion an
output buffer is required. A noninverting buffer, Figure 3,
HIGH LEVEL
≥ 2.18V
≥ 1.45V
≥ 0.73V
≥ 7.80V
≥ 1.45V
LOW LEVEL
≤ 0.5V
≤ 0.5V
≤ – 2.0V
≤ 6.5V
≤ 0.5V
7
LTC1164-6
U
U
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PI FU CTIO S (14-Lead Dual-In-Line Package)
can be used provided that its input common-mode range
is well within the filter’s output swing. Pin 6 is an intermediate filter output providing an unspecified 6th order
lowpass filter. Pin 6 should not be loaded.
–
1k
External Connection Pins (7, 14)
Pins 7 and 14 should be connected together. In a printed
circuit board the connection should be done under the IC
package through a short trace surrounded by the analog
ground plane.
NC Pin (1, 8, 13)
+
Pins 1, 8, and 13 are not connected to any internal circuit
point on the device and should preferably be tied to analog
ground.
LT1006, fC < 5kHz
LT1200, fC > 5kHz
1164-6 F03
Figure 3. Buffer for Filter Output
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APPLICATI
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Passband Response
The passband response of the LTC1164-6 is optimized for
a fCLK/fCUTOFF ratio of 100:1. Minimum passband ripple
occurs from 1Hz to 80% of fCUTOFF. Athough the passband
of the LTC1164-6 is optimized for ratio fCLK / fCUTOFF of
100:1, if a ratio of 50:1 is desired, connect a single pole
lowpass RC (f –3dB = 2 fCUTOFF) at the output of the filter.
The RC will make the passband gain response as flat as the
100:1 case. If the RC is omitted, and clock frequencies are
below 500kHz the passband gain will peak by 0.4dB at
90% fCUTOFF.
Table 2. Typical Passband Ripple with Single 5V Supply
(fCLK/fC) = 100:1, GND = 2V, 30kHz, Fixed Single Pole, Lowpass
RC Filter at Pin 9 (See Typical Applications)
PASSBAND
FREQUENCY
% of fCUTOFF
10
20
30
40
50
60
70
80
90
fCUTOFF
8
PASSBAND GAIN
(REFERENCED TO 0dB)
fCUTOFF = 1kHz
fCUTOFF = 10kHz
TA = 0°C
TA = 25°C
TA = 70°C
TA = 25°C
(dB)
(dB)
(dB)
(dB)
0.00
0.00
0.00
0.00
– 0.02
0.00
0.01
0.01
– 0.05
– 0.01
– 0.01
0.01
– 0.10
– 0.02
– 0.02
0.02
– 0.13
– 0.03
– 0.01
0.03
– 0.15
– 0.01
0.01
0.05
– 0.18
– 0.01
0.01
0.07
– 0.25
– 0.08
– 0.05
0.02
– 0.39
– 0.23
– 0.18
– 0.05
– 2.68
– 2.79
– 2.74
– 2.68
The gain peaking can approximate a sin χ/χ correction for
some applications. (See Typical Performance Characteristics curve, Passband vs Frequency and fCLK at fCLK / fC =
50:1.)
When the LTC1164-6 operates with a single 5V supply and
its cutoff frequency is clock-tuned to 10kHz, an output
single pole RC filter can also help maintain outstanding
passband flatness from 0°C to 70°C. Table 2 shows
details.
Clock Feedthrough
Clock feedthrough is defined as, the RMS value of the clock
frequency and its harmonics that are present at the filter’s
output pin (9). The clock feedthrough is tested with the
input pin (2) grounded and, it depends on PC board layout
and on the value of the power supplies. With proper layout
techniques the values of the clock feedthrough are shown
in Table 3.
Table 3. Clock Feedthrough
VS
±2.5V
±5V
±7.5V
50:1
60µVRMS
100µVRMS
150µVRMS
100:1
60µVRMS
200µVRMS
500µVRMS
Note: The clock feedthrough at ±2.5V supplies is imbedded in the wideband
noise of the filter. (The clock signal is a square wave.)
LTC1164-6
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APPLICATI
S I FOR ATIO
Any parasitic switching transients during the rise and fall
edges of the incoming clock are not part of the clock
feedthrough specifications. Switching transients have frequency contents much higher than the applied clock; their
amplitude strongly depends on scope probing techniques
as well as grounding and power supply bypassing. The
clock feedthrough, if bothersome, can be greatly reduced
by adding a simple R/C lowpass network at the output of
the filter pin (9). This R/C will completely eliminate any
switching transient.
Table 4. Maximum VIN vs VS and fCLK
Wideband Noise
INPUT FREQUENCY
OUTPUT LEVEL
(Relative to Input)
(VIN = 1VRMS)
(kHz)
(dB)
fCLK/fC = 100:1, fCUTOFF = 1kHz
The wideband noise of the filter is the total RMS value of
the device’s noise spectral density and it is used to
determine the operating signal-to-noise ratio. Most of its
frequency contents lie within the filter passband and it
cannot be reduced with post filtering. For instance, the
LTC1164-6 wideband noise at ±2.5V supply is 100µVRMS,
90µVRMS of which have frequency contents from DC up to
the filter’s cutoff frequency. The total wideband noise
(µVRMS) is nearly independent of the value of the clock.
The clock feedthrough specifications are not part of the
wideband noise.
Speed Limitations
The LTC1164-6 optimizes AC performance versus power
consumption. To avoid op amp slew rate limiting at
maximum clock frequencies, the signal amplitude should
be kept below a specified level as shown on Table 4.
Aliasing
Aliasing is an inherent phenomenon of sampled data
systems and it occurs when input frequencies close to the
sampling frequency are applied. For the LTC1164-6 case,
an input signal whose frequency is in the range of fCLK
±4%, will be aliased back into the filter’s passband. If, for
instance, an LTC1164-6 operating with a 100kHz clock
and 1kHz cutoff frequency receives a 98.5kHz, 10mVRMS
input signal, a 1.5kHz, 10µVRMS alias signal will appear at
its output. When the LTC1164-6 operates with a clock-tocutoff frequency of 50:1, aliasing occurs at twice the clock
frequency. Table 5 shows details.
POWER SUPPLY
±7.5V
±5V
Single 5V
MAXIMUM fCLK
1.5MHz
1MHz
≥1MHz
1MHz
1MHz
1MHz
1MHz
MAXIMUM VIN
1VRMS (fIN > 35kHz)
3VRMS (fIN > 25kHz)
0.7VRMS (fIN > 250kHz)
2.5VRMS (fIN > 25kHz)
0.5VRMS (fIN > 100kHz)
0.7VRMS (fIN > 25kHz)
0.5VRMS (fIN > 100kHz)
Table 5. Aliasing (fCLK = 100kHz)
96 (or 104)
97 (or 103)
98 (or 102)
98.5 (or 101.5)
99 (or 101)
99.5 (or 100.5)
fCLK/fC = 50:1, fCUTOFF = 2kHz
192 (or 208)
194 (or 206)
196 (or 204)
198 (or 202)
199 (or 201)
199.5(or 200.5)
OUTPUT FREQUENCY
(Aliased Frequency)
(kHz)
–75.0
– 68.0
– 65.0
– 60.0
– 3.2
– 0.5
4.0
3.0
2.0
1.5
1.0
0.5
– 76.0
– 68.0
– 63.0
– 3.4
– 1.3
– 0.9
8.0
6.0
4.0
2.0
1.0
0.5
Table 6. Transient Response of LTC Lowpass Filters
LOWPASS FILTER
DELAY
TIME*
(SEC)
RISE
TIME**
(SEC)
SETTLING OVERTIME*** SHOOT
(SEC)
(%)
LTC1064-3 Bessel
0.50/fC
0.34/fC
0.80/fC
0.5
LTC1164-5 Linear Phase
0.43/fC
0.34/fC
0.85/fC
0
LTC1164-6 Linear Phase
0.43/fC
0.34/fC
1.15/fC
1
LTC1264-7 Linear Phase
1.15/fC
0.36/fC
2.05/fC
5
LTC1164-7 Linear Phase
1.20/fC
0.39/fC
2.20/fC
5
LTC1064-7 Linear Phase
1.20/fC
0.39/fC
2.20/fC
5
LTC1164-5 Butterworth
0.80/fC
0.48/fC
2.40/fC
11
LTC1164-6 Elliptic
0.85/fC
0.54/fC
4.30/fC
18
LTC1064-4 Elliptic
0.90/fC
0.54/fC
4.50/fC
20
LTC1064-1 Elliptic
0.85/fC
0.54/fC
6.50/fC
20
* To 50% ±5%, ** 10% to 90% ±5%, *** To 1% ±0.5%
9
LTC1164-6
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TYPICAL APPLICATI
S
8th Order Elliptic Lowpass Filter
(fCLK / fC) = 50:1
VIN
1
14
2
13
3
12
4
V+
0.1µF
LTC1164-6
11
5
10
6
9
7
8
V+
NOTES:
1. OPTIONAL OUTPUT BUFFER
1/2πRC = 2 × fCUTOFF.
2. PINS 1, 8, 13 CAN BE GROUNDED
OR LEFT FLOATING.
V–
–
0.1µF
fCLK
V+
LT1006
R
+
VOUT
1164-6 TA06
C
V–
8th Order Elliptic Lowpass Filter
(fCLK / fC) = 100:1
VIN
V
1
14
1
14
2
13
2
13
3
12
3
12
4
+
0.1µF
8th Order Linear Phase Lowpass Filter
(fCLK / fC) = 160:1
LTC1164-6
VIN
V–
11
5
10
6
9
7
8
fCLK
4
V+
0.1µF
0.1µF
VOUT
LTC1164-6
11
5
10
6
9
7
8
V–
fCLK
0.1µF
VOUT
1164-6 TA07
1164-6 TA08
8th Order 20kHz Cutoff, Elliptic Filter Operating
with a Single 5V Supply and Driving 1k, 1000pF Load
VIN
1
14
2
13
3
12
4
5V
0.1µF
10k
LTC1164-6
11
5
10
6
9
7
8
5V
1k
5V
fCLK
= 1MHz
5V
51.1k
2
–
7
VOUT
LT1200
10k
3
+
4
1k
1000pF
NOTES:
1. TOTAL SUPPLY CURRENT IS = 4mA
(EXCLUDING OUTPUT LOAD CURRENT).
2. FLAT PASSBAND UP TO 18kHz,
f –3dB = 20kHz.
3. THD + NOISE ≤ –70dB,
1VP-P ≤ VIN ≤ 3VP-P, fIN = 1kHz.
510pF
1164-6 TA09
0.1µF
10
6.65k
LTC1164-6
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TYPICAL APPLICATI
S
8th Order Low Power, Clock-Tunable Elliptic Filter with
Active RC Input Anti-Aliasing Filter and Output Smoothing Filter
C2
0.022µF
R1
1.15k
R2
76.8k
R3
5.62k
VIN
C3
0.001µF
C1
0.1µF
+
1
14
1/2
LT1013
2
13
3
12
4
11
–
V
fC = 1kHz
ATTENUATION AT 10kHz = –48dB
+
0.1µF
NOTES:
1. CLOCK-TUNABLE OVER ONE DECADE
OF CUTOFF FREQUENCY.
2. BOTH INPUT AND OUTPUT RC ACTIVE
FILTERS ARE 0.1dB CHEBYSHEV FILTERS
WITH 1kHz RIPPLE BANDWIDTH.
10
6
9
7
8
fCLK
–
1/2
LT1013
V–
R1
16.9k
R2
97.6k
100Hz ≤ fC ≤ 1kHz
10kHz ≤ fCLK ≤ 100kHz
C2
0.001µF
VOUT
+
C1
0.0047µF
fC = 1kHz
ATTENUATION AT 10kHz = –30dB
1164-6 TA10
Single 5V, 16th Order Lowpass Filter
fCUTOFF = 10kHz
R1
789Ω
VIN
LTC1164-6
5
V–
0.1µF
C1
0.01µF
1
14
1
14
2
13
2
13
12
3
11
4
3
4
5V
0.1µF
5
15k
+
1µF
LTC1164-6
IC1
5V
10
5V
5
0.1µF
12
LTC1164-6
IC2
11
10
6
9
6
9
7
8
7
8
10k
fCLK
5V
VOUT
C2
0.001µF
R2
7.89k
1k
1164-6 TA03
VS = SINGLE 5V, IS = 5mA TYP
16TH ORDER LOWPASS FILTER
FIXED fCUTOFF, fCLK = 540kHz
fCUTOFF = 10kHz
(fCLK/fC) = 54:1
1/2πR1C1 = 1/2πR2C2 = 2fCUTOFF
THD + Noise vs Frequency
–40
0
–45
–10
–50
–20
–55
THD + NOISE (dB)
GAIN (dB)
Gain vs Frequency
10
–30
–40
–50
VS = SINGLE 5V
IS = 5mA, 16TH ORDER
ELLIPTIC LOWPASS
fCLK = 540kHz
fCUTOFF = 10kHz
–60
–70
–80
VS = SINGLE 5V
IS = 5mA, 16TH ORDER
ELLIPTIC LOWPASS
VIN = 0.5VRMS
fCLK = 540kHz
fC = 10kHz
–60
–65
–70
–75
–80
–85
–90
–90
1
10
FREQUENCY (kHz)
30
1
5
FREQUENCY (kHz)
1164-6 TA04
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
10
1164-6 TA05
11
LTC1164-6
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PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
J Package
14-Lead Ceramic DIP
0.200
(5.080)
MAX
0.290 – 0.320
(7.366 – 8.128)
0.785
(19.939)
MAX
0.005
(0.127)
MIN
14
12
13
11
10
9
8
0.015 – 0.060
(0.381 – 1.524)
0.008 – 0.018
(0.203 – 0.460)
0.220 – 0.310
(5.588 – 7.874)
0.025
(0.635)
RAD TYP
0° – 15°
1
0.385 ± 0.025
(9.779 ± 0.635)
0.038 – 0.068
(0.965 – 1.727)
0.100 ± 0.010
(2.540 ± 0.254)
0.014 – 0.026
(0.360 – 0.660)
2
3
4
5
6
7
0.098
(2.489)
MAX
0.125
(3.175)
MIN
J14 0392
N Package
14-Lead Plastic DIP
0.300 – 0.325
(7.620 – 8.255)
0.045 – 0.065
(1.143 – 1.651)
0.015
(0.380)
MIN 0.130 ± 0.005
(3.302 ± 0.127)
(
+0.635
8.255
–0.381
)
14
13
12
11
10
9
8
1
2
3
4
5
6
7
0.260 ± 0.010
(6.604 ± 0.254)
0.009 – 0.015
(0.229 – 0.381)
+0.025
0.325 –0.015
0.770
(19.558)
MAX
0.065
(1.651)
TYP
0.075 ± 0.015
(1.905 ± 0.381)
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
0.125
(3.175)
MIN
S Package
16-Lead Plastic SOL
0.398 – 0.413
(10.109 – 10.490)
0.291 – 0.299
(7.391 – 7.595)
0.005
(0.127)
RAD MIN
0.010 – 0.029 × 45°
(0.254 – 0.737)
16
0.093 – 0.104
(2.362 – 2.642)
15
14
13
12
11
10
9
0.037 – 0.045
(0.940 – 1.143)
0° – 8° TYP
0.394 – 0.419
(10.007 – 10.643)
SEE NOTE
0.009 – 0.013
(0.229 – 0.330)
SEE NOTE
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
TYP
0.004 – 0.012
(0.102 – 0.305)
0.014 – 0.019
(0.356 – 0.482)
TYP
NOTE:
PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS.
1
2
3
4
5
6
7
8
SOL16 0392
12
Linear Technology Corporation
LT/GP 0293 10K REV 0
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1993
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