LTC1164-8CSW Linear Technology, LTC1164-8CSW Datasheet - Page 7

• Manufacturer Part Number: LTC1164-8CSW
• Description: IC FILTR 8TH ORDR LOWPASS 16SOIC
• Manufacturer: Linear Technology

Specifications of LTC1164-8CSW

• Filter Type: Elliptic Bandpass Switched Capacitor
• Frequency - Cutoff Or Center: 7kHz
• Number Of Filters: 1
• Max-order: 8th
• Voltage - Supply: 4.75 V ~ 16 V, ±2.375 V ~ 8 V
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC1164-8CS

APPLICATIONS
Passband Gain and Dynamic Range
The filter’s gain at f
and resistors R
frequency (f
by 100. The output dynamic range of LTC1164-8 is opti-
mized for minimum noise and maximum voltage swing
when resistor R
depends on the filter’s gain and it is calculated by the
equation R
and R
with resistor R
the filter . Table 3 shows the noise generated by the filter
with its input grounded.
Table 2. Passband Gain at Center Frequency, R
Table 3. LTC1164-8 Noise with Its Input Grounded
The passband of the LTC1164-8 is from 0.995 • f
1.005 • f
filter gain is – 3dB ±2dB relative to the gain at f
Figure 3 shows typical passband gain variations versus
percent of frequency deviation from f
filter’s passband, signal attenuation increases to – 50dB
for frequencies less than 0.96 • f
1.04 • f
In applications where a signal is to be detected in the
presence of wideband noise, the ultraselectivity of the
LTC1164-8 can improve the output signal-to-noise ratio.
When wideband noise (white noise) appears at the input to
GAIN
1000
100
200
500
10
20
50
1
2
5
POWER SUPPLY
F
for some typical gains. Increasing the filter’s gain
CENTER
R
Single 5V
CENTER
IN
68.1k
16.9k
6.81k
1.69k
680Ω
340Ω
340k
169k
3.4k
34k
±5V
(±1%)
IN
CENTER
= 340k/Gain. Table 2 lists the values of R
.
IN
. At the passband’s end points the typical
IN
does not increase the noise generated by
F
R
) is equal to the clock frequency divided
and R
F
U
CENTER
is 61.9k. The value of resistor R
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
(±1%)
INFORMATION
F
U
is set with an external op amp
(Figure 1). The filter’s center
GAIN IN dB R
10
15
20
25
30
35
40
45
50
0
CENTER
NOISE (μV
W
360 ±10%
270 ±10%
CENTER
IN
60.4k
19.1k
10.7k
6.01k
1.91k
1.07k
and greater than
340k
107k
3.4k
34k
IN
(±1%)
RMS
and R
. Outside the
)
U
CENTER
F
R
CENTER
F
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
61.9k
(±1%)
to
IN
IN
.
the filter, only a small amount of input noise will reach the
filter’s output. If the output noise of the LTC1164-8 is
neglected, the signal-to-noise ratio at the output of the
filter divided by the signal-to-noise ratio at the input of the
filter equals:
where,
(BW)
(BW)
Example: A small 1kHz signal is sent through a cable that
also conducts random noise. The cable bandwidth is
3.4kHz. An LTC1164-8 is used to detect the 1kHz signal.
The signal-to-noise ratio at the output of the filter is 25.3dB
larger than the signal-to-noise ratio at the input of the filter
(20 • Log√(BW)
1kHz = 25.3dB).
The AC output swing with ±5V supplies is ±4V, with a
single 5V supply it is 1V to 4V, when AGND (Pins 3, 5) is
biased at 2.5V. Table 4 lists op amps that are recom-
mended for use with an LTC1164-8. The LTC1164-8 is
designed and specified for a dual ±5V or single 5V supply
operation. The filter’s passband gain linearity is optimum
at single 5V supply and with Pins 3, 5 (AGND) biased at 2V.
Filter operation at ±7.5V supplies is not tested or speci-
fied. At V
frequencies up to 7kHz. Please refer to the Passband
Variations vs Power Supply graph in the Typical Perfor-
mance Characteristics.
(S/N)
IN
f
= 0.01 • f
= noise bandwidth at the input of the filter
OUT
–18
–12
S
–15
–3
–6
–9
/(S/N)
–1.00
Figure 3. Typical Passband Variations
3
0
PERCENT DEVIATION FROM f
= 7.5V, the filter will operate with center
V
R
R
S
IN
F
CENTER
IN
= 61.9k
= ±5V
= 340k
/(BW)
IN
–0.50
= 20 • Log √(BW)
= noise equivalent filter bandwidth
f
= 20 • Log√3.4kHz/ 0.01 • 1kHz
f
CENTER
CENTER
0.50
(±% f
LTC1164-8 • F03
IN
LTC1164-8
CENTER
/(BW)
1.00
)
f
11648fb
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