LTC1164-6(Rev0) 查看數據表（PDF） - Linear Technology
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LTC1164-6
(Rev.:Rev0)
(Rev.:Rev0)
Linear Technology
LTC1164-6 Datasheet PDF : 12 Pages
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LTC1164-6
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 fre-
quency 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.
Wideband Noise
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-to-
cutoff frequency of 50:1, aliasing occurs at twice the clock
frequency. Table 5 shows details.
Table 4. Maximum VIN vs VS and fCLK
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)
INPUT FREQUENCY
(VIN = 1VRMS)
(kHz)
OUTPUT LEVEL
(Relative to Input)
(dB)
fCLK/fC = 100:1, fCUTOFF = 1kHz
96 (or 104)
–75.0
97 (or 103)
– 68.0
98 (or 102)
– 65.0
98.5 (or 101.5)
– 60.0
99 (or 101)
– 3.2
99.5 (or 100.5)
– 0.5
fCLK/fC = 50:1, fCUTOFF = 2kHz
192 (or 208)
– 76.0
194 (or 206)
– 68.0
196 (or 204)
– 63.0
198 (or 202)
– 3.4
199 (or 201)
– 1.3
199.5(or 200.5)
– 0.9
OUTPUT FREQUENCY
(Aliased Frequency)
(kHz)
4.0
3.0
2.0
1.5
1.0
0.5
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 SETTLING OVER-
TIME** TIME*** SHOOT
(SEC) (SEC) (%)
LTC1064-3 Bessel
LTC1164-5 Linear Phase
LTC1164-6 Linear Phase
0.50/fC 0.34/fC 0.80/fC 0.5
0.43/fC 0.34/fC 0.85/fC 0
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
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