LTC1164-6CJ LINER [Linear Technology], LTC1164-6CJ Datasheet - Page 9

• Manufacturer Part Number: LTC1164-6CJ
• Description: Low Power 8th Order Pin Selectable Elliptic or Linear Phase Lowpass Filter
• Manufacturer: LINER [Linear Technology]

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 100 V
90 V
the filter’s cutoff frequency. The total wideband noise
( V
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 f
instance, an LTC1164-6 operating with a 100kHz clock
and 1kHz cutoff frequency receives a 98.5kHz, 10mV
input signal, a 1.5kHz, 10 V
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.
A
4%, will be aliased back into the filter’s passband. If, for
PPLICATI
RMS
RMS
) is nearly independent of the value of the clock.
of which have frequency contents from DC up to
O
U
S
I FOR ATIO
U
RMS
alias signal will appear at
W
U
RMS
RMS
CLK
,
Table 4. Maximum V
POWER SUPPLY
Table 5. Aliasing (f
INPUT FREQUENCY
f
f
Table 6. Transient Response of LTC Lowpass Filters
LTC1064-3 Bessel
LTC1164-5 Linear Phase
LTC1164-6 Linear Phase
LTC1264-7 Linear Phase
LTC1164-7 Linear Phase
LTC1064-7 Linear Phase
LTC1164-5 Butterworth
LTC1164-6 Elliptic
LTC1064-4 Elliptic
LTC1064-1 Elliptic
* To 50% 5%, ** 10% to 90% 5%, *** To 1% 0.5%
CLK
CLK
LOWPASS FILTER
(V
Single 5V
96 (or 104)
97 (or 103)
98 (or 102)
98.5 (or 101.5)
99 (or 101)
99.5 (or 100.5)
192 (or 208)
194 (or 206)
196 (or 204)
198 (or 202)
199 (or 201)
199.5(or 200.5)
/f
/f
7.5V
5V
IN
C
C
(kHz)
= 100:1, f
= 50:1, f
= 1V
RMS
CUTOFF
)
CUTOFF
CLK
= 2kHz
IN
MAXIMUM f
= 1kHz
= 100kHz)
(Relative to Input)
vs V
1.5MHz
OUTPUT LEVEL
1MHz
1MHz
1MHz
1MHz
1MHz
1MHz
S
0.50/f
0.43/f
0.43/f
1.15/f
1.20/f
1.20/f
0.80/f
0.85/f
0.90/f
0.85/f
DELAY
TIME*
(SEC)
– 68.0
– 65.0
– 60.0
– 68.0
– 63.0
and f
–75.0
– 76.0
(dB)
– 0.5
– 3.2
– 3.4
– 1.3
– 0.9
CLK
C
C
C
C
C
C
C
C
C
C
CLK
TIME**
0.34/f
0.34/f
0.34/f
0.36/f
0.39/f
0.39/f
0.48/f
0.54/f
0.54/f
0.54/f
(SEC)
RISE
1V
3V
0.7V
2.5V
0.5V
0.7V
0.5V
C
C
C
C
C
C
C
C
C
C
MAXIMUM V
LTC1164-6
OUTPUT FREQUENCY
RMS
RMS
(Aliased Frequency)
RMS
RMS
RMS
RMS
RMS
SETTLING OVER-
TIME*** SHOOT
(f
(f
0.80/f
0.85/f
1.15/f
2.05/f
2.20/f
2.20/f
2.40/f
4.30/f
4.50/f
6.50/f
(SEC)
IN
IN
(f
(f
(f
(f
(f
IN
IN
IN
IN
IN
(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
> 35kHz)
> 25kHz)
> 250kHz)
> 25kHz)
> 100kHz)
> 25kHz)
> 100kHz)
C
C
C
C
C
C
C
C
C
C
IN
(%)
0.5
11
18
20
20
0
1
5
5
5
9