Datasheet

8th-Order, Lowpass,
Switched-Capacitor Filters
order continuous lowpass filter. This filter is convenient for
anti-aliasing applications, or for clock noise attenuation at
the switched-capacitor filter’s output. Figure 4 shows a
2nd-order lowpass Butterworth filter built using the
uncommitted op amp with a 10kHz corner frequency.
This filter’s input resistance of 22k satisfies the minimum
load requirements of the switched-capacitor filter.
The uncommitted op amp (with a 2MHz gain bandwidth
product) can alternatively be used at the input of the
switched-capacitor filter to help reduce any possible
clock ripple feedthrough to the output.
DAC Post-Filtering
When using the MAX291/MAX292/MAX295/MAX296 for
DAC post-filtering, synchronize the DAC and the filter
clocks. If clocks are not synchronized, beat frequen-
cies will alias into the desired passband. The DAC’s
clock should be generated by dividing down the
switched-capacitor filter’s clock.
Harmonic Distortion
Harmonic distortion arises from nonlinearities within the
filters. These nonlinearities generate harmonics when a
pure sine wave is applied to the filter input. Table 2 lists
typical harmonic distortion values for the MAX291/
MAX292/MAX295/MAX296 with a 1kHz 5Vp-p sine-wave
input signal, a 1MHz clock frequency, and a 5kΩ load.
MAX29_
4
C1
330pF
3
INPUT
C2
1500pF
22k
R1
22k
R2
22k
R3
OUTPUT
OP OUT
OP IN
Figure 4. Uncommitted Op Amp Configured as a 2nd-Order
Butterworth Lowpass Filter (F
o
= 10kHz)
Table 2. Typical Harmonic Distortion (dB)
-96
-92
-82
-83
-96
-97
-88
-89
-71
-93
-71
-72
-89
-86
-82
-78
4th 5th2nd 3rd
Filter
Harmonic
MAX296
MAX295
MAX292
MAX291
_Ordering Information (continued)
* Contact factory for dice specifications.
** Contact factory for availability and processing to MIL-STD-883.
Pin Configuration is 8-pin DIP/SO.
8 CERDIP**-55°C to +125°CMAX296MJA
16 Wide SO
8 Plastic DIP
Dice*0°C to +70°C
-40°C to +85°C
-40°C to +85°CMAX296EWE
16 Wide SO0°C to +70°C
MAX296EPA
MAX296C/D
MAX296CWE
8 Plastic DIP
8 CERDIP**
16 Wide SO-40°C to +85°C
-55°C to +125°C
0°C to +70°C
MAX296CPA
MAX295MJA
MAX295EWE
8 Plastic DIP-40°C to +85°CMAX295EPA
Dice*
16 Wide SO0°C to +70°C
0°C to +70°CMAX295C/D
8 Plastic DIP0°C to +70°C
MAX295CWE
MAX295CPA
8 CERDIP**-55°C to +125°CMAX292MJA
16 Wide SO
8 Plastic DIP
Dice*0°C to +70°C
-40°C to +85°C
-40°C to +85°CMAX292EWE
16 Wide SO0°C to +70°C
MAX292EPA
MAX292C/D
MAX292CWE
PIN-PACKAGETEMP. RANGEPART
8 Plastic DIP0°C to +70°C
MAX292CPA
8 SO0°C to +70°CMAX292CSA
8 SO-40°C to +85°CMAX292ESA
8 SO0°C to +70°CMAX295CSA
8 SO-40°C to +85°CMAX295ESA
8 SO0°C to +70°CMAX296CSA
8 SO-40°C to +85°CMAX296ESA
MAX291/MAX292/MAX295/MAX296
8
Maxim Integrated