MAX7401 查看數據表（PDF） - Maxim Integrated

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MAX7401

8th-Order, Lowpass, Bessel, Switched-Capacitor Filters

Maxim Integrated 

8th-Order, Lowpass, Bessel,

Switched-Capacitor Filters

Table 1. Typical Harmonic Distortion

FILTER

fCLK

fC

fIN

(kHz)

(kHz)

(Hz)

100

MAX7401

500

100

MAX7405

500

1

200

5

1000

1

200

5

1000

VIN

(Vp-p)

4

2

TYPICAL HARMONIC DISTORTION (dB)

2nd

3rd

4th

5th

-91

-83

-90

-93

-89

-79

-92

-92

-87

-83

-87

-88

-83

-82

-88

-88

V+

INPUT IN

VDD

SHDN *

OUT OUTPUT

COM

MAX7401

V+

CLOCK

CLK

MAX7405 OS

V-

0.1µF

0.1µF

GND

V-

*DRIVE SHDN TO V- FOR LOW-POWER SHUTDOWN MODE.

Figure 4. Dual-Supply Operation

GND to the negative supply. Figure 4 shows an example

of dual-supply operation. Single- and dual-supply perfor-

mance are equivalent. For either single- or dual-supply

operation, drive CLK and SHDN from GND (V- in dual-

supply operation) to VDD. For ±5V dual-supply applica-

tions, use the MAX291–MAX297.

Input Signal Amplitude Range

The optimal input signal range is determined by observ-

ing the voltage level at which the total harmonic distor-

tion plus noise (THD+N) is minimized for a given corner

frequency. The Typical Operating Characteristics show

graphs of the devices’ THD+N response as the input

signal’s peak-to-peak amplitude is varied. These mea-

surements are made with OS and COM biased at mid-

supply.

Anti-Aliasing and Post-DAC Filtering

When using the MAX7401/MAX7405 for anti-aliasing or

post-DAC filtering, synchronize the DAC and the filter

clocks. If the clocks are not synchronized, beat frequen-

cies may alias into the passband.

The high clock-to-corner frequency ratio (100:1) also

eases the requirements of pre- and post-SCF filtering. At

the input, a lowpass filter prevents the aliasing of fre-

quencies around the clock frequency into the passband.

At the output, a lowpass filter attenuates the clock

feedthrough.

A high clock-to-corner frequency ratio allows a simple

RC lowpass filter, with the cutoff frequency set above

the SCF corner frequency, to provide input anti-aliasing

and reasonable output clock attenuation.

Harmonic Distortion

Harmonic distortion arises from nonlinearities within the

filter. These nonlinearities generate harmonics when a

pure sine wave is applied to the filter input. Table 1 lists

the MAX7401/MAX7405’s typical harmonic-distortion

values with a 10kΩ load at TA = +25°C.

Chip Information

TRANSISTOR COUNT: 1116

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