AN2317 - Application

External Circuit Design

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1.2

Anti-aliasing Filter

The anti-aliasing filter (

Figure 5) is a low-pass filter. It reduces high frequency levels which

may cause distortion due to the sampling (aliasing) that occurs before the analog inputs of

an analog-to-digital converter (ADC) are introduced into the application (see

Figure 6).

Filtering is easily implemented with a resistor-capacitor (RC) single-pole circuit which

obtains an attenuation of –20dB/dec.

Figure 5.

Anti-aliasing Filter

Figure 6.

Anti-aliasing Effect

R

R

UO

UI

C

C

AI12900

0

2

450

900

Frequency - kHz

Image

Frequencies

AI12901