Cirrus-logic AN048 Instrukcja Użytkownika Pobierz pdf

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AN48

Application Note

DESIGNNOTESFORA2-POLEFILTERWITH

DIFFERENTIAL INPUT

by Steven Green

1. Introduction

Many of today’s Digital-to-Analog Converters

(DACs) require a circuit that has a differential input

and will remove common-mode errors, reduce the

out-of-band noise produced by the delta-sigma

modulator and produce a single-ended output. The

circuit in Figure 1 includes a differential input and a

two-pole analog filter to achieve these design re-

quirements. This application note outlines the de-

sign steps required to select component values.

Notice the similarities between Figure 1 and the

multiple-feedback low-pass filter shown in

Figure 2. The 2-Pole Low-Pass Filter with Differen-

tial Input is easily designed using the design equa-

tions for the multiple-feedback low-pass filter. Also,

notice the similarities between Figure 1 and

Figure 3. The differential input function is accom-

plished by simply duplicating the component val-

ues generated in the filter design

Figure 1. 2-Pole Low-Pass Filter with Differential Input

AIN-

AIN+

MAR ‘03

AN48REV2

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Podsumowanie treści

Strona 1 - Application Note

Strona 2

AN4822. Design StepsStep 1: Determine the required pass band gain,Ho. The circuit parameters require that the magni-tude of Hobe greater than or equal

Strona 3 - 3. Design Example

AN483Step 6: Review the resistor and capacitor values.It is desirable to keep the capacitor values suffi-ciently large to minimize the effects of stra

Strona 4 - REFERENCES

AN484.REFERENCES[1] C. L. Lindquist, “Active Network Design with Signal Filtering Applications”, Steward & Sons[2] A. B. Williams, “Electronic Fil

Strona 5 - • Notes •

• Notes •

Strona 6