Operational Amplifier Circuits

CHAPTER

5

Introduction

to

Active

Filters

5.1

Preliminary

Comments

Filters are networks whose gain (or attenuation) and associated phase shift

vary with frequency. This frequency dependency can be exploited in order to

separate wanted and unwanted components of a signal on the basis of fre-

quency. In general, filters consist of linear elements such as resistors, capaci-

tors,

and inductors, although useful filters can be constructed using any two of

these. Inductors are widely used at radio frequencies where the required values

are a convenient size. At lower frequencies, resistance-capacitance filters tend

to predominate in view of the physica ...