{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

op-amp_active filters

op-amp_active filters - Chapter 16 Active Filter Design...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 16 Active Filter Design Techniques Literature Number SLOA088 Excerpted from Op Amps for Everyone Literature Number: SLOD006A
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
16-1 Active Filter Design Techniques Thomas Kugelstadt 16.1 Introduction What is a filter? A filter is a device that passes electric signals at certain frequencies or frequency ranges while preventing the passage of others . — Webster. Filter circuits are used in a wide variety of applications. In the field of telecommunication, band-pass filters are used in the audio frequency range (0 kHz to 20 kHz) for modems and speech processing. High-frequency band-pass filters (several hundred MHz) are used for channel selection in telephone central offices. Data acquisition systems usually require anti-aliasing low-pass filters as well as low-pass noise filters in their preceding sig- nal conditioning stages. System power supplies often use band-rejection filters to sup- press the 60-Hz line frequency and high frequency transients. In addition, there are filters that do not filter any frequencies of a complex input signal, but just add a linear phase shift to each frequency component, thus contributing to a constant time delay. These are called all-pass filters. At high frequencies (> 1 MHz), all of these filters usually consist of passive components such as inductors (L), resistors (R), and capacitors (C). They are then called LRC filters. In the lower frequency range (1 Hz to 1 MHz), however, the inductor value becomes very large and the inductor itself gets quite bulky, making economical production difficult. In these cases, active filters become important. Active filters are circuits that use an op- erational amplifier (op amp) as the active device in combination with some resistors and capacitors to provide an LRC-like filter performance at low frequencies (Figure 16–1). L R C V IN V OUT V IN V OUT R 1 C 1 C 2 R 2 Figure 16–1. Second-Order Passive Low-Pass and Second-Order Active Low-Pass Chapter 16
Image of page 2
Fundamentals of Low-Pass Filters 16-2 This chapter covers active filters. It introduces the three main filter optimizations (Butter- worth, Tschebyscheff, and Bessel), followed by five sections describing the most common active filter applications: low-pass, high-pass, band-pass, band-rejection, and all-pass fil- ters. Rather than resembling just another filter book, the individual filter sections are writ- ten in a cookbook style, thus avoiding tedious mathematical derivations. Each section starts with the general transfer function of a filter, followed by the design equations to cal- culate the individual circuit components. The chapter closes with a section on practical design hints for single-supply filter designs. 16.2 Fundamentals of Low-Pass Filters The most simple low-pass filter is the passive RC low-pass network shown in Figure 16–2.
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern