Filter Design
Filters are signal-processing circuits used to modify the frequency spectrum of an electrical signal. They may be used to amplify, attenuate, or reject a certain range of frequencies of their input signals. Filters are pervasive in integrated circuits because of their vast number of applic...
Circuit Sage Tools
ANALOG FILTERS
Sallen-Key Mathcad filters routine:
Extensive Mathcad routine for designing integrated Sallen-Key filters
Sallen-Key Mathcad filters routine (pdf):
.pdf file of Sallen-Key Matchcad routine
Mathcad routine for Butterworth filters:
Mathcad routine for LC Butterworth filters
Mathcad routine for elliptic filters:
Mathcad routine for LC elliptic filters
Mathcad routine for Chebyshev filters:
Mathcad routine for LC Chebyshev filters
2nd Order Low-Q Active Filter Design:
This tool calculates the required resistor and capacitor values for a second order low-Q active filter.
Single Pole Active Filter Design:
This tool calculates the required resistor and capacitor values for a single pole active filter.
Online Tools
ANALOG FILTERS
Neil Barnes' Filter:
Intuitive filter program for Windows, can process a .WAV file. Windows-95-looking interface
FilterShop:
$1500 tool can design almost any filter
FilterCAD (FREE):
Linear Technology's filter design tool
eSeptum:
Waveguide filter design tool
FilterSolutions:
Free, Light, and Full versions available
Cocafil:
Waveguide coupled-cavity filters
Elsie:
Time- and frequency-domain plots, S-parameters, Monte Carlo, etc. Student edition FREE
Helical:
Bandpass filter design and analysis program based on the helical resonator
Butterworth filter routine in BASIC:
BASIC code implements different Butterworth filter responses
BASIC filter routines:
Tom Couthbert's BASIC routines for filter design
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Online Articles
ANALOG FILTERS
Sallen-Key Butterworth 5th order LPF design:
Design and implementation of a 10-kHz, 5th order active filter
LPF tutorial:
Design of a low sensitivity Sallen Key LPF
Ian Purdie LC filter tutorial:
Scroll down to Section 5
TI"s analysis of the Sallen-Key arquitecture:
Analysis and lab data of low- and high-pass Sallen Key filters
TI's Filters for data transmission:
Analysis of what happens when digital signals are filtered
TI Active Low-Pass Filter Design:
Butterworth, Chebyshev, Bessel, Sallen-Key, and MFB active filter design
U. of San Diego's overview of microwave filters:
Goes over distributed and lumped implementations of microwave filters
Queens University's wiki page on microwave filters:
Discusses prototyping and going from lumped to distributed implementations
ARRL RF Filters page:
Links to ARRL articles and a picture of commonly used RF filter topologies
National's Introduction to filters:
Goes over active, passive, and switched-capacitor filter types
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Books
Filtering in the Time and Frequency Domains by H. Blinchikoff and A. Zverev:
Re-print of a 1976 book considered a classic by many
Generalized Filter Design by Computer Optimization:
CAD techniques for RF/microwave filter optimization
Passive, Active, and Digital Filters by Wai-Kai Chen:
Compilation of both analog and digtal filters
Mathematics for Circuits and Filters by Wai-Kai Chen:
from back cover: "...stresses the fundamental theory behind professional applications, making an excellent, flexible resource that enables easy access to the information needed to deal with circuits and filters..."
The Circuits and Filters Handbook by Wai-Kai Chen:
Compilation of articles by many authors, almost 3000 pages.
Electronic Filter Analysis and Synthesis by Michael Ellis:
1994 book, from description: "...helps you save time and effort in writing CAD and analysis programs for electronic filters, and provides explicit details on how to synthesize lowpass, bandpass, bandstop, and highpass realizations for passive, active, digital and switched capacitors...."
Modern Filter Design: Active Rc and Switched Capacitor by Mohammed Shuaib Ghausi:
Re-print of 1981 book. From description: "...the authors discuss the design of continuous-time, second order active sections (biquads), various measures of sensitivity, and the basic properties and classification of continuous-time and sampled data systems, together with filter transfer functions and approximations..."
Active Filter Cookbook by Don Lancaster:
From description: "...It gives you everything you need to know to build active lowpass, bandpass, and highpass filters...."
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