Filter Design
Course Objective:
To familiarize student with the concept of analog filter design: passive filters, RC active filters and switchedcapacitor filters.
 Introduction[4 hours]
 Filter and its importance in communication
 Kinds of filters in terms of frequency response
 Ideal response and response of practical filters
 Normalization and denormalization in filter design
 Impedance (magnitude) scaling and frequency scaling
 History of filter design and available filter technologies
 Approximation Methods[8 hours]
 Approximation and its importance in filter design
 Lowpass approximations methods
 Butterworth response, Butterworth pole locations, Butterworth filter design from specifications
 Chebyshev and inverse Chebyshev characteristics, network functions and pole zero locations
 Characteristics of Cauer (elliptic) response
 BesselThomson approximation of constant delay
 Delay Equalization
 Frequency transformation[2 hours]
 Frequency transformation and its importance in filter design
 Lowpass to highpass transformation
 Lowpass to bandpass transformationÂ and
 Lowpass to bandstop transformation
 Properties and Synthesis of Passive Networks[7 hours]
 Oneport passive circuits
 Properties of passive circuits, positive real functions
 Properties of lossless circuits
 Synthesis of LC oneport circuits, Foster and Cauer circuits
 Properties and synthesis of RC oneport circuits
 Twoport Passive Circuits
 Properties of passive twoport circuits, residue condition, transmission zeros
 Synthesis of twoport LC and RC ladder circuits based on zeroshifting by partial pole removal
 Design of ResistivelyTerminated Lossless Filter[4 hours]
 Properties of resistivelyterminated lossless ladder circuits, transmission and reflection coefficients
 Synthesis of LC ladder circuits to realize allpole lowpass functions
 Synthesis of LC ladder circuits to realize functions with finite transmission zeros
 Active Filter[7 hours]
 Fundamentals of Active Filter Circuits
 Active filter and passive filter
 Ideal and real operational amplifiers, gainbandwidth product
 Active building blocks: amplifiers, summers, integrators
 First order active sections using inverting and noninverting opamp configuration
 Second order active sections (biquads)
 TowThomas biquad circuit, design of active filter using TowThomas biquad
 SallenKey biquad circuit and Multiplefeedback biquad (MFB) circuit
 Gain reduction and gain enhancement
 RCCR transformation
 Sensitivity[3 hours]
 Sensitivity and importance of sensitivity analysis
 Definition of single parameter sensitivity
 Centre frequency and Qfactor sensitivity
 Sensitivity properties of biquads
 Sensitivity of passive circuits
 Design of HighOrder Active Filters[6 hours]
 Cascade of biquads
 Sequencing of filter blocks, center frequency, Qfactor and gain
 Active simulation of passive filters
 Ladder design with simulated inductors
 Ladder design with frequencydependent negative resistors (FDNR)
 Leapfrog simulation of ladders
 SwitchedCapacitor Filters[4 hours]
 The MOS switch and switched capacitor
 Simulation of resistor by switched capacitor
 Switchedcapacitor circuits for analog operations: addition, subtraction, multiplication and integration
 Firstorder and secondorder switchedcapacitor circuits
Practical:
The laboratory experiments consist computer simulation as well hardware realization for analysis and design of passive and active filters which include.
 Analysis and design of passive & active filter circuits using computer simulation
 Design of active filters using biquad circuits
 Design of higher order active filters using inductor simulation
 Design of higher order active filters using functional simulation
References:
 Design of Analog Filters By: Rolf Schaumann, Mac E. Van Valkenburg
 Passive and Active Filters (Theory and Implementations) By: WaiKai Chen
 Analog Filter, KendalÂ L Su
Evaluation Scheme:
Unit 
Hour 
Marks Distribution* 
1 
4 
7 
2 
8 
14 
3 
2 
4 
4 
7 
13 
5 
4 
7 
6 
7 
12 
7 
3 
5 
8 
6 
11 
9 
4 
7 
Total 
45 
80 
*Note: There may be minor deviation in marks distribution.
