CS627x: Advanced filter design
Level: 6
Credit rating: 15
Degree(s) ECS, CE
Prequisites: CS2221, CS2232, CS3291
Co-requisites:
Duration: 12 weeks
Lectures: 24 in total at 2 lectures per week
Example classes: included
Laboratories: None
Assessment: 2 hour exam
Lecturers: B.M.G. Cheetham & Dr. D. King
Aims:
To impart an understanding of the theory of electrical and electronic filters, both
analogue and digital, at a level advanced enough for innovative design in a wide range of
application areas. This requires a fundamental understanding of linear time invariant
circuits and systems, techniques for approximating given filter specifications, and the
techniques available for realising or implementing suitable approximations using real
circuits or computer or DSP hardware. realisations. The course enhances the material
covered in the third year course CS (Digital Signal Processing) and the second year
courses CS (Circuits & Systems) and CS (Signals and Systems).
Learning outcomes:
On successful completion of this course, students should be able to:
(1) understand the requirements of filters as described in typical specifications.
(2) select appropriate filter types for given applications.
(3) calculate the gain and phase responses of analogue and digital filters and recognise
important features.
(4) understand the properties of the most commonly used analogue low-pass gain
response approximations, i.e. Butterworth, Chebychev, Elliptical and Bessel-Thompson
approximations and be able apply frequency band transformations to produce high-pass,
band-pass, band-stop gain response approximations.
(5) design and implement analogue and digital filters as realisations of the
approximations mentioned above..
(6) understand how the phase or group-delay response of a filter affects its performance
and how these responses are related to the gain response.
(7) design FIR and IIR digital filters using the bilinear transformation method the
impulse-response invariance method, windowing methods, the Remez Exchange
Algorithm, frequency sampling and others approaches.
(8) specify digital filter realisations in direct, canonical and other forms and implement
such digital filters on DSP devices
Assessment of Learning Outcomes:
2 hour written examination
Contribution to programme learning outcomes
A2, A3, A5, B1, B2, B3, C4
Reading list and supporting material
"Analogue filter design" ME Van Valkenburg, Holt Rinehart and Winston,
"Microelectronic Circuits" A.S. Sedra and K.C. Smith
"Passive and Active Network Synthesis", A Budak
"Digital Signal Processing", E.C. Ifeachor and BW Jervis, Addison Wesley, 1993
Syllabus
Introduction (2 lectures):
The gain and phase response of an ideal filter and the need for approximation.
Concept of filter design and the different approaches to approximation and realisation.
Specification of filter frequency responses.
Analogue filter approximation techniques (3 lectures):
Butterworth low-pass gain response approximation and its characteristics. Order
estimation. Derivation of all-pole (minimum phase) transfer function by locating the
required poles. Transient response of a Butterworth low-pass filter. Cascading second
order transfer functions to obtain higher orders.
Chebychev, Elliptical and Bessel-Thompson low-pass gain approximations and
derivation of transfer functions.
Analogue filter realisation (4 lectures):
First and second order active filter sections.
The Tow Thomas biquadratic section and Scallen Key sections.
Lowpass, high pass and bandpass active filter realisations by cascading sections.
Further active realisations (1 lecture).
State-variable realisation. and switched capacitor filters.
Magnitude and phase response design (2 lectures) :
Phase responses of minimum phase system functions. Hilbert transform relationship
between the magnitude and phase responses. All-pass system functions. Phase
equalisation.
Digital filter design techniques (2 lectures)
Review of digital filters design techniques covered in CS3291. Advanced design
problems using these techniques.
Design of finite impulse response (FIR) digital filters (3 lectures)
The frequency sampling method, the Remez exchange algorithm, windowing methods
and others approaches.
Design of infinite impulse response (IIR) digital filters (3 lectures)
The impulse and step response invariant techniques. Further design techniques based on
the bilinear transformation method and other approaches.
Digital filter realisations (2 lectures)
The effect of finite arithmetic and quantisation error. Serial and parallel realisations.
Direct, canonical and other forms. Implementation of digital filters on 'DSP'
microprocessors.
Discussion of exercises and problems (2 lecture slots)