PSpice for Digital Signal Processing

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1 PSpice for Digital Signal Processing

2 Copyright 2007 by Morgan & Claypool All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means electronic, mechanical, photocopy, recording, or any other except for brief quotations in printed reviews, without the prior permission of the publisher. PSpice for Digital Signal Processing Paul Tobin ISBN: ISBN: ISBN: ISBN: paperback paperback ebook ebook DOI /S00073ED1V01Y200612DCS011 A Publication in the Morgan & Claypool Publishers series SYNTHESIS LECTURES ON DIGITAL CIRCUITS AND SYSTEMS #11 Lecture #11 Series Editor: Mitchell A. Thornton, Southern Methodist University Library of Congress Cataloging-in-Publication Data Series ISSN: print Series ISSN: electronic First Edition

3 PSpice for Digital Signal Processing Paul Tobin School of Electronic and Communications Engineering Dublin Institute of Technology Ireland SYNTHESIS LECTURES ON DIGITAL CIRCUITS AND SYSTEMS #11 M &C Morgan & Claypool Publishers

4 iv ABSTRACT PSpice for Digital Signal Processing is the last in a series of five books using Cadence Orcad PSpice version 10.5 and introduces a very novel approach to learning digital signal processing (DSP). DSP is traditionally taught using Matlab/Simulink software but has some inherent weaknesses for students particularly at the introductory level. The plug in variables and play nature of these software packages can lure the student into thinking they possesses an understanding they don t actually have because these systems produce results quickly without revealing what is going on. However, it must be said that, for advanced level work Matlab/Simulink really excel. In this book we start by examining basic signals starting with sampled signals and dealing with the concept of digital frequency. The delay part, which is the heart of DSP, is explained and applied initially to simple FIR and IIR filters. We examine linear time invariant systems starting with the difference equation and applying the z-transform to produce a range of filter type i.e. low-pass, high-pass and bandpass. The important concept of convolution is examined and here we demonstrate the usefulness of the log command in Probe for giving the correct display to demonstrate the flip n slip method. Digital oscillators, including quadrature carrier generation, are then examined. Several filter design methods are considered and include the bilinear transform, impulse invariant, and window techniques. Included also is a treatment of the raised-cosine family of filters. A range of DSP applications are then considered and include the Hilbert transform, single sideband modulator using the Hilbert transform and quad oscillators, integrators and differentiators. Decimation and interpolation are simulated to demonstrate the usefulness of the multi-sampling environment. Decimation is also applied in a treatment on digital receivers. Lastly, we look at some musical applications for DSP such as reverberation/echo using realworld signals imported into PSpice using the program Wav2Ascii. The zero-forcing equalizer is dealt with in a simplistic manner and illustrates the effectiveness of equalizing signals in a receiver after transmission. KEYWORDS Digital frequency, sampling, delays, difference equations, z-transform, FIR and IIR filters, convolution, windowing, filter design methods, Hilbert transform, decimation and interpolation, digital receivers.

5 I would like to dedicate this book to my wife and friend, Marie and sons Lee, Roy, Scott and Keith and my parents (Eddie and Roseanne), sisters, Sylvia, Madeleine, Jean, and brother, Ted.

7 vii Contents 1. IntroductiontoDigitalSignalProcessing Sampling Aliasing TheADCParameters DigitalFrequency DigitalSamples DelayUnitandHierarchicalBlocks TransmissionLineDelay LaplaceDelay DSPSignals:UnitStepSignal UnitImpulseSignal Decaying Exponential Signal DigitalSequences The z-transform UnitImpulse UnitStep UnitDelay Exercises Difference Equations and the z-transform LinearTime-InvariantSystems DifferenceEquations DigitalFilterClassification First-OrderFirFilter z-transformsanddifferenceequations Pole-Zero Constellation and Bibo Stability Cut-OffFrequency InfiniteImpulseResponseFilter First-OrderLow-PassIIRFilter Cut-OffFrequencyfortheIIRFilter...25

8 viii PSPICE FOR DIGITAL SIGNAL PROCESSING IIRPhaseResponse High-PassIIRFilter The 3dBCut-OffFrequency PassbandGain StepResponse ImpulseTesting BandpassIIRDigitalFilter BandpassPole ZeroPlot The 3dBCut-OffFrequency BandpassImpulseResponse SimulatingDigitalFiltersUsingaNetlist DigitalFiltersUsingaLaplacePart Third-OrderEllipticalFilter GroupDelay Exercises Digital Convolution, Oscillators, and Windowing DigitalConvolution FlipandSlipMethod DSPSinusoidalOscillator Exercises DigitalFilterDesignMethods FilterTypes Directform1Filter Directform2Filter TheTransposeFilter Cascade and Parallel Filter Realizations DigitalFilterSpecification TheBilinearTransform DesigningDigitalFiltersUsingtheBilinearTransformMethod TheImpulse-InvariantFilterDesignTechnique Impulse Function Generation SamplingtheImpulseResponse Mapping from the s -Plane to the z-plane TruncatingIIRResponsestoShowGibbsEffect DesigningSecond-OrderFiltersUsingtheImpulse-InvariantMethod Windowing

9 CONTENTS Windows Plots Windows Spectral Plots WindowFilterDesign BartlettWindow TheSampledImpulseResponse ImpulseResponseofaBrick-WallFilter DesigningFiltersUsingtheWindowMethod FIRRoot-RaisedCosineFilter RaisedCosineFIRFilterDesign Root-RaisedCosineFIRFilterDesign Exercises DigitalSignalProcessingApplications Telecommunication Applications QuadratureCarrierSignals Hilbert Transform The Hilbert Impulse Response The Hilbert Amplitude and Phase Responses Single-SidebandSuppressedCarrierModulation Differentiator Integrator MultirateSystems:DecimationandInterpolation Decimation Example Solution Aliasing Interpolation DecimationandInterpolationforNonintegerSamplingFrequencies Exercises Down-Sampling and Digital Receivers ReceiverDesign RFSampling Down-SamplingaPassbandSignal Down-SamplingaSingle-SidebandSignal DigitalReceiver DSPandMusic PhasingEffect ix

10 x PSPICE FOR DIGITAL SIGNAL PROCESSING 6.5 Zero-ForcingEqualizer Three-TapZero-ForcingEqualizer Example Solution Exercises AppendixA:References Books Internet AppendixB:Tables Index AuthorBiographies

PSpice for Digital Communications Engineering

PSpice for Digital Communications Engineering Copyright 2007 by Morgan & Claypool All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any