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Outline. IIR Filter StructuresDirect Form ITranspose Direct Form IDirect Form IITranspose Direct Form IICascade of Second Order SectionsIteration BoundPipelining IIR FiltersFirst-order IIR FiltersHigher-order IIR FiltersIIR Filter Implementation IssuesDatapath quantizationCoefficient qua
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1. ECE 699—Digital Signal Processing Hardware ImplementationsLecture 5
IIR Filters, Iteration Bound
2/18/09
2. Outline IIR Filter Structures
Direct Form I
Transpose Direct Form I
Direct Form II
Transpose Direct Form II
Cascade of Second Order Sections
Iteration Bound
Pipelining IIR Filters
First-order IIR Filters
Higher-order IIR Filters
IIR Filter Implementation Issues
Datapath quantization
Coefficient quantization
Limit cycles
3. Reading IIR Structures and Implementation Issues
Proakis, Digital Signal Processing
Chapter 9 (4th Edition) = Chapter 7 (3rd Edition)
Iteration Bound
Parhi, VLSI Digital Signal Processing Systems
Chapter 2
Pipelining IIR Filters
Parhi, VLSI Digital Signal Processing Systems
Chapter 10 (Sections 10.1 – 10.4)
4. IIR Filters
5. IIR Filter Use Scenarios In general, specified spectrum shape in the frequency domain can be implemented with fewer taps in an IIR filter than with an FIR filter
Fewer taps = lower area, power, etc.
However IIR filters can have undesirable effects
Not linear phase
Stability issues (poles outside H(z) unit circle)
Implementation issues
6. IIR Filter Difference Equation IIR filter defined by difference equation IIR = finite impulse response N feedback coefficients (N = order of the system) determine poles in system Poles outside unit circle of H(z) cause instability M +1 feedforward coefficients In the z domain: