Performance Analysis in Higher-Order IIR Filter Structures with Application to EEG Signal


This paper investigates the analysis of critical path delay in various infinite impulse response (IIR) digital filter structure implementations. The critical path delay increases with the order of filter increasing in all conventional structures. So, it is needed to reduce the critical path delay for the faster realization of a digital filter in real-time processing. This paper proposed the rules for taking efficient cutset to retime the higher-order IIR filter structure. By applying this proposed retiming/pipelining techniques to EEG preprocessing filter, the critical path delay is \(28\%\), \(23\%\) and \(18\%\) more reduced as compared to the traditional retiming in direct form, parallel and lattice-ladder structure, respectively. These newly retimed structures are simulated in MATLAB Simulink and converted to fixed-point arithmetic for the synthesis of structures on Virtex-5 implementation. The results in different structures show that the allpass-based IIR structures has the lowest critical path delay and lowest computational complexity as compared to the conventional structures. Also, the proposed retimed structure has a smaller slice-delay product and support the largest maximum sampling frequency but requires more slice lookup tables (LUTs) than a conventional structure.

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Data availability

The data that support the finding of this study are available in the institute Shri Guru Gobind Singhji Institute of Engineering and Technology, Vishnupuri, Nanded, Maharashtra, India. One of my supervisor and his research group at this institute has collected the EEG data for cognitive load analysis [3].


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This research was supported by Ministry of Electronics and Information Technology, Govt. of India under Visvesvaraya Ph.D. scheme implemented by Digital India Corporation with reference number: PhD-MLA/4(67/2015-16). We are thankful to editor and anonymous reviewers for their constructive comments which resulted in enhancing the overall quality of the manuscript.

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Correspondence to Mahesh Y. Ladekar.

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A Retimed IIR Filter Structures for Order \(N=4\) and \(N=5\)

A Retimed IIR Filter Structures for Order \(N=4\) and \(N=5\)

This section gives the additional figures of retimed IIR filter structures for order of filter \(N=4\) in Fig. 7 and \(N=5\) in Fig. 8. The allpass-based structure for \(N=5\) is given in Fig. 9.

Fig. 7

Original and retimed IIR structures for \(N=4\)

Fig. 8

Original and retimed IIR structures for \(N=5\)

Fig. 9

Coupled allpass-based IIR structures for \(N=5\)

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Ladekar, M.Y., Joshi, Y.V. & Manthalkar, R.R. Performance Analysis in Higher-Order IIR Filter Structures with Application to EEG Signal. Circuits Syst Signal Process (2021).

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  • Retiming
  • Infinite impulse response (IIR) filter
  • Data flow graph (DFG)
  • Critical path delay (CPD)