INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS Int. J. Circ. Theor. Appl. 2005; 33:347–351 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/cta.317 LETTER TO THE EDITOR Another FIR lattice structure S. C. Dutta Roy ∗; † and R. Vishwanath ‡ Department of Electrical Engineering; Indian Institute of Technology; Hauz Khas; New Delhi 110016; India SUMMARY A new two multiplier FIR lattice structure is derived by using the digital two-pair concept, which pro- duces two transfer functions H i (z) and H ′ i (z) having the complementary relationship H ′ i (z)= z -i H i (-z -1 ), in contrast to the mirror image relationship, i.e. H ′ i (z)= z -i H i (z -1 ) satised in the con- ventional FIR lattice structure. The new structure should be useful in crossover networks as well as in multirate signal processing. Copyright ? 2005 John Wiley & Sons, Ltd. KEY WORDS: FIR lattice; digital complementary lters; digital signal processing 1. INTRODUCTION In dealing with FIR lattice realizations, standard text books on digital signal processing [1–3] assume the structure shown in Figure 1, and then carry out an analysis to nd out the recurrence relation between the coecients of the transfer function at the ith output H i (z)= X i (z) X 0 (z) =1+ i ∑ n=1 a (i) n z -n ; i = N to 1 (1) and that at the (i - 1)th output, H i-1 (z). Specically, this recurrence relation is a (i-1) n = a (i) n - k i a (i) i-n 1 - k 2 i (2) In the process, one nds that k i = a (i) i (3) ∗ Correspondence to: S. C. Dutta Roy, Department of Electrical Engineering, Indian Institute of Technology, Hauz Khas, New Delhi 110 016, India. † E-mail: scdroy@ee.iitd.ernet.in ‡ E-mail: r vishu hyd@yahoo.co.in Received 26 August 2004 Copyright ? 2005 John Wiley & Sons, Ltd. Revised 1 March 2005