Two second-order, multiple-output digital-filter structures are described which realize simultaneously a low-pass, a high-pass, a bandpass, a notch, and an all-pass transfer function. The two structures can be stabilized with respect to limit-cycle oscillations by employing the techniques of magnitude truncation and controlled rounding, and each uses four multipliers and two unit delays. The two structures are attractive for VLSI implementation since each can serve as the basis of a versatile, universal digital-filter chip which can be used for the implementation of Butterworth, Chebyshev, and elliptic digital filters and also for the design of digital equalizers. © 1987 IEEE

K. Manivannan

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Universal digital biquads which are free of limit cycles

IEEE Transactions on Circuits and Systems

A new form of complex biquad recursive digital structure is proposed which is based on the concept of generalized immittance converter. Orthogonal filters which are widely used in TDM-FDM transmultiplexers can be obtained as a special class of these complex biquads. It is shown that the proposed structure is completely free from zero-input limit cycles under linear conditions and further the stability under finite arithmetic conditions can be achieved using the technique of magnitude truncation. It is also shown that for this new structure, the stability of the forced response can be ensured for certain types of overflow nonlinearities. © 1989 IEEE

Limit-Cycle Free Complex Biquad Recursive Digital Filters

The constant-input stability of the GIC digital filter structures proposed by Antoniou and Rezk [1] is investigated in this paper. This stability is essential for these structures since they are used in cascade form. It is shown that only one of the five sections proposed in [1] can be stabilized against constant-input limit cycles. It is also shown that each one of the five filter sections of [1] can be made to realize multiple transfer functions without any additional multiplier. An universal filter based on the GIC concept is proposed which realizes simultaneously all the five standard second-order transfer functions and which is also free from both zero-and constant-input limit cycles. The sensitivity and noise properties of the proposed universal filter are compared with those of other known universal structures for a specific example. © 1989 IEEE

Constant-Input Stability and Multiple-Output Realization of the GIC Digital Filters

Networks

Practical network design techniques, by Gilbert Held, Wiley, New York, 1991, 257 pp

A general method for deriving digital-filter structures from corresponding RC-active configurations is presented. The method is then used to derive digital-filter structures from various low-sensitivity RC-active configurations such as the three-amplifier state-variable biquad, and the corresponding summing four-amplifier biquad. The new digital structures are found to have the salient features of the reference configurations. For example, the structures based on the summing four-amplifier biquad embody the simultaneous realization of a variety of filter transfer functions, namely, a low-pass, a bandpass, and a general biquadratic transfer function. In addition, it is shown that in these structures, limit cycles can be eliminated by using a known technique based on magnitude truncation. © 1984 IEEE

Journal	IEEE Transactions on Circuits and Systems
ISSN	00984094
Open Access	No