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Abstract-A new algorithm and hardware implementation of the Viterbi squaring function has been developed. The use of an approximation squaring technique preserves the Viterbi performance as is demonstrated by Monte-Carlo simulations. Additionally, the 16-bit approximate squaring implementation is expected to require one-fourth the area and operate at three times the speed of the conventional squaring implementation.

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A new architecture for Nyquist-rate analog-to-digital (A/D) conversion is presented. The new architecture combines the concept of time-interleaved A/D converters with the 16 A/D converter. For every doubling of the clock frequency, the resolution of the A/D converter improves by bits, where is the order of the 16 modulators. The advantage of the time-interleaved 16 A/D converter is reduced complexity of the digital filters. Another feature of this architecture is that the linearity of the converters depends on the linearity of each channel and is independent of the number of channels. Index Terms-Analog-to-digital (A/D) converter, Nyquist rate A/D converter, parallel 16, time interleaved A/D converter.

This paper describes an analog-to-digital converter which combines multiple delta-sigma modulators in parallel so that time oversampling may be reduced or even eliminated. By doubling the number of Lth-order delta-sigma modulators, the resolution of this architecture is increased by approximately L bits. Thus, the resolution obtained by combining M delta-sigma modulators in parallel with no oversampling is similar to operating the same modulator with an oversampling rate of M. A parallel delta-sigma A/D converter implementation composed of two, four, and eight second-order delta-sigma modulators is described that does not require oversampling. Using this prototype, the design issues of the parallel delta-sigma A/D converter are explored and the theoretical performance with no oversampling and with low oversampling is verified. This architecture shows promise for obtaining high speed and resolution conversion since it retains much of the insensitivity to nonideal circuit behavior characteristic of the individual delta-sigma modulators.

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