Coded data generation or conversion – Analog to or from digital conversion – Differential encoder and/or decoder
Patent
1992-02-21
1993-09-07
Williams, Howard L.
Coded data generation or conversion
Analog to or from digital conversion
Differential encoder and/or decoder
H03M 300
Patent
active
052433455
ABSTRACT:
A sigma-delta modulator comprising a low-pass filter of the Nth order, which is constituted by a series combination of N first-order integrating sections (6.1, 6.2, 6.3, . . . , 6.N) each comprising an integrator (12.1, 12.2, 12.3, . . . , 12. N) and a limiter (14.1, 14.2, 14.3, . . . , 14.N). The individual output signals of the sections are weighted by means of corresponding weighting amplifiers (16.1, 16.2, 16.3, . . . , 16.N) and the weighted signals are added together by an adder stage (18). The gains of the sections and the limit values of the limiters are selected so that the last limiter (14.N) in the series arrangement is activated first as the input signal level to the sigma-delta modulator increases, then the last-but-one limiter, and so on. This reduces the order of the filter system each time by one section as the input signal level increases above each successive limit value, thereby causing the sigma-delta modulator to remain stable at all signal levels.
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Candy et al. "Oversampling Methods for A/D and D/A Conversion", 1992, from IEEE Oversampling Delta-Sigma Data Converters Reprints of Articles from IEEE publications 1962-1990, pp. 1-29.
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Welland et al., "A Stereo 16-Bit Delta-Sigma A/D Converter for Digital Audio", Journal of Audio Engineering Society vol. 37 No. 6, Jun. 1989 pp. 476-485.
Dijkmans Eise C.
Naus Peter J. A.
Nuijten Petrus A. C. M.
Eason Leroy
U.S. Philips Corporation
Williams Howard L.
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