US 7,324,030 B2 Jan. 29, 2008
(54) MULTIPLE STAGE DELTA SIGMA MODULATORS
(75) Inventor: Tom Riley, Osgoode (CA)
(73) Assignee: Kaben Wireless Silicon Inc., Ottawa, Ontario (CA)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 11/529,248
(22) Filed: Sep. 29, 2006
(65) Prior Publication Data
US 2007/0018871 Al Jan. 25, 2007
Related U.S. Application Data
A delta sigma modulator which employs a plurality of accumulators with non-power-of-2 modulus. The accumulators may consist of a primary non-power-of-2 modulus accumulator and a secondary non-power-of-2 modulus accumulator. The number of bits in the primary accumulators affects the frequency resolution of the resultant delta sigma fractional N frequency synthesizer and can be the minimum number of bits required by the resolution specification. The secondary accumulator integrates the carry outputs of its corresponding primary accumulators. This integration results in attenuating the dc content of the modulator output by a factor equal to the modulus of the secondary accumulators and may require compensation in the recombination block.
17 Claims, 5 Drawing Sheets