Maciej Borkowski Juha Kostamovaara Spurious tone free digital delta-sigma modulator design for DC inputs. 5601-5604 2005 conf/iscas/2005 ISCAS (6) http://dx.doi.org/10.1109/ISCAS.2005.1465907 db/conf/iscas/iscas2005-6.html#BorkowskiK05