IEEE JOURNAL OF SOLID-STATE CIRCUITS, vol. 34, no. 4, page. 529 - 535, 1999-04
IEICE TRANSACTIONS ON ELECTRONICS, vol. E80C, no. 9, page. 1203 - 1210, 1997-09
IEEE JOURNAL OF SOLID-STATE CIRCUITS, vol. 32, no. 1, page. 79 - 85, 1997-01