[1] Natl Univ Singapore, Dept Elect & Comp Engn, Singapore, Singapore
[2] Natl Cheng Kung Univ, Mixed Signal Integrated Circuit Lab, Tainan, Taiwan
[3] Maxim Integrated, Adv R&D, North Chelmsford, MA 01863 USA
[4] Columbia Univ, Dept Elect Engn, New York, NY 10027 USA
[5] Oregon State Univ, Sch Elect Engineeering & Comp Sci, Corvallis, OR 97330 USA