A 1-V-Input Switched-Capacitor Voltage Converter With Voltage-Reference-Free Pulse-Density Modulation

作者：Zhang Xin^*; Pu Yu; Ishida Koichi; Ryu Yoshikatsu; Okuma Yasuyuki; Chen Po Hung; Watanabe Kazunori; Sakurai Takayasu; Takamiya Makoto

来源：IEEE Transactions on Circuits and Systems II-Express Briefs, 2012, 59(6): 361-365.

DOI：10.1109/TCSII.2012.2195056

• Offset canceling
• pulse-density modulation (PDM)
• switched capacitor (SC)
• voltage converter
• voltage reference

A 1-V-input 0.45-V-output switched-capacitor (SC) voltage converter with voltage-reference-free pulse-density modulation (VRF-PDM) is proposed. The all-digital VRF-PDM scheme improves the efficiency from 17% to 73% at 50-mu A output current by reducing the pulse density and eliminating the voltage reference circuit. An output voltage trimming by the hot-carrier injection to a comparator and a periodic activation scheme of the SC voltage converter are also proposed to solve the problems attributed to VRF-PDM. The proposed voltage converter is fabricated in 65-nm CMOS and achieves an efficiency value of 73%-86% at 50 mu A-10 mA output current range.

• 出版日期2012-6