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

Author

Zhang, Xin ; Pu, Yu ; Ishida, Koichi ; Ryu, Yoshikatsu ; Okuma, Yasuyuki ; Chen, Po-Hung ; Watanabe, Kazunori ; Sakurai, Takayasu ; Takamiya, Makoto

Author_Institution

Inst. of Ind. Sci., Univ. of Tokyo, Tokyo, Japan

Volume

59

Issue

6

fYear

2012

fDate

6/1/2012 12:00:00 AM

Firstpage

361

Lastpage

365

Abstract

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- μA 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 μA-10 mA output current range.

Keywords

CMOS integrated circuits; comparators (circuits); convertors; pulse modulation; switched capacitor networks; -digital VRF-PDM scheme; CMOS process; SC voltage converter; VRF-PDM; comparator; current 50 muA to 1 mA; efficiency 17 percent to 73 percent; efficiency 73 percent to 86 percent; hot-carrier injection; input switched-capacitor voltage converter; output voltage trimming; periodic activation scheme; voltage 0.45 V; voltage 1 V; voltage-reference-free pulse-density modulation; Clocks; Current measurement; Human computer interaction; Modulation; Switches; System-on-a-chip; Voltage measurement; Offset canceling; pulse-density modulation (PDM); switched capacitor (SC); voltage converter; voltage reference;

fLanguage

English

Journal_Title

Circuits and Systems II: Express Briefs, IEEE Transactions on

Publisher

ieee

ISSN

1549-7747

Type

jour

DOI

10.1109/TCSII.2012.2195056

Filename

6205614