A Sub-1-µs Start-Up Time, Fully-Integrated 32-MHz Relaxation Oscillator for Low-Power Intermittent Systems

Hiroki ASANO  Tetsuya HIROSE  Taro MIYOSHI  Keishi TSUBAKI  Toshihiro OZAKI  Nobutaka KUROKI  Masahiro NUMA  

IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.3   pp.161-169
Publication Date: 2018/03/01
Online ISSN: 1745-1353
Type of Manuscript: PAPER
Category: Electronic Circuits
relaxation oscillator,  fast start-up,  digital signal processing,  high accuracy,  intermittent operation,  PVT variations,  

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This paper presents a fully integrated 32-MHz relaxation oscillator (ROSC) capable of sub-1-µs start-up time operation for low-power intermittent VLSI systems. The proposed ROSC employs current mode architecture that is different from conventional voltage mode architecture. This enables compact and fast switching speed to be achieved. By designing transistor sizes equally between one in a bias circuit and another in a voltage to current converter, the effect of process variation can be minimized. A prototype chip in a 0.18-µm CMOS demonstrated that the ROSC generates a stable clock frequency of 32.6 MHz within 1-µs start-up time. Measured line regulation and temperature coefficient were ±0.69% and ±0.38%, respectively.