Improved CMOS ring oscillator with stable frequency

LV Jieru, QIN Huibin, HUANG Haiyun
(College of Electronic and Information, Hangzhou Dianzi Universty, Hangzhou 310018, China)

Abstract: 1.2 MHz CMOS ring oscillator operates under voltage range 3 V～6 V and temperature range -40 ℃～85 ℃ was presented. This oscillator circuit was designed with Candence software, and was fabricated in the standard 0.5 μm doublepoly, triple metal CMOS process of Wuxi CSMC. Aiming at the problem of oscillation frequency changes with the power supply voltage, a modified ring oscillator was presented, based on the analysis of the traditional ring oscillator. Then the corresponding relation of power supply voltage and oscillation frequency was received through circuit simulation and analysis by using Candence software. The results indicate that output frequency vary ±5% from the nominal frequency in the whole power supply voltage range 3 V～6 V.
Key words: CMOS IC; oscillator; ring oscillator