A 24MHz Relaxation Oscillator Using Single Current Mode Comparator with ±1.67% Drift from -40°C to +175°C for Automotive Sensor Application

This paper presents a 24MHz RC on-chip relaxation oscillator with single current mode comparator for automotive sensor application. This oscillator implements only one high speed comparator operating in current mode and a local reference voltage to control the charging process. The frequency trimming is executed at room temperature to constrain process and mismatch impacts. Duty cycle deviation is attenuated as low as possible since identical hardware is reused between current and following period. The power supply rejection (PSR) is improved by a local regulator and a RC filter separately. The proposed design is fabricated in 0.18-μm CMOS technology. The oscillator analog core consumes 100μA at 3.3V power supply. The measurement results show that a stable output frequency is created as 24MHz after trimming with ±1.67% deviation from -40°C to 175°C. The supply voltage ranges from 1.8V to 3.6V.