A 13.5-MHz relaxation oscillator with ±0.5% temperature stability for RFID application

This paper presents a 13.5-MHz low-power, RC on-chip relaxation oscillator with split-capacitor technique for RFID application. This oscillator implements only one comparator and one reference voltage to minimize power consumption and silicon area. A loop delay variation cancellation technique that employs an integrator loop and a split-capacitor architecture helps attained the temperature stability in the proposed oscillator. The proposed design is fabricated in 0.18-μm CMOS process. The relaxation oscillator consumes 48.8 μW at 1.8-V power supply. The measurement results show that the circuit can generate a stable frequency of 13.5 MHz. The output frequency variation is less than ±0.5% of temperature range from -30° C to 120° C, and the supply voltage variation coefficient is 0.5%/V across 1.5 V to 2.1V supply voltage.