A 36MHz Relaxation Oscillator with±0.2% Temperature Variation for MCU Application

This paper presents an on-chip 36MHz high precision relaxation oscillator with voltage averaging feedback for MCU (microcontroller unit) applications. The proposed design is fabricated in 0.11-um CMOS process, the relaxation oscillator consumes 78uA. The frequency variation with supply voltage is reduced by a internal LDO(low dropout regulator) circuit, with a wide input range of I.S-5V, the measured frequency variation with supply voltage is within ±0.02%. The measured frequency variations is ±0.2% over a temperature range of −45°C-105°C. It has low temperature shift characteristics in the oscillation frequency range, which is very suitable for MCU’s requirements for multi-system clock frequency.