High Precision RC Relaxation Oscillator for Wide Supply Voltage Swing from 2.5V to 5.5V

A low-temperature drift current-mode relaxation oscillator suitable for wide supply voltage swing is presented. The characteristic that the delay of the buffer is proportional to the supply voltage and inversely proportional to the bias current is exploited. The bias of the buffer is provided by the current source that changes with the supply voltage, so as to achieve the purpose that the delay of the buffer is weakly correlated with the supply voltage and suppress the change of the output frequency. A temperature-dependent resistance is used to balance the delay of the buffer with temperature. The experimental results show that the typical frequency of the oscillator is 2MHz. The frequency variation is 0.33%/V for the supply voltage of 2. 5~5.5V and 40.6ppm/°C for temperature of −40~125°C.