A High Frequency Accuracy, High Stability and Tunable RC Oscillator

This paper presents a tunable RC oscillator with high frequency accuracy and high stability. By using a new topology of adding two switches, the oscillation frequency is independent of the capacitor discharge time. At the same time, this paper proposes a new type of DAC resistor array for the DAC current reference trimming module, which uses a parallel resistor array temperature compensation design with a positive and negative temperature coefficient and an architecture design to cancel the switch resistance, which greatly reduces the influence of temperature and the on-resistance of the switch on the oscillator. The simulation results show that under the different process corners of TT, SS and FF, a stable 2MHz square wave signal is obtained in a wide power supply voltage range (2.7~5.5V) and a wide temperature range (-40~125℃). The frequency variation affected by the power supply voltage is 0.295%, 0.312% and 0.337%, respectively. The frequency variation affected by temperature is 0.997%, 0.968% and 0.989%, respectively. And the dutycycle of the clock output signal is within 49.6%~50.3%.