A Low Temperature Drift LC Oscillator

The current off-chip crystal oscillator has disadvantages such as large volume, high cost and difficult to integrate into the chip. An LC type oscillator with low temperature drift on chip is designed in this paper. The oscillator adopts Colpitts topology. The internal power supply circuit is used to supply power to other circuits to reduce the influence of the change of power supply voltage on the output frequency of the oscillator. The bias current of the Colpitts oscillator is Proportional to Absolute Temperature (PTAT), and the additional current compensation is made at high temperatures, so that the output amplitude of the oscillator remains stable at different temperatures. The bias voltage of the Colpitts oscillator is adjusted at different temperature points, which affects the parasitic capacitance of the transistor at different temperature, so that the output frequency of the oscillator has a low temperature drift. The simulation shows that the temperature coefficient of the output frequency is 1.1ppm/°C in the temperature range of -55~150°C at 1.8V power supply voltage. When the power supply voltage changes by ±10%, the power supply sensitivity of the output frequency is 23ppm/V, the phase noise is -121.7dBc/Hz@1MHz, and the power consumption is 2.89mW.