Abstract: A low power CMOS bandgap voltage reference circuit used in the temperature compensated crystal oscillator (TCXO) has been designed using CSMC 0.35 μm mixed process.The voltage transform circuit at the output stage is used as a buffer to provide various tunable reference voltages.The start-up circuit and the logic control circuit have also been designed, ensuring the proper function and power reduction of the reference circuit.Simulation results using Cadence Spectre indicate that at a supply voltage of 3 V, the average measured temperature coefficient is 14.5 ppm/℃ in the temperature range of-40℃ to 85℃.The circuit can be started up at a supply voltage greater than 2.2 V.Under normal working conditions, the power dissipation is less than 10 μW and the power supply rejection ratio is about 83.2 dB.