Design Of Integrated CMOS Temperature-compensated Quartz Crystal Oscillator

With the development of electronic technology,the application environment of electronic devices has become more and more complicated,especially the range of changes in the ambient temperature has getting larger and larger.As a frequency reference source for electronic systems,quartz crystal oscillators have been highly required for its temperature stability.At the earliest,People usually utilized a thermistor to compensate the temperature of the quartz crystal oscillator.However,due to the influence of technology,the thermistor compensation method is inferior in terms of volume,Power dissipation and accuracy.At present,there are mainly three strategies for quartz crystal oscillators to compensate the temperature including analog circuit temperature compensation,digital circuit temperature compensation,and microprocessor temperature compensation.By analyzing and comparing the advantages and disadvantages of the three temperature compensation methods,this paper will apply the analog circuit temperature compensation to study and design the quartz crystal oscillator.After careful analysis of the three-point oscillator's structure,this paper decides to choose the Santos structure.Firstly,the current distribution characteristic of the asymmetric differential pair is applied to realize the amplitude control to reduce the power consumption.Then inverter chain is expeeted to shape the rail-to-rail output.At that,a 12MHz automatic gain control crystal oscillator suitable for the wireless receiver chip is designed.The folded cascode structure is also used to design a bandgap reference voltage source circuit,which generates a temperature-dependent primary compensation voltage to realize a temperature detection circuit.Based on the differential pair method,a temperature compensation voltage generation circuit is designed,which is used to generate a temperature-dependent fifth power.The voltage compensates the oscillator circuit.The PMOS differential pair input structure is used to design a low-dropout linear regulator circuit to reduce the flicker noise of the circuit and,provide a stable bias for the system,finally complete the analog temperature compensation circuit design.Based on the HJ RF 0.18?m CMOS process,and the supply voltage is set VDD=3.3V,this paper complete the circuit module and overall circuit design.The results show that the temperature drift coefficient of the bandgap reference voltage source reaches 6.3ppm,the phase margin reaches 74.65°,the circuit noise is 371.6nV/sqrt(Hz),the power supply voltage rejection ratio can reach-95dB;when the load current is 500?A,and 30mA the phase margin of the LDO circuit is 65.70 and 94.87°,respectively,and the circuit can work stably in the voltage range of 1.55V?3.3V.At last,the layout design and post-simulation of the entire circuit is completed according to the design.In the range of-40? to 85?,the quartz crystal oscillator need 2.5ms to start up,and output of 12 MHz is stable,frequency fluctuation of is less than 71 ppm,phase noise is-121dBc/@1kHz,-165.1dBc/@1MHz.