A High Accuracy And Low Power Temperature Sensor

In the information age of increasing digital demand,high-stability frequency sources have become more and more important under the rapid development of electronic communication technology and market,and the frequency source generated by quartz crystal resonators has obvious advantages in stability.In engineering practice,it is found that when the temperature changes greatly,the accuracy of the frequency source of the electronic device is affected,which leads to equipment failure.This is because the resonant frequency of the quartz crystal resonator changes with temperature,which is called the frequency temperature characteristic.In order to eliminate the influence of large-scale changes in temperature on the accuracy of the frequency source,temperature compensation of the quartz crystal oscillator is required.Design a high-precision,low-power temperature sensor for temperature compensation of quartz crystal oscillators.The subject researched and designed a resistor-based CMOS temperature sensor with high resolution and low power consumption.The RC filter is used as the temperature sensing circuit.When the input signal is the resonant frequency of the filter,When the RC filter is driven at the resonant frequency of the filter,the change of temperature results in phase shift,and then the phase shift is digitized by a continuous-time phase-domain?-?modulation whose phase-summing node is realized by a chopper demodulator.Therefore,the RC filter is used as a temperature sensing circuit,The temperature sensing module of this design produces a total phase shift of 11°over the temperature range of-45°C to 85°C.Then the system error of the temperature sensing module circuit in the industrial temperature range is studied.The nonlinear error value of the phase shift is 0.035°C and the temperature error caused by the system resistance thermal noise is0.216°C.The outputs of the RC filter are demodulated by a chopper,the results of the chopper includes DC voltage which is associated with temperature.the continuous time phased?-?modulator has the characteristics of noise shaping and oversampling,effectively reducing the noise component in the low frequency region,and is quantized by the quantizer,the output of quantizer is serial single-byte bit stream which represents the temperature.Continuous-time phase-domain?-?modulator design includes two behavioral level simulations in MATLAB and Verilog-A.Firstly,the MATLAB completed the discrete-time noise transfer function design,modulator structure selection,non-ideal factor analysis,and its signal-to-noise ratio is 94.1dB.The conversion verification of discrete-time modulator to continuous-time modulation is then completed in Verilog-A with a signal-to-noise ratio of 89.8dB.The transistor-level circuit design was finalized,with a low-voltage bandgap reference design,a fully differential two-stage operational amplifier design,a constant transconductance amplifier design,and a comparator design.Implemented in TSMC 65nmlp CMOS technology,the maximum power consumption is only0.096mW under a supply voltage of 1.2V,and achieves 520?₈)resolution in a 5 ms conversion time.The sensor occupies an area of 1150?m?650?m.The temperature sensor is designed to be applied to the temperature compensation of the frequency reference.