Abstract: This paper presents a temperature compensated crystal oscillator (TCXO) chip with high accuracy and wide compensation temperature range, using SMIC 0.35μm standard CMOS process.The function generation circuit can generate voltage according with the five-ordered polynomial of crystal f-T characteristics, each part of the circuit can generate corresponding voltage of each term of the polynomial, and the adder circuit can adjust the coefficient of each term separately.The adjusting range of the circuit makes most a majority of AT cut crystals can be used in this design.The test results show that the frequency stability of TCXO can reach ±0.6ppm over the temperature range-40℃~105℃.