GSM/EDGE射频芯片内数控晶体振荡器的设计

Design of Digitally-Controlled Crystal Oscillator for GSM/EDGE Radio-Frequency Integrated Chip

运用等效小信号模型分析石英晶体振荡器,设计实现了一种适用于GSM/EDGE手持式射频收发芯片的数控晶体振荡器(DCXO).该振荡器采用Colpitts结构,利用自动增益负反馈控制电路幅度,并利用数控电容阵列来调整瞬态频率稳定度.电路采用TSMC0.18μm CMOS工艺实现,中心频率为26 MHz.在1.8 V电源电压下的仿真结果显示:数控范围为123×10-6@26 MHz,调节精度为0.0075×10-6/步,启动时间约为1.5 ms,振荡峰峰值约为1.2 V;在偏离中心频率1 kHz和10 kHz处的相位噪声分别为-145.800和-153.032dBc/Hz;整个电路功耗仅为3mW.

By analyzing the quartz crystal oscillator with the equivalent small-signal model,a digitally-controlled crystal oscillator（DCXO） for GSM/EDGE RF transceiver chips is designed and implemented.DCXO,in Colpitts structure,uses the automatic-gain negative feedback to control the circuit amplitude and adopts a digitally-controlled capacitor array to adjust the stability of transient frequency.The whole circuit is implemented via the TSMC 0.18μm CMOS technology,with a center frequency of 26MHz.Simulated results in the case of 1.8V power supply show that（1） DCXO is of a digitally-controlled range of 123×10-6@26MHz,a regulation accuracy of 0.0075×10-6 per step,a startup time of about 1.5ms and an oscillation peak of about 1.2V;（2） the phase noises respectively reach-145.800dBc/Hz at 1kHz and-153.032dBc/Hz at 10kHz offset;and（3） the total power consumption of DCXO is only 3 mW.