一种用于射频调谐器的低相位噪声低功耗晶体振荡器(英文)

实现了一种基于CMOS工艺的用于DRM与DAB数字广播射频调谐器的具有低相位噪声与低功耗的工作在37.5MHz的差分结构晶体振荡器.在晶体振荡器的核心部分采用了PMOS晶体管来代替传统的NMOS晶体管以降低相位噪声.采用了对称结构的电流镜以提高直流稳定度.采用了由一阶CMOS运算跨导放大器和简单的幅度探测器构成的幅度探测电路以提高输出信号的电流精确度.芯片采用0.18-μmCMOS工艺实现,芯片面积为0.35mm×0.3mm.芯片包含用于驱动50Ω测试的负载接口电路,在1.8V供电电压下,所测得的芯片功耗仅为3.6mW.晶体振荡器的工作输出信号在距离其中心频率37.5MHz频偏1kHz处的相位噪声为-134.7dBc/Hz.

A low-phase-noise and low-power crystal oscillator for RF tuner

A 37.5 MHz differential complementary metal oxide semiconductor (CMOS) crystal oscillator with low power and low phase noise for the radio frequency tuner of digital radio broadcasting digital radio mondiale (DRM) and digital audio broadcasting (DAB) systems is realized and characterized.The conventional cross-coupled n-type metal oxide semiconductor (NMOS) transistors are replaced by p-type metal oxide semiconductor (PMOS) transistors to decrease the phase noise in the core part of the crystal oscillator.A symmetry structure of the current mirror is adopted to increase the stability of direct current.The amplitude detecting circuit made up of a single-stage CMOS operational transconductance amplifier (OTA) and a simple amplitude detector is used to improve the current accuracy of the output signals.The chip is fabricated in a 0.18-μm CMOS process,and the total chip size is 0.35 mm×0.3 mm.Under a supply voltage of 1.8 V,the measured power consumption is 3.6 mW including the output buffer for 50 Ω testing loads.The proposed crystal oscillator exhibits a low phase noise of-134.7dBc/Hz at 1-kHz offset from the center frequency of 37.5 MHz.