【摘要】 本文介绍一种数字可编程射频锁相源的设计，及其在ＩＳ－９５标准的码分多址（ＣＤＭＡ）移动通信系统中的应用，它由电荷泵型的数字频率合成器，无源三阶环路滤波器，以及压控振荡器构成。作为ＣＤＭＡ移动通信系统本振源，为其提供射频上／下变频器和中频调制／解调器的本振信号、以及基带部分的参考基准信号，具有低相噪、低工作电压、低功耗的特点。文中还给出了使用ＬＭＸ２３３２Ａ／ＬＭ２３３７双环数字频率合成器研制的锁相振荡源的实例及其测试结果，其相位噪声在偏离载频１０ｋＨｚ处，均优于－９２ｄＢｃ。更多还原

【Abstract】 This paper presents the design of a digital programmable RF PLL local oscillator and its applications in CDMA mobile communication systems based on IS-95.The PLL oscillator is composed of two dual current mode charge pump synthesizer,such as LMX2337/LMX2332A,third order loop filter and VCO.It is employed for the local oscillator of RF mixer and IF modulator/demodulator,as well as the reference clock of baseband module in CDMA mobile system.It has the characteristic of low phase noise ,low power consumption and low operation voltage.Finally,experimental results show that the phase noise of all oscillators is less than -92dBc at 10kHz offset from carrier.更多还原