多模式定位系统接收机中的分数频率综合器  

A Fractional-N Frequency Synthesizer for Multi-Mode Positioning System Receivers

作　　者：冯焱[1] 周海东[1] 忤婷[1] 申佳[1] 陈贵灿[1] 

机构地区：[1]西安交通大学电子与信息工程学院,西安710049

出　　处：《西安交通大学学报》2011年第8期85-91,107,共8页Journal of Xi'an Jiaotong University

摘　　要：针对单一的全球定位系统中接收性能易受环境影响的问题，提出了一个应用于3个定位系统、7种模式的多模式定位接收机中的分数频率综合器．通过改进的电流泵电流校正方法和提高谐振回路Q值等各种降低相位噪声的方法，达到了每种模式工作的稳定性和低相位噪声性能；以改进的多模分频器和3阶MASHl—1一l∑一△调制器实现了7个频点的精确输出和各模式的快速锁定；在多模分频器中使用简单的电路将分频比的范围从64~79扩展到64~95．仿真结果表明，在每种模式下带内相位噪声（相对于载波的相噪声）均小于一90dB，带外频偏1MHz处相位噪声均小于一119dB，杂散抑制（相对载波）均大于56．4dB，各个模式锁定时间均小于18扯s，1．8V电源条件下的功耗为15．12mW．A ffactional-N frequency synthesizer that is applied in multi-mode positioning receiver for seven modes in three positioning systems is presented in order to solve the problem that the receive performance is sensitive to the environment in a single GPS. All of the seven modes can work stably and achieve lower phase noise performance by improving the method to adjust the programmable charge pump current, and by raising the value of Q factor in tank to reduce phase noise. The fast lock-in and accurate output frequencies of all modes are realized by using improved multi-mode divider and MASHI-I-1 modulator. A simple circuit is proposed to expand divide range from 64-79 to 64-95 in the multi-modulus divider. Simulation results show that the synthesizer meets the requirements of seven modes. The performance of each mode is as follows, the in-band and out-of-band phase noises （with respect to carrier） are not larger than -90 dB and-119 dB at 1 MHz offsets, respectively. The reference spurs （with respect to carrier） are less than- 56.4 dB, and the lock-in time is less than 18 μs. The total power consumption is 15.12 mW at 1.8 V voltage supply.

关 键 词：全球定位系统 分数频率综合器 多模式 相位噪声 

分 类 号：TN432[电子电信—微电子学与固体电子学]