A wideband low power low phase noise dual-modulus prescaler

This paper describes a novel divide-by-32/33 dual-modulus prescaler(DMP).Here,a new combination of DFF has been introduced in the DMP.By means of the cooperation and coordination among three types,DFF, SCL,TPSC,and CMOS static flip-flop,the DMP demonstrates high speed,wideband,and low power consumption with low phase noise.The chip has been fabricated in a 0.18-μm CMOS process of SMIC.The measured results show that the DMP’s operating frequency is from 0.9 to 3.4 GHz with a maximum power consumption of 2.51 mW under a 1.8 V power supply and the phase noise is -134.78 dBc/Hz at 1 MHz offset from the 3.4 GHz carrier.The core area of the die without PAD is 57×30μm~2.Due to its excellent performance,the DMP could be applied to a PLL-based frequency synthesizer for many RF systems,especially for multi-standard radio applications.     

基于级联式偏置锁相环的低相噪宽带频率合成器*

为提高锁相环的相位噪声性能,本文设计了一种级联式偏置锁相环来实现宽带低相噪频率合成器,通过理论分析得到其相位噪声模型,证明了该技术能够有效地降低锁相环路中鉴相器的噪声基底,并且混频交互调产生的所有杂散可由环路滤波器抑制,从而将窄带高频谱纯度信号扩展为宽带高频谱纯度信号。基于该技术提出了2GHz ~5GHz 的低相噪宽带频率合成器方案,并对其相位噪声指标进行了分析。理论与实验结果表明,相比于传统的小数分频式锁相环方案,该方案的带内相位噪声有明显改善。     

面向应用型人才的“单片机”课程教学改革

本文针对"单片机"课程教学中存在的问题,提出了敏捷开发和CDIO理念相结合的该课程教学新方法:教师精心设计实践项目,运用敏捷开发和CDIO理念,按照企业产品生产管理标准组织教学。通过与企业项目开发流程对比发现,该方法与其基本一致,教学效果明显提高。     

一种宽带Chirp-DDS及其FPGA实现

设计了一种宽带Chirp-DDS，并在Altera Flex 10K FPGA上予以实现。该结构包括32位流水线频率．相位累加器和ROM查找表。系统的时钟频率为100MHz，频率切换时间为0.68ps，建立时间为0．8μs，频率分辨率为0．02328 Hz，输出信号的频率范围为DC到40 MHz。     

一种基于0.35m工艺的高速混合旋转结构DDFS

设计实现了一种基于CORDIC算法和乘法器的直接数字频率合成器。采用混合旋转算法实现相位幅度转换,最高工作频率达到400MHz。在算法级,将DDFS中需要执行的π/4旋转操作分成两次旋转完成,第一次旋转采用CORDIC算法,第二次旋转采用乘法器来完成,同时采用流水线结构来实现累加器,提高整体性能。在晶体管级,采用DPL(Double-pass-transistor logic)逻辑实现基本电路单元,减少延迟提高速度。经0.35μmCMOS工艺流片,在400MHz的工作频率下,输出信号在80MHz处,SFDR为76.47dB,整个芯片面积为3.4mm×3.8mm。     

锁相式频率合成器相位噪声分析与仿真

相位噪声是影响频率合成器性能的重要指标,首先分析了锁相式频率合成器各个组成部分的相位噪声,然后根据相位噪声传输函数,建立了频率合成器相位噪声的精确仿真预测模型.为了验证仿真方法的可靠性,设计了一个输出频率为2GHz的频率源,实验测得的相位噪声曲线和仿真结果非常吻合.     

频率合成器的相位噪声分析

频率合成器被喻为雷达电子系统的"心脏",其相位噪声对设备和系统的性能影响很大.文中简单介绍了频率合成器相位噪声的基本概念.基于频率合成器的基本实现方法,分析了频率合成器中的相位噪声,通过实例说明了不同合成方式频率合成器的相位噪声.时频率合成器的低相噪声设计的工程实现有一定的指导意义.     

具有工艺补偿和毛刺消除功能的快速锁定频率预置锁相环频率综合器

This paper proposes a fast-settling frequency-presetting PLL frequency synthesizer. A mixedsignal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time. An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current. The digital processor can automatically compensate presetting frequency variation with process and temperature, and control the operation of the auxiliary tuning loop. A 1.2 GHz integer-N synthesizer with 1 MHz reference input was implemented in a 0.18 μm process. The measured results demonstrate that the typical settling time of the synthesizer is less than 3 μs, and the phase noise is –108 dBc/Hz@1MHz. The reference spur is –52 dBc.     

A fast-settling frequency-presetting PLL frequency synthesizer with process variation compensation and spur reduction

This paper proposes a fast-settling frequency-presetting PLL frequency synthesizer.A mixed-signal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time.An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current.The digital processor can automatically compensate presetting frequency variation with process and temperature,and control the operation of the auxiliary tuning loop.A 1.2 GHz integer-N synthesizer with 1 MHz reference input Was implemented in a 0.18μm process.The measured results demonstrate that the typical settling time of the synthesizer is less than 3μs,and the phase noise is-108 dBc/Hz@1MHz.The reference spur is-52 dBc.     

DDS相位舍位杂散信号的频谱分析

杂散特性限制着直接数字频率合成（DDS）技术的应用和发展,其中相位舍位、幅度量化和DAC的非理想特性等是影响DDS输出频谱质量的主要杂散源。文中主要研究相位舍位对DDS输出频谱的影响,首先通过离散傅里叶变换将任意的频率控制字转化为频率控制字为1来对DDS的输出信号进行频谱分析,然后由DDS的输出序列入手深入研究了相位舍位时DDS输出频谱的特性,得到的DDS输出频谱的数学模型精确、简单。