Wide band low phase noise QVCO based on superharmonic injection locking

A wide band, injection-coupled LC quadrature voltage control oscillator is presented. In the proposed circuit, two oscillators are injection locked by coupling their second-order harmonics in anti-phase, forcing the outputs of two oscillators into a quadrature phase state. As the common-mode point sampling the second harmonic frequency, flicker noise of the tail current is suppressed, the phase noise is reduced.The proposed design accomplishes a wide tuning frequency range by a combination of using a 5-bit switch capacitor array (SCA) for discrete tuning in addition to linearly varying AMOS varactors for continuous tuning. The proposed design has been fabricated and verified in a 0.18 μ m TSMC CMOS technology process. The measurement indicates that the quadrature voltage controlled oscillator has a 41.7% tuning range from 3.53 to 5.39 GHz. The measured phase noise is 127.98 dBc/Hz at 1 MHz offset at a 1.8 V supply voltage with a power consumption of 12 mW at a carrier frequency of 4.85 GHz.     

液-液界面法制备的Cu2O/GO复合材料及其光催化性能研究

采用液-液界面反应法制备了氧化亚铜/氧化石墨烯复合材料(Cu_2O/GO),采用X射线衍射分析仪、扫描电子显微镜对材料的物相和形貌进行表征,研究了其对亚甲基蓝(MB)的光催化降解效果。结果表明,利用液-液界面法制备的Cu_2O/GO材料中的Cu_2O呈多面体晶型结构,且均匀地分布在薄层氧化石墨烯两侧。在室温条件下,MB初始浓度为40mg·L~(-1),催化剂投加量为0.03g,降解时间为50min,溶液pH=7时,MB的降解率可达95%。     

基于GSM的无人值守停车场管理系统设计

介绍一种无人值守的停车场管理系统的设计。该系统前端主要由GSM短信模块TC35i和AVR单片机Atmega16组成,安装在停车场的每个进出口,通过接收车主的手机短信控制进出口道闸的开启并由短信扣取停车费用,各进出口电路都与监控中心计算机连接。该系统联网后还可以进行短信查询及预定车位。通过采用该系统可以取代现有的取卡和现金收费的停车场管理办法,从而实现停车场的无人值守。     

基于超谐波注入锁定的低相噪QVCO的设计

对基于注入锁定的正交压控振荡器(QVCO)电路进行了研究和分析,设计了一个低相位噪声、低相位误差的QVCO电路,该电路由两个电感电容压控振荡器(LC VCO)在正交相位进行超谐波耦合,通过一个频率倍增器在交叉耦合对的共模信号点注入同步信号.通过对相位误差公式的推导,提出了降低相位误差的方法,由于该电路在共模点采用二倍频取样,抑制了尾电流的闪烁噪声,降低了相位噪声.电路基于TSMC 0.18 μm互补金属氧化物半导体(CMOS)工艺实现,测试结果表明,当谐振频率从4.5 GHz调谐到4.9 GHz时,在电源电压为1.8V时,电路消耗功率为13 mW,1 MHz频偏处的单边带(SSB)相位噪声为-129.95 dBc/Hz,与传统的QVCO相比,噪声性能得到了改善.