宽带直流放大器

针对小信号的幅度小、干扰大,线性放大难和提取难度大等问题,设计一种宽带直流放大器,是以单片机AT89C55WD和FPGA为控制核心,由可变增益放大器AD603为核心的放大电路、前级信号调理电路、后级功率放大电路和滤波电路组成。该放大器具有高增益且增益连续可调、输出波形无明显失真、有效抑制零点漂移和噪声、可输出大功率等特性．且在0-10MHz的频带内信号可放大0～75dB,带宽设置为5MHz或10MHz两种,输出信号峰峰值高达20V。     

宽带直流放大器

针对小信号的幅度小、干扰大,线性放大难和提取难度大等问题,设计一种宽带直流放大器.是以单片机AT89C55WD和FPGA为控制核心,由可变增益放大嚣AD603为核心的放大电路、前级信号调理电路、后级功率放大电路和滤波电路组成.该放大器具有高增益且增益连续可调、输出波形无明显失真、有效抑制零点漂移和噪声、可输出大功率等特性,且在0～10 MHz的频带内信号可放大0～75 dB,带宽设置为5 MHz或10 MHz两种,输出信号峰峰值高达20 V.     

体极化子的类相变行为

本文将电子的动量和位置的线性组合作为算符,应用了Bogolyubov不等式,并对哈密顿量进行两次么正变换,对电子-声子耦合常数α的整个区域和温度的尽可能广泛范围计算了体极化子的基态能量,有效质量及电子周围的平均声子数。发现对应一定的温度,当α超过一定值αc 时,极化子将发生相变。并且本文还找到了一个临界温度Tc ,当温度大于Tc 与温度小于Tc 时其相变行为是不同的。     

MAGNETIC PROPERTIES OF BALL MILLED FexCu1-x (x=0.4, 0.5) ALLOY

The samples Fe_0.4Cu_0.6 and Fe_0.5Cu_0.5 ball milled for 50 h are investigated by X-ray diffraction, M?ssbauer spectra, as well as magnetic measurement. The experiments show that the structure of the samples is fcc, with lattice constant 0.361 nm and there are fcc Fe-rich phase and fcc Cu-rich phase in the samples. Most of Fe atoms (91%) are in the fcc Fe-rich phase, which is a ferromagnetic phase. The M-H curve at 1.5 K shows the saturation magnetization of the samples are 80.5 emu/g and 101.6 emu/g for Fe_0.4Cu_0.6 and Fe_0.5Cu_0.5 respectively. The average magnetic moment of Fe atoms is deduced to be 2.40 μ_B . Compared with theoretical predication, the Fe atoms in the fcc phase are in high spin state.