提出了一种新型的基于相位噪声抵消技术的频率合成器设计方法,该方法采用一个相参的锁相环信号在两次频率变换过程中得到输出信号相位噪声的抵消。对相位噪声抵消技术进行了理论分析,并搭建了一个100~2900 MHz宽带小步进频率源。实验结...提出了一种新型的基于相位噪声抵消技术的频率合成器设计方法,该方法采用一个相参的锁相环信号在两次频率变换过程中得到输出信号相位噪声的抵消。对相位噪声抵消技术进行了理论分析,并搭建了一个100~2900 MHz宽带小步进频率源。实验结果表明,在偏离主频10 k Hz、100 k Hz处,相位噪声抵消了约20 d B,实验证明该技术对中近区相位噪声抵消效果明显,为超低相噪频率合成器设计提供了一种新的思路。展开更多
本文提出了适用于医学领域的R-MOSFET-C滤波器,采用MOSFET代替传统RC有源滤波器中的电阻,实现可调、超低截止频率。该滤波器采用UMC 0.13 m CMOS工艺,电源电压为1.2V。仿真结果显示,当外部可调电压,即MOSFET的栅电压在0.6V到0.84V之间...本文提出了适用于医学领域的R-MOSFET-C滤波器,采用MOSFET代替传统RC有源滤波器中的电阻,实现可调、超低截止频率。该滤波器采用UMC 0.13 m CMOS工艺,电源电压为1.2V。仿真结果显示,当外部可调电压,即MOSFET的栅电压在0.6V到0.84V之间变化时,截止频率可随之在0.2Hz到292.8Hz之间变化。展开更多
The RF system for the Beijing Electron Positron Collider Upgrade(BEPCⅡ)Project had been working since Nov,2006.It consists of 3 subsystems including the superconducting cavity,the klystron and the low level RF system...The RF system for the Beijing Electron Positron Collider Upgrade(BEPCⅡ)Project had been working since Nov,2006.It consists of 3 subsystems including the superconducting cavity,the klystron and the low level RF system.Compared with the former RF system,the operating frequency has been changed from 200MHz to 499.8MHz, and the superconducting cavity has been used to replace the normal cavity.Up to now,the RF system performance is good and achieves the designed target.展开更多
Objective: To investigate the effects of low-intensity pulsed ultrasound in repairing injured articular cartilage. Methods: Ten adult New Zealand rabbits with bilateral full-thickness osteochondral defects on the cart...Objective: To investigate the effects of low-intensity pulsed ultrasound in repairing injured articular cartilage. Methods: Ten adult New Zealand rabbits with bilateral full-thickness osteochondral defects on the cartilage surface of intercondylar fossas were used in this study. The wounds in the left knees were treated with low-intensity pulsed ultrasound as the experimental group. The right knees received no treatment as the control group. All the animals were killed at 8 weeks after injury and the tissues in the wounds were collected for gross appearance grading, histological grading and proteoglycan quantity. Results: The scores of the gross appearance grades, histological grades and the optical density of toluidine blue of the tissues in the experimental group were significantly higher than those of the controls at 8 weeks after injury (P<(0.05)). Conclusions: Low-intensity pulsed ultrasound can accelerate the repair of injured articular cartilage.展开更多
文摘提出了一种新型的基于相位噪声抵消技术的频率合成器设计方法,该方法采用一个相参的锁相环信号在两次频率变换过程中得到输出信号相位噪声的抵消。对相位噪声抵消技术进行了理论分析,并搭建了一个100~2900 MHz宽带小步进频率源。实验结果表明,在偏离主频10 k Hz、100 k Hz处,相位噪声抵消了约20 d B,实验证明该技术对中近区相位噪声抵消效果明显,为超低相噪频率合成器设计提供了一种新的思路。
文摘本文提出了适用于医学领域的R-MOSFET-C滤波器,采用MOSFET代替传统RC有源滤波器中的电阻,实现可调、超低截止频率。该滤波器采用UMC 0.13 m CMOS工艺,电源电压为1.2V。仿真结果显示,当外部可调电压,即MOSFET的栅电压在0.6V到0.84V之间变化时,截止频率可随之在0.2Hz到292.8Hz之间变化。
文摘The RF system for the Beijing Electron Positron Collider Upgrade(BEPCⅡ)Project had been working since Nov,2006.It consists of 3 subsystems including the superconducting cavity,the klystron and the low level RF system.Compared with the former RF system,the operating frequency has been changed from 200MHz to 499.8MHz, and the superconducting cavity has been used to replace the normal cavity.Up to now,the RF system performance is good and achieves the designed target.
文摘Objective: To investigate the effects of low-intensity pulsed ultrasound in repairing injured articular cartilage. Methods: Ten adult New Zealand rabbits with bilateral full-thickness osteochondral defects on the cartilage surface of intercondylar fossas were used in this study. The wounds in the left knees were treated with low-intensity pulsed ultrasound as the experimental group. The right knees received no treatment as the control group. All the animals were killed at 8 weeks after injury and the tissues in the wounds were collected for gross appearance grading, histological grading and proteoglycan quantity. Results: The scores of the gross appearance grades, histological grades and the optical density of toluidine blue of the tissues in the experimental group were significantly higher than those of the controls at 8 weeks after injury (P<(0.05)). Conclusions: Low-intensity pulsed ultrasound can accelerate the repair of injured articular cartilage.
