多通道升降沿产生激光驱动器超窄脉冲新方法

应用于不同领域的超窄脉冲激光驱动器要求输入脉冲宽度极窄,并且大范围内可调。传统的模拟器件可调性差难以满足要求,数字器件例如专用集成电路(ASIC)尽管脉冲宽度可以实现超窄输出,但是大范围内可调不易满足,并且存在可扩展性差,价格昂贵等特点,同样不利于推广。现场可编程门阵列(FPGA)程控性好,因此在脉冲激光驱动器中的数字脉冲源得到了很好的应用,但是传统的计数方法只能实现脉宽为时钟周期倍数的脉冲输出,因此只能应用于对窄脉宽要求不高的情形。为解决上述问题,本文基于FPGA设计了一种应用于超窄脉冲激光驱动器,在50 MHz时钟频率下利用锁相环倍频成多个通道的基准时钟,并分别利用上升下降沿计数器进行计数,再经不同逻辑运算输出的数字脉冲产生方法。最终的数字电路可以产生脉宽2~50 ns,步长1 ns可调,重复频率1 Hz~1 MHz的数字脉冲信号。最后分析了在高精度锁相环等硬件条件满足的情况下,该方法可以实现亚纳秒脉宽和步长的数字脉冲信号输出,因此具备了很好的可拓展性和前景。

Expert consensus on the diagnosis and treatment of solid tumors with BRAF mutations

The BRAF gene is an important signaling molecule in human cells that is involved in the regulation of cell growth,differentiation,and survival.When the BRAF gene mutates,it can lead to abnormal activation of the signaling pathway,which promotes cell proliferation,inhibits cell apoptosis,and ultimately contributes to the occurrence and development of cancer.BRAF mutations are widely present in various cancers,including malignant melanoma,thyroid cancer,colorectal cancer,non-small cell lung cancer,and hairy cell leukemia,among others.BRAF is an important target for the treatment of various solid tumors,and targeted combination therapies,represented by BRAF inhibitors,have become one of the main treatment modalities for a variety of BRAF-mutation-positive solid tumors.