用于GEM探测器的高集成度专用集成电路研制

Gas Electron Multiplier (GEM) is a new gas detector developed in the past few years. Because of its good position resolution, radiation hardness and fast response, GEM is widely used in particle physics experiments, astrophysics, medical imaging and synchrotron radiation. In order to achieve better position resolution, the pitch of the readout strips is about hundred microns or even smaller. This makes the GEM detector's readout electronics to deal with hundreds or even thousands of channels, highly integrated ASIC must be used to meet the strigent demands of the readout signal density, noise, power and many other aspects. This project is to develop a highly integrated, fully functional readout ASIC for GEM detector. Each channel consists of charge sensitive preamplifier, shaper, peak detect and hold circuits, discriminator, analog to digital converter (ADC) and some other blocks. The signal amplification, shaping, peak holding, analog to digital converting and other series of functions are all done automatically inside the chip. The analog to digital conversion results can be sent directly to the FPGA for processing which will greatly improve the integration and reliability of the equipment, and makes GEM detector readout electronics system more concise.

气体电子倍增器（GEM）是近年来出现的新型气体探测器，因为具有位置分辨好、抗辐照性能强、响应速度快等特点，在粒子物理实验、天体物理、医学成像、同步辐射成像等领域，具有广泛的应用前景。为实现高位置分辨率，GEM探测器相邻两个读出条的中心距一般设计为几百个微米或更小，这就使得GEM探测器读出电子学需要处理的信号通道数量在数百甚至数千个通道之间，必须采用高集成度的专用集成电路才能满足在读出信号密度、噪声、功耗等多方面的苛刻要求。本项目就是为了研制一款高集成度、全功能的用于GEM探测器信号读出的专用集成电路。单个通道集成了电荷灵敏前置放大器、滤波成形电路、峰值保持电路、甄别电路、模数转换器等模块，对信号的放大、成形、峰值保持和模数变换等一系列功能全部在芯片内部自动完成，A/D变换的结果可直接送到FPGA中进行处理，这无疑将大大提升设备的集成度和可靠程度，使读出电子学系统的设计更简洁。

气体电子倍增器（GEM）具有位置分辨好、抗辐照性能强、响应速度快等特点，在粒子物理实验、天体物理、医学成像、同步辐射成像等领域，具有广泛的应用前景。为实现高位置分辨率，GEM 探测器相邻两个读出条的中心距一般设计为几百个微米或更小，这就使得GEM 探测器读出电子学通道数急剧增加。针对GEM探测器的读出需求，本课题开展前端多通道读出专用集成电路（ASIC）的研究。芯片集成32 通道，实现了单道内电荷灵敏前置放大、滤波成形、峰值保持、甄别电路、模数转换器（ADC)等模块，对信号的放大、成形、峰值保持和模数变换等一系列功能全部在芯片内部自动完成。通过对芯片的测试，该芯片能够工作正常，其中积分非线性好于1%，零电容等效输入噪声电荷数约为500e-。研究设计了通道内集成10bit SAR-ADC，该ADC具有结构简单、功耗低、体积小等特点，利于通道内集成。分别对ADC 模块进行流片测试，实测结果显示，ADC 模块在1.250Msps 采样率下其有效位（ENOB）好于9.2。