In this paper, a nanosecond voltage comparator with PECL logic for a photon-counting radiation imaging system is presented. To realize a high-speed comparison of four gamma detector channels in a limited board space, quad comparators MAX9602 with PECL logic are chosen. Each of the four channels is coupled with a PECL to CMOS converter ICS508, which exports CMOS logic data for later use in an FPGA. Simulated findings for cobalt-60 with intensities ranging from 30 Ci to 300 Ci show little count loss caused by using a comparator and indicate ideal propagation delays at all source intensities. While in the laboratory test using a PCB-level system, signals with pulse width less than 3 ns might be dropped, and dispersion of propagation delay occurs. Despite these, the performance is still satisfactory and can meet the requirements of practical applications, as demonstrated by an improved result of 0.9% in the contrast indicator model. Further studies to optimize the circuit design can be conducted to gain improvement.

中文翻译：

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用于光子计数辐射成像系统应用的具有 PE​​CL 逻辑的纳秒电压比较器的设计

本文提出了一种用于光子计数辐射成像系统的具有 PE​​CL 逻辑的纳秒电压比较器。为了在有限的电路板空间内实现四个伽马检测器通道的高速比较，选择了具有PECL逻辑的四比较器MAX9602。四个通道中的每一个都与 PECL 至 CMOS 转换器 ICS508 耦合，该转换器导出 CMOS 逻辑数据以供稍后在 FPGA 中使用。对强度范围为 30 Ci 至 300 Ci 的钴 60 进行的模拟结果显示，使用比较器导致的计数损失很小，并表明在所有源强度下都有理想的传播延迟。在使用PCB级系统的实验室测试中，脉冲宽度小于3 ns的信号可能会被丢弃，并且会出现传播延迟的分散。尽管有这些，性能仍然令人满意，可以满足实际应用的要求，对比指标模型的结果提高了0.9%。可以进行进一步的研究来优化电路设计以获得改进。