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一种用于MRPC前端读出的原型ASIC设计

Design of a Prototype ASIC for the MRPC Front-end Readout

  • 摘要: 飞行时间(TOF)探测器是核与粒子物理实验的重要组成部分,多气隙电阻板室(MRPC)以其高时间精度的特点在TOF测量系统中被广泛应用,放大甄别结合时间数字变(TDC)换是MRPC电子学读出的一种主流方案。为了满足MRPC读出电子学高时间精度、低功耗、高集成度的需求,设计了一款高速放大甄别原型芯片,该芯片集成了8个通道,通道内包含前置放大器、甄别器和输出驱动电路。前置放大器采用共栅极结构,这种低输入阻抗的结构有利于进行阻抗匹配设计;甄别器采用多级放大器级联的结构产生足够的增益,通过对信号进行饱和放大实现甄别功能;经过甄别后的脉冲波形信号由低压差分信号(LVDS)输出驱动器送到片外,其前沿和脉宽分别可以表征MRPC信号的到达时间(TOA)和电荷量信息。基于180 nm工艺完成了电路的设计、仿真和流片,并在实验室环境下完成了电子学性能测试。测试结果表明,在100 fC~2 pC电荷量下,该芯片的时间精度好于10 ps(rms),单通道功耗约为24 mW。

     

    Abstract: The time of flight (TOF) detector is an important component of nuclear and particle physics experiments, and multi-gap resistive plate chamber (MRPC) is widely used in TOF measurement systems due to its high time precision. The mainstream technique for the readout of the MRPC detector involves amplification and discrimination, combined with a time-to-digital converter (TDC). To meet the requirements of high time precision, low power consumption, and high integration in MRPC readout electronics, a high-speed amplification and discrimination prototype chip has been designed. The chip integrates 8 channels, each of which includes a preamplifier, a discriminator, and an output driver circuit. The preamplifier adopts a common gate structure, facilitating impedance matching with low input impedance. The discriminator uses multiple cascaded amplifiers to provide enough gain, and achieves discrimination function by saturating amplification. After discrimination, the pulse signal is conveyed outside the chip via a low-voltage differential signaling (LVDS) driver, and its front edge and pulse width can characterize the time of arrival (TOA) and charge information of the MRPC signal. Based on 180 nm CMOS process, the circuit design, simulation and fabrication have been completed, and the performance test has been conducted in the laboratory environment. The test results indicate that the time precision is better than 10 ps (rms) with 100 fC~2 pC injected charge and the single channel power consumption is approximately 24 mW.

     

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