用于SiC中子探测器的幅度脉冲调制电荷灵敏模拟前端电路设计

Design of an Amplitude-Pulse Modulated Charge-SensitiveAnalog Front End Circuit for SiC Neutron Detector

针对SiC沟槽型中子探测器输出的极其微弱的电流脉冲信号,设计了一款专用四通道读出集成电路。每个通道由高增益高带宽电荷灵敏放大器、高阶整形电路、峰值保持和时间检测电路组成,优化了电荷灵敏放大器(CSA)反馈回路,提高了增益线性度,避免了漏电流流入对基线的影响。电路能够快速响应输入信号,实现对能量和时间信息的提取。电路采用0.18μm CMOS工艺完成设计,实现了版图设计,后仿真结果表明,系统等效输入电荷范围为1.14 fC~22.35 fC,电荷转换增益为71.19 mV/fC,非线性误差在1.6%以内,等效噪声电荷为22 e^(-)。电路具有高增益高线性度的优点,能很好针对SiC沟槽型中子探测器输出电荷信号的特点,对其进行专用读出放大。

A four-channel readout application specific integrated circuit(ASIC)is developed in order to read the extremely weak output current pulse from SiC channel neutron detector.Each channel of the ASIC contains a charge-sensitive amplifier with high-gain and high-bandwidth,a high-order shaping circuit,and a peaking hold and time detection circuit.The proposed ASIC optimizes the CSA feedback loop,thus improving the gain linearity and avoiding the impact of leakage current inflow on the baseline.The circuit achieves the quick respond to the input signal and the extraction of energy and time information.The layout design of the AISC is based on the 0.18μm CMOS process.The post simulated results show that the equivalent input charge range of the system is 1.14 fC~22.35 fC.The charge con-version gain reaches 71.19 mV/fC.Moreover,the nonlinear error decreases to less than 1.6%and the equivalent noise charge is only 22 e^(-).The simulated results indicate that the ASIC has achieved high gain and high linearity.The ASIC can accurately reads out and am-plifies the neutron signal based on the characteristics of SiC channel neutron detector.