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为了解决像素碲锌镉探测器的高密度和低噪声读出问题,设计了一款8通道的低噪声前端读出芯片。每个通道由两级电荷灵敏前放、4阶半Gauss成形电路和输出驱动放大器组成。芯片采用了0.35μm CMOS工艺完成了流片测试,单通道的电荷增益为65～260mV/fC,成形时间调节范围为1～4μs,测得的最好等效噪声电荷为200e。连接碲锌镉探测器后测得241 Am和57 Co全能峰的能量分辨率分别为9.6%和5.9%。初步测试结果表明:芯片的各项功能都正常,噪声的实测结果与仿真结果比较吻合,但探测器的漏电流以及输入端寄生电容使得其电子学噪声显著增加。
In order to solve the high-density and low-noise readout problem of the pixel cadmium zinc telluride detector, an 8-channel low-noise front-end readout chip is designed. Each channel consists of two stages of charge sensitive preamplifiers, a fourth order semi-Gauss forming circuit and an output drive amplifier. The chip uses 0.35μm CMOS process to complete the chip test, single-channel charge gain of 65 ~ 260mV / fC, forming time adjustment range of 1 ~ 4μs, the best measured equivalent noise charge of 200e. The energy resolution of the 241 Am and 57 Co all-around peaks measured with the CdTe detector was 9.6% and 5.9%, respectively. The preliminary test results show that all functions of the chip are normal, and the measured results of the noise are in good agreement with the simulation results. However, the leakage current of the detector and the parasitic capacitance at the input end make its electronic noise significantly increase.