Performance of front-end mixed-signal ASIC for onboard CCD cameras
Performance of front-end mixed-signal ASIC for onboard CCD cameras
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DOI：
10.1117/12.2055658
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发表时间：
2014-07
影响因子：
1.3
通讯作者：
H. Nakajima;S. Inoue;Ryo Nagino;N. Anabuki;K. Hayashida;H. Tsunemi;J. Doty;H. Ikeda
中科院分区：
文献类型：
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作者：
H. Nakajima;S. Inoue;Ryo Nagino;N. Anabuki;K. Hayashida;H. Tsunemi;J. Doty;H. Ikeda
报道了一种用于星载X射线CCD相机的读出专用集成电路的发展现状。快速的低噪声读出是未来高灵敏度望远镜实现免堆积成像光谱学的关键。ASTRO-H/SXI专用ASIC只有在68 kHz的低像素速率下才有足够的噪声性能。然后，我们一直在开发采用四阶ΔΣ调制器的升级专用集成电路。升级调制器的阶数使我们能够更少地对CCD信号进行过采样，从而使我们。数字化的脉冲高度是用抽取滤波器解密的连续比特流。通过仿真优化了滤波器的加权系数，使信噪比达到最大。给出了系统的输入等效噪声、增益、有效信号范围等性能指标。在高达625 kHz的第一次功能测试中，成功地获得了数字化的脉冲高度数据。IEN与ASTRO-H/SXI芯片获得的结果几乎相同。从增益函数得到的残差约为0.1%，比传统ASIC的残差提高了两倍。假设电荷耦合器件的增益与ASTRO-H的增益相同，在增益最大的情况下，有效范围为30keV。通过改变增益，它可以管理100KE-的信号电荷。这些结果将反馈给脉冲高度解密滤波器的优化。
We report on the development status of the readout ASIC for an onboard X-ray CCD camera. The quick low- noise readout is essential for the pile-up free imaging spectroscopy with the future highly sensitive telescope. The dedicated ASIC for ASTRO-H/SXI has sufficient noise performance only at the slow pixel rate of 68 kHz. Then we have been developing the upgraded ASIC with the fourth-order ΔΣ modulators. Upgrading the order of the modulator enables us to oversample the CCD signals less times so that we. The digitized pulse height is a serial bit stream that is decrypted with a decimation filter. The weighting coefficient of the filter is optimized to maximize the signal-to-noise ratio by a simulation. We present the performances such as the input equivalent noise (IEN), gain, effective signal range. The digitized pulse height data are successfully obtained in the first functional test up to 625 kHz. IEN is almost the same as that obtained with the chip for ASTRO-H/SXI. The residuals from the gain function is about 0.1%, which is better than that of the conventional ASIC by a factor of two. Assuming that the gain of the CCD is the same as that for ASTRO-H, the effective range is 30 keV in the case of the maximum gain. By changing the gain it can manage the signal charges of 100 ke-. These results will be fed back to the optimization of the pulse height decrypting filter.