基于电流模式的硅像素探测器前端读出ASIC设计

Design of a Front- end Readout ASIC for Silicon Pixel Detector Based on Current- mode Approach

针对应用于同步辐射的硅像素探测器,设计了一种基于电流模式的像素型前端读出单元电路,像素单元电路主要包括电荷灵敏前置放大器、跨导放大器、电流甄别器、阈值调节电路和计数器等,实现了信号放大、电压转为电流、信号甄别以及计数等功能。芯片基于SMIC 0.13μm/1.2V CMOS工艺设计,像素单元面积为100μm×100μm,仿真结果表明:像素单元静态功耗为50μW,等效噪声电荷低于100e-,不一致性小于100e-,能量甄别范围为8 ke V^20 ke V,达到了预期设计目标。与电压模式的像素单元电路相比,具有结构简单、功耗低、芯片面积小以及抗干扰能力强的特点。

A front-end readout circuit based on current-mode approach has been designed for silicon pixel detector used in synchrotron radiation detection.The pixel circuit is composed of a charge sensitive preamplifi-er, an operational trans-conductance amplifier, a current-mode discriminator, a threshold adjustment circuit and a counter.It can perform signal amplification, voltage-to-current conversion, signal discrimination and counting.The chip is designed on SMIC 0.13 μm/1.2V CMOS technology, with a pixel size of 100 μm ×100μm.Simulation results show that the static power consumption of the pixel is 50μW, with an equivalent input noise of less than 100e-rms.The threshold uniformity is also better than 100e -rms, and the energy detection range is from 8 keV to 20 keV, which fulfill the specification.Compared with the existed chip based on voltage-mode approach, the current-mode approach owns advantages of compact structure, low power, small occu-pation and good noise immunity.