Speaker
Description
The Topmetal series CMOS pixel detectors employ metal electrodes for direct charge collection and have been widely adopted in gas pixel detectors (GPDs) for X-ray polarization measurements. The performance of these detectors, particularly in terms of dynamic range, event rate capability, and energy measurement accuracy, is critical to achieving high detection efficiency. This work presents a detailed analysis of the pixel front-end circuit architecture of Topmetal detectors and introduces a series of optimizations to enhance their performance. To validate the proposed improvements, a prototype pixel front-end ASIC was designed and fabricated using the GSMC 130 nm CMOS process. Each pixel primarily consists of a low‑noise charge sensitive amplifier (CSA), a peak-hold circuit, a comparator, and a two-stage buffer. Results demonstrate that the optimized pixel achieves an equivalent noise charge (ENC) of $22.48 e^- + 0.51 e^-/fF$, a charge-voltage conversion gain of $66.95 \mu V/e^-$, and a dynamic range of $25k e^-$ with a non-linearity of 2.93%. Compared to previous Topmetal generations, the optimized pixel exhibits an extended dynamic range, improved linearity, enhanced energy measurement accuracy, and increased event rate capability (supporting up to 10 kcps), demonstrating its potential for large-scale integration in next-generation high-performance pixel detectors for X-ray polarization measurements.
| Workshop topics | Front-end electronics and readout |
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