Speaker
Description
Gas pixel detectors (GPDs) are widely used in astronomical X-ray polarimetry for photoelectron event reconstruction. Future GPD applications impose increasing demands on front-end readout ASICs in terms of throughput and pixel-level performance. This work presents a prototype front-end readout ASIC developed for next-generation GPD systems. The chip integrates a $32 \times 30$ pixel array with a pixel pitch of $45\,\mathrm{\mu m} \times 45\,\mathrm{\mu m}$. Each pixel incorporates a charge-sensitive analog front-end, while a localized and noise-robust triggering scheme based on a $2 \times 2$ pixel block architecture enables block-level time-of-arrival (ToA) measurement and self-triggered readout. A configurable readout architecture is adopted, supporting both trigger-based region-of-interest (ROI) readout and triggerless full-frame (FF) readout. Measurement results show that the pixel front-end achieves a charge-to-voltage conversion gain of $69\,\mathrm{\mu V/e^-}$, an equivalent noise charge (ENC) of approximately $50\,\mathrm{e^-}$, and an input dynamic range of $26\,\mathrm{k\,e^-}$ with about 3% nonlinearity. The block-level ToA measurement provides a time resolution of $25\,\mathrm{ns}$, a timing precision of $16.5\,\mathrm{ns}$, and a dynamic range of $25.6\,\mathrm{\mu s}$.
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