A 512×256 TFT-Based Flat-Panel Detector With High Sensitivity, High Frame Rate, and Wide Dynamic Range for Industrial Soft X-Ray Imaging

Active Pixel Sensors (APS) outperform Passive Pixel Sensors (PPS) in both sensitivity and frame rate, and while they have become the dominant architecture in CMOS imaging technology, their application in thin-film transistor (TFT)-based flat-panel X-ray detectors (FPDs) remains limited—primarily due to reduced fill factor, which compromises sensitivity. This work introduces a novel APS architecture tailored for soft X-ray FPDs aimed at non-destructive testing (NDT) applications. The proposed design addresses the critical demands of high sensitivity, high signal-to-noise ratio (SNR), wide dynamic range, and high frame rate, offering a promising solution for industrial imaging scenarios. Unlike conventional PPS designs, this architecture utilizes a double-gate TFT operating in the subthreshold region to simultaneously compress and amplify optical signals. This approach significantly enhances both the detection limit and sensing range, achieving a sensitivity exceeding 10² A/W and a gain over 10⁵% at a wavelength of 560 nm. The system demonstrates a wide dynamic range of 120 dB and a maximum photo-to-dark current ratio (PDCR) of 5.7×10⁵. The array features random-access capabilities, achieving a frame rate of 88 frames per second, positioning it as a strong candidate for real-time, in-line inspection applications.