High-performance low-noise 128-channel readout-integrated circuit for flat-panel x-ray detector systems

Abstract

ABSTRACT A silicon mixed-signal integrated circuit is n eeded to extract and process x-ray induc ed signals from a coated flat panel thin film transistor array (TFT) in order to generate a digital x-ray image. Indigo Systems Corporation has designed, fabricated, and tested such a readout integr ated circuit (ROIC), the ISC9717. This off-the-shelf, high performance, low-noise, 128-channel device is fully programmable with a multistage pipelined architecture and a 9 to 14-bit programmable A/D converter per channel, making it suitable for numerous X-ray medical imaging applications. These include high-resolution radiography in single frame mode and fluoroscopy where high frame rates are required. The ISC9717 can be used with various flat panel arrays and solid-state detectors materials: Selenium (Se), Cesium Iodide (CsI), Silicon (Si), Amorphous Silicon, Gallium Arseni de (GaAs), and Cadmium Zinc Telluride (CdZnTe). The 80-micron pitch ROIC is designed to interface (wire bonding or flip-chip) along one or two sides of the x-ray panel, where ROICs are abutted vertically, each reading out charge from pixels multiplexed onto 128 horizontal read lines. The paper will present the design and test results of the ROIC, including the mechanical and electrical interface to a TFT array, system performance requirements, output multiplexing of the digital signals to an off-board processor, and characterization test results from fabricated arrays. Keywords: ASIC, readout integrated circuit (ROIC), CMOS, thin film transistor (TFT), multiplexing, digital x-ray image, A/D converter, integration time, co rrelated double sampling, low-pass filter