A wide dynamic range high linearity in-pixel data acquisition front-end for computed tomography

Computed tomography (CT) detectors require wide dynamic range (DR) and high linearity. This paper reports the design of a new CMOS pixel with in-pixel acquisition front-end for CT in a 0.35 mum CMOS process. The detector uses a synchronous partial quantization scheme to linearly expand the dynamic range with a constant potential well size. A low-power analog-to-digital converter is also designed in the pixel. HSPICE simulations verify that the designed detector is able to achieve 96 dB DR, with -104 dB total-harmonic-distortion (THD) over the dynamic range. No calibration procedure is required for the high linearity. The input-referred noise is less than 1 mV_rms. The frame rate of the designed detector is 2.4 k Hz.