Design and Performance Evaluation of Super Pixel Circuits with a Built-in LDO Regulator in a Pixel Readout ASIC for Hybrid X-ray Imaging Detectors

This paper presents a novel pixel circuit topology with a built-in pixelated low-dropout (LDO) regulator to enhance consistency in an energy-resolving photon-count pixel readout ASIC. A super pixel is organized by a 2 × 2 pixel array. A common LDO is built into the super pixel to provide a stable supply voltage for analog blocks of four pixels, ensuring the consistency of the supply voltage of each pixel unit. The maximum simulated IR drop is only 70 μV. The input charge is 1 fC ~ 10 fC. The equivalent noise charge is 200 e- (@ 200 fF). The power consumption is about 40 μW/pixel. The simulated results indicate that the proposed scheme can well enhance the consistency of the output data from each pixel readout circuit.