HEXID2: A Low-Power, Low-Noise Pixel Readout ASIC for Hyperspectral Energy-Resolving X-Ray Imaging Detectors

We present a low-power, low-noise prototype pixel readout application specific integrated circuit (ASIC) for hyperspectral energy-resolving X-ray imaging detectors. The ASIC provides 16-by-16 channels to read out positive and negative charges from 16-by-16 hexagonal silicon or CZT detector arrays, at a pitch size of 250 gm, to achieve good spatial resolution and the ability to record the energy of a detected photon as well as its position. The readout is done by bump bonding the anodes to the inputs of the ASIC. Each channel of the ASIC provides low-noise charge amplification, high-order shaping with baseline stabilization, discrimination, extraction of amplitude (with neighbour channels), multiplexing, and dissipates similar to 0.6 mW. A smart readout of the triggered pixel and its adjacent six pixels in the hexagonal configuration allows reconstruction of events with charge sharing correction, and can be used to estimate the depth of the photon interaction and to suppress background events. The target equivalent noise charge (ENC) is-40 electrons for silicon detector pixel and similar to 15 electrons for CZT detector pixel.