A charge-integration pixel readout chip features IR-drop effect mitigation by distributed LDOs

摘要

HYLITE (High dYnamic range free electron Laser Imaging deTEctor) is a chargeintegration pixel detector readout chip, which is designed for SHINE (Shanghai high repetition rate XFEL and extreme light facility). The targeting pixel array of a full-size chip is 128 × 128 with a pixel pitch of 100 μm. The dynamic range of HYLITE is 1 ~ 10000 photons at 12 keV, and the frame rate is 10 kHz. Large array size, high dynamic range, and high readout speed result in a big challenge of large power consumption and a significant IR-Drop effect. We implemented HYLITE0.2, which is the second prototype chip fabricated in a CMOS 130 nm process. Compared with HYLITE0.1, HYLITE0.2 aims to implement a full-function chip with a further shrunk pixel size, while the foreseen problem of severe IR-Drop effect of the full-size chip must be solved. To mitigate the IR-Drop effect, we proposed a novel architecture of distributed in-array Low-Dropout Regulators (LDOs). The pixel array consists of 16 × 24 pixels, and the full functionality was implemented within a pixel pitch of 100 μm. Measurements show that pixels powered by the proposed architecture work well, and the gain gradient of those pixels is 31.8% of the pixels powered by the conventional architecture.