Minimizing intrinsic input leakage current and capacitance in hybrid sensor readout circuits

Noise in many sensor systems and particularly in radiation detection systems is determined by the input capacitance and leakage current. In hybrid detection systems a protection against electrostatic discharge, ideally transparent, adds parasitics at the input pad. Sensors representing small equivalent capacitance seen from the input or small leakage (or both) are sensitive to such additional parasitics of the readout electronics. This work focuses on reducing these parasitics. Focusing on hybrid sensor for ionizing radiation detection, the radiation tolerance has also been considered. Input protection pads targeting minimized increase in leakage current due to Total Ionizing Dose (TID) have been implemented in REDComET (Radiation and Electrostatic Discharge Combined Effects Test Chip) fabricated in 180 nm CMOS. In addition the testchip studies techniques for the input leakage current compensation: leakage current originating from the detector as well as from the pad protection.