Low-Noise Wide Dynamic Range Charge Sensitive Amplifier in 65 nm CMOS Technology for the Second Flight of the GAPS Experiment

This work describes a low-noise charge sensitive amplifier designed in a commercial 65nm CMOS technology for the second flight of the General AntiParticle Spectrometer balloon experiment, aimed at the indirect search of dark matter. The circuit has been developed as part of the upgrade of the chip employed in the readout of the lithium-drifted silicon detectors of the inner tracker and features dynamic signal compression to cope with the wide input dynamic range. A novel solution using dynamic threshold MOSFETs for the non-linear feedback capacitor implementation has been investigated. The paper will discuss the amplifier architecture, with a focus on the input and feedback device design and the relevant simulation results.