38.5-300 kHz-Fundamental-Frequency Tuning Range 16.9 mW-Power Digital Denoising System for Proton Sound Detectors in 28 nm CMOS

This paper presents a digital denoising stage for Proton Sound Detectors, that measures the range (the penetration depth) of clinical proton beams, by sensing the Time-of-Flight (ToF) of the weak acoustic signal emitted at the end of the beam penetration path. Such acoustic signal/pulse is initially fed to a low-noise analog front-end for digitalization and then to the Acoustic Denoising Digital Signal Processing (AcousticDenDSP) stage. The digital acoustic pulse has a noise bandwidth of 1 MHz and a much narrower acoustic bandwidth, centered on different fundamental frequencies (38.5 kHz (300 kHz) for 200 MeV (65 MeV) clinical beams). Thus, the AcousticDenDSP system exhibits 50 kHz/350 kHz programmable center frequency (to manage different beam energy scenarios), performs a stopband noise rejection of 80 dB/decease (4
^th
-order) and minimize phase distortion providing a maximum Time-of- Flight error lower than 0.09% (of proton beam range). The system has been designed in 28 nm CMOS, occupies an area of 0.225 mm
²
and has been fully characterized at a behavioral/electrical level (after stimulation by a real proton-induced acoustic pulse). The clock frequency is 100 MHz and the power consumption estimated is 16.9 m W, with a static power contribution of 0.075 mW.