A robust CMOS Receiver front-end for Nuclear Quadrupole Resonance based explosives detection

Hidden bombs and abandoned military landmines buried in the afterwar field has become a severe threat to the society. A stand-off, high sensitive and portable explosive detection system is required to help this situation. Nuclear Quadrupole Resonance (NQR) detection technology has proven to be a highly effective solution for unambiguously detecting explosives, since NQR is an inherent characteristic of explosive substances. However, the current NQR based explosive detectors for field application have bulky size, and are vulnerable to the noise and Radio Frequency Interference (RFI). To address this problem, a robust CMOS Receiver front-end for NQR signal detection is proposed in this work. A Continuous Time Least Mean Square (CTLMS) adaptive filter is employed to mitigate RFI in the analog domain before the data quantization and further processing. With the proposed receiver circuit, the requirement of high precision data acquisition and complex detection algorithms downstream with high computation cost can be effectively relaxed. The proposed circuit system is implemented with 0.18 µm RF CMOS process.