Design and testing of a low impedance transceiver circuit for nitrogen-14 nuclear quadrupole resonance

作者：Sato Akaba Hideo^*

来源：Solid State Nuclear Magnetic Resonance, 2014, 63-64: 30-36.

DOI：10.1016/j.ssnmr.2014.09.002

• Nitrogen-14 nuclear quadrupole resonance
• Transmit receiver switch circuit
• Class-D amplifier
• Transimpedance amplifier
• Q switch
• Non-invasive detection
• Illicit drugs
• Explosives
• Counterfeit medicines

A low impedance transceiver circuit consisting of a transmit-receive switch circuit, a class-D amplifier and a transimpedance amplifier (TIA) was newly designed and tested for a nitrogen-14 NQR. An NQR signal at 1.37 MHz from imidazole was successfully observed with the dead time of similar to 85 mu s under the high Q transmission (Q similar to 120) and reception (Q similar to 140). The noise performance of the low impedance TEA with an NQR probe was comparable with a commercial low noise 50 Omega amplifier (voltage input noise: 0.25 nV/root Hz) which was also connected to the probe. The protection voltage for the pre-amplifier using the low impedance transceiver was similar to 10 times smaller than that for the pre-amplifier using a 50 Omega conventional transceiver, which is suitable for NQR remote sensing applications.

• 出版日期2014-11