The Rabi frequency of oscillation of the nuclear magnetization vector of a sample in an NMR system may be controlled by modifying only the duty cycle of RF pulses delivered to the sample, without modifying the amplitude of the RF pulses, until the energy delivered at the Larmor frequency is adjusted to a desired amount. An impedance matching network between an NMR transceiver and an NMR coil may perform both power matching and noise matching simultaneously. During a transmission mode, the impedance matching network is connected to a transmitter portion of the transceiver, and the impedance of the coil is matched to the driver resistance. During a receiver mode, the impedance matching network is disconnected from the transmitter portion so that the impedance matching network remains connected only to the receiver portion, and signal-to-noise ratio in received NMR signals is maximized.