We present a fully-integrated transceiver ASIC for multi-nuclei nuclear magnetic resonance (NMR) measurements with operating frequencies up to 770MHz. The NMR-on-a-chip transceiver co-integrates a low-IF receiver, consisting of an LNA, quadrature down-conversion mixers, and variable gain amplifiers, a PA, and a frequency synthesizer. The ASIC occupies a total chip area of 1100x900μm^2. The PA has a maximum peak-to-peak output current of 210mA. The receiver chain has a maximum conversion gain of 66dB with a minimum input-referred noise of 610pV/√Hz. The chip performance is verified in NMR applications, in which the presented system achieves a state-of-the-art normalized spin sensitivity of 8.3x10^17spins/√Hz*T^2/m.