We present a radio system that could be used in millimeter-scale wireless neural implants. The system is RF-powered and demonstrates Mbps data rates required for neuromodulation and recording applications. The radio transmits at 58 Mb/s and receives at 2.5 Mb/s maximum data rates. The transceiver uses a duplexer to achieve full-duplex communication via frequency-division duplexing at 1.74 and 1.86 GHz for TX and RX, respectively. The average power consumption of the transmitter is 93 μW at 58 Mb/s, while that of the receiver is 7.2 μW at 2.5 Mb/s. The transceiver was fabricated using 40-nm LP CMOS process and occupies 0.8 mm² of die area. Including the off-chip duplexer, the system occupies 2 × 1.6 × 0.6 mm³.