A fully-integrated, 3-5 GHz Impulse-Radio UWB transceiver with on-chip flash ADC is designed in 90 nm-CMOS. A new scheme for receiver phase acquisition is proposed that uses pulse injection-locking to synchronize the receive clock with the transmitted data, eliminating the need for clock/data recovery (CDR), requiring only static receiver phase alignment with the transmitted pulses at startup. Transmitter pre-emphasis equalization is utilized to mitigate the effect of multipath on bit-error rate (BER). Occupying 2 mm2 die area, the transceiver achieves a data rate of 500 Mbps, energy efficiency of 0.18 nj/b at 500 Mbps, and a RX raw BER of <; 10-3 across a distance of 10 cm at 125 Mbps. In a real multipath environment, BER improves by 2.35× after equalization of the first multipath reflection.