This paper presents a fully integrated UWB-IR transceiver front end operating in the 7.25-8.5 GHz band designed for high overall transmission and detection energy efficiency and robustness to interferers. The transceiver features a pulsed transmitter that wakes up when triggered by a digital signal, generates a pulse, and automatically switches-off in less than 2ns. The receiver includes an LNA, a VGA, a squarer, a windowed integrator, and supports OOK and PPM modulation. A prototype of the transceiver was integrated in a 130 nm CMOS technology. The transmitter delivers 13 pJ/pulse with an efficiency η = 7%, well in excess of comparable designs, and, using pulse polarity scrambling, it complies with the FCC spectral emission limits up to a PRF = 5MHz. The receiver achieves a normalized sensitivity of -87dBm, requiring 150 pJ/b up to the maximum TX PRF = 5MHz, and can tolerate interferers up to -12 dBm at 5.4 GHz.