Human body communications require energyefficient transceivers to connect diverse devices on the human body for wellness and medical applications. This paper presents a fully digital pulse-based transmitter (TX) for capacitive bodycoupled communications (c-BCC) in 28 nm FD-SOI CMOS. The transmitter is operating at 450 MHz where surface wave (SW) propagation is the dominant mechanism of capacitive body coupled communication (c-BCC), offering a larger bandwidth with a more stable channel. The heavily duty-cycled transmitter uses a 90 MHz free-running oscillator and edge combiners to generate OOK Gaussian-shaped pulses through a switchedcapacitor PA. Wide range forward body-biasing (FBB), specific to FD-SOI technology, allows frequency tuning and adaptive efficiency optimization as a function of data rate. The proposed transmitter consumes 17 to 76 µW for flexible data rates from 0.1 to 27 Mb/s (170 pJ/b down to 2.8 pJ/b) with up to 14 % system efficiency under 0.5 V supply voltage.